741 lines
19 KiB
Plaintext
741 lines
19 KiB
Plaintext
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drop table if exists t1,t2,t3;
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create table t1 (a int not null,b int not null, primary key (a)) engine=heap comment="testing heaps" avg_row_length=100 min_rows=1 max_rows=100;
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insert into t1 values(1,1),(2,2),(3,3),(4,4);
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delete from t1 where a=1 or a=0;
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show keys from t1;
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Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment
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t1 0 PRIMARY 1 a NULL 3 NULL NULL HASH
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select * from t1;
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a b
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2 2
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3 3
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4 4
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select * from t1 where a=4;
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a b
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4 4
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update t1 set b=5 where a=4;
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update t1 set b=b+1 where a>=3;
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replace t1 values (3,3);
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select * from t1;
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a b
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2 2
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3 3
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4 6
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alter table t1 add c int not null, add key (c,a);
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drop table t1;
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create table t1 (a int not null,b int not null, primary key (a)) engine=memory comment="testing heaps";
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insert into t1 values(1,1),(2,2),(3,3),(4,4);
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delete from t1 where a > 0;
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select * from t1;
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a b
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drop table t1;
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create table t1 (a int not null,b int not null, primary key (a)) engine=heap comment="testing heaps";
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insert into t1 values(1,1),(2,2),(3,3),(4,4);
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alter table t1 modify a int not null auto_increment, engine=myisam, comment="new myisam table";
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select * from t1;
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a b
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1 1
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2 2
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3 3
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4 4
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drop table t1;
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create table t1 (a int not null) engine=heap;
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insert into t1 values (869751),(736494),(226312),(802616),(728912);
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select * from t1 where a > 736494;
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a
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869751
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802616
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alter table t1 add unique uniq_id(a);
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select * from t1 where a > 736494;
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a
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869751
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802616
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select * from t1 where a = 736494;
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a
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736494
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select * from t1 where a=869751 or a=736494;
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a
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736494
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869751
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select * from t1 where a in (869751,736494,226312,802616);
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a
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226312
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736494
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802616
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869751
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alter table t1 engine=myisam;
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explain select * from t1 where a in (869751,736494,226312,802616);
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 range uniq_id uniq_id 4 NULL 4 Using where; Using index
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drop table t1;
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create table t1 (x int not null, y int not null, key x (x), unique y (y))
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engine=heap;
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insert into t1 values (1,1),(2,2),(1,3),(2,4),(2,5),(2,6);
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select * from t1 where x=1;
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x y
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1 3
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1 1
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select * from t1,t1 as t2 where t1.x=t2.y;
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x y x y
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1 1 1 1
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2 2 2 2
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1 3 1 1
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2 4 2 2
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2 5 2 2
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2 6 2 2
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explain select * from t1,t1 as t2 where t1.x=t2.y;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL x NULL NULL NULL 6
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1 SIMPLE t2 eq_ref y y 4 test.t1.x 1
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drop table t1;
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create table t1 (a int) engine=heap;
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insert into t1 values(1);
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select max(a) from t1;
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max(a)
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1
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drop table t1;
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CREATE TABLE t1 ( a int not null default 0, b int not null default 0, key(a), key(b) ) ENGINE=HEAP;
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insert into t1 values(1,1),(1,2),(2,3),(1,3),(1,4),(1,5),(1,6);
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select * from t1 where a=1;
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a b
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1 6
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1 5
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1 4
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1 3
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1 2
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1 1
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insert into t1 values(1,1),(1,2),(2,3),(1,3),(1,4),(1,5),(1,6);
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select * from t1 where a=1;
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a b
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1 6
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1 5
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1 4
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1 3
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1 2
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1 1
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1 6
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1 5
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1 4
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1 3
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1 2
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1 1
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drop table t1;
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create table t1 (id int unsigned not null, primary key (id)) engine=HEAP;
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insert into t1 values(1);
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select max(id) from t1;
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max(id)
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1
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insert into t1 values(2);
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select max(id) from t1;
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max(id)
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2
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replace into t1 values(1);
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drop table t1;
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create table t1 (n int) engine=heap;
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drop table t1;
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create table t1 (n int) engine=heap;
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drop table if exists t1;
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CREATE table t1(f1 int not null,f2 char(20) not
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null,index(f2)) engine=heap;
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INSERT into t1 set f1=12,f2="bill";
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INSERT into t1 set f1=13,f2="bill";
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INSERT into t1 set f1=14,f2="bill";
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INSERT into t1 set f1=15,f2="bill";
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INSERT into t1 set f1=16,f2="ted";
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INSERT into t1 set f1=12,f2="ted";
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INSERT into t1 set f1=12,f2="ted";
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INSERT into t1 set f1=12,f2="ted";
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INSERT into t1 set f1=12,f2="ted";
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delete from t1 where f2="bill";
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select * from t1;
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f1 f2
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16 ted
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12 ted
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12 ted
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12 ted
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12 ted
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drop table t1;
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create table t1 (btn char(10) not null, key(btn)) engine=heap;
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insert into t1 values ("hello"),("hello"),("hello"),("hello"),("hello"),("a"),("b"),("c"),("d"),("e"),("f"),("g"),("h"),("i");
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explain select * from t1 where btn like "q%";
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL btn NULL NULL NULL 14 Using where
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select * from t1 where btn like "q%";
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btn
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alter table t1 add column new_col char(1) not null, add key (btn,new_col), drop key btn;
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update t1 set new_col=left(btn,1);
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explain select * from t1 where btn="a";
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL btn NULL NULL NULL 14 Using where
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explain select * from t1 where btn="a" and new_col="a";
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ref btn btn 11 const,const 2 Using where
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drop table t1;
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CREATE TABLE t1 (
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a int default NULL,
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b int default NULL,
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KEY a (a),
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UNIQUE b (b)
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) engine=heap;
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INSERT INTO t1 VALUES (NULL,99),(99,NULL),(1,1),(2,2),(1,3);
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SELECT * FROM t1 WHERE a=NULL;
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a b
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explain SELECT * FROM t1 WHERE a IS NULL;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ref a a 5 const 2 Using where
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SELECT * FROM t1 WHERE a<=>NULL;
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a b
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NULL 99
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SELECT * FROM t1 WHERE b=NULL;
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a b
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explain SELECT * FROM t1 WHERE b IS NULL;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ref b b 5 const 1 Using where
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SELECT * FROM t1 WHERE b<=>NULL;
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a b
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99 NULL
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INSERT INTO t1 VALUES (1,3);
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ERROR 23000: Duplicate entry '3' for key 'b'
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DROP TABLE t1;
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CREATE TABLE t1 (
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a int default NULL,
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key a (a)
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) ENGINE=HEAP;
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INSERT INTO t1 VALUES (10), (10), (10);
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EXPLAIN SELECT * FROM t1 WHERE a=10;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ref a a 5 const 3 Using where
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SELECT * FROM t1 WHERE a=10;
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a
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10
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10
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10
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DROP TABLE t1;
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CREATE TABLE t1 (a int not null, primary key(a)) engine=heap;
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INSERT into t1 values (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11);
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DELETE from t1 where a < 100;
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SELECT * from t1;
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a
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DROP TABLE t1;
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CREATE TABLE `job_titles` (
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`job_title_id` int(6) unsigned NOT NULL default '0',
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`job_title` char(18) NOT NULL default '',
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PRIMARY KEY (`job_title_id`),
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UNIQUE KEY `job_title_id` (`job_title_id`,`job_title`)
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) ENGINE=HEAP;
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SELECT MAX(job_title_id) FROM job_titles;
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MAX(job_title_id)
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NULL
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DROP TABLE job_titles;
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CREATE TABLE t1 (a INT NOT NULL, B INT, KEY(B)) ENGINE=HEAP;
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INSERT INTO t1 VALUES(1,1), (1,NULL);
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SELECT * FROM t1 WHERE B is not null;
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a B
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1 1
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DROP TABLE t1;
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CREATE TABLE t1 (pseudo char(35) PRIMARY KEY, date int(10) unsigned NOT NULL) ENGINE=HEAP;
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INSERT INTO t1 VALUES ('massecot',1101106491),('altec',1101106492),('stitch+',1101106304),('Seb Corgan',1101106305),('beerfilou',1101106263),('flaker',1101106529),('joce8',5),('M4vrick',1101106418),('gabay008',1101106525),('Vamp irX',1101106291),('ZoomZip',1101106546),('rip666',1101106502),('CBP ',1101106397),('guezpard',1101106496);
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DELETE FROM t1 WHERE date<1101106546;
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SELECT * FROM t1;
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pseudo date
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ZoomZip 1101106546
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DROP TABLE t1;
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create table t1(a char(2)) engine=memory;
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insert into t1 values (NULL), (NULL);
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delete from t1 where a is null;
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insert into t1 values ('2'), ('3');
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select * from t1;
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a
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3
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2
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drop table t1;
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set storage_engine=HEAP;
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create table t1 (v varchar(10), c char(10), t varchar(50));
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insert into t1 values('+ ', '+ ', '+ ');
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set @a=repeat(' ',20);
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insert into t1 values (concat('+',@a),concat('+',@a),concat('+',@a));
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Warnings:
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Note 1265 Data truncated for column 'v' at row 1
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select concat('*',v,'*',c,'*',t,'*') from t1;
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concat('*',v,'*',c,'*',t,'*')
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*+ *+*+ *
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*+ *+*+ *
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show create table t1;
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Table Create Table
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t1 CREATE TABLE `t1` (
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`v` varchar(10) DEFAULT NULL,
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`c` char(10) DEFAULT NULL,
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`t` varchar(50) DEFAULT NULL
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) ENGINE=MEMORY DEFAULT CHARSET=latin1
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create table t2 like t1;
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show create table t2;
|
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Table Create Table
|
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t2 CREATE TABLE `t2` (
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`v` varchar(10) DEFAULT NULL,
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`c` char(10) DEFAULT NULL,
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`t` varchar(50) DEFAULT NULL
|
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) ENGINE=MEMORY DEFAULT CHARSET=latin1
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create table t3 select * from t1;
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show create table t3;
|
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Table Create Table
|
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t3 CREATE TABLE `t3` (
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`v` varchar(10) DEFAULT NULL,
|
|||
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`c` char(10) DEFAULT NULL,
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`t` varchar(50) DEFAULT NULL
|
|||
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) ENGINE=MEMORY DEFAULT CHARSET=latin1
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alter table t1 modify c varchar(10);
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show create table t1;
|
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|
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Table Create Table
|
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|
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t1 CREATE TABLE `t1` (
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|
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`v` varchar(10) DEFAULT NULL,
|
|||
|
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`c` varchar(10) DEFAULT NULL,
|
|||
|
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`t` varchar(50) DEFAULT NULL
|
|||
|
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) ENGINE=MEMORY DEFAULT CHARSET=latin1
|
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alter table t1 modify v char(10);
|
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show create table t1;
|
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Table Create Table
|
|||
|
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t1 CREATE TABLE `t1` (
|
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|
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`v` char(10) DEFAULT NULL,
|
|||
|
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`c` varchar(10) DEFAULT NULL,
|
|||
|
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`t` varchar(50) DEFAULT NULL
|
|||
|
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) ENGINE=MEMORY DEFAULT CHARSET=latin1
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alter table t1 modify t varchar(10);
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Warnings:
|
|||
|
|
Warning 1265 Data truncated for column 't' at row 2
|
|||
|
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show create table t1;
|
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|
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Table Create Table
|
|||
|
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t1 CREATE TABLE `t1` (
|
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`v` char(10) DEFAULT NULL,
|
|||
|
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`c` varchar(10) DEFAULT NULL,
|
|||
|
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`t` varchar(10) DEFAULT NULL
|
|||
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) ENGINE=MEMORY DEFAULT CHARSET=latin1
|
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select concat('*',v,'*',c,'*',t,'*') from t1;
|
|||
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concat('*',v,'*',c,'*',t,'*')
|
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*+*+*+ *
|
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*+*+*+ *
|
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|
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drop table t1,t2,t3;
|
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create table t1 (v varchar(10), c char(10), t varchar(50), key(v), key(c), key(t(10)));
|
|||
|
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show create table t1;
|
|||
|
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Table Create Table
|
|||
|
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t1 CREATE TABLE `t1` (
|
|||
|
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`v` varchar(10) DEFAULT NULL,
|
|||
|
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`c` char(10) DEFAULT NULL,
|
|||
|
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`t` varchar(50) DEFAULT NULL,
|
|||
|
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KEY `v` (`v`),
|
|||
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KEY `c` (`c`),
|
|||
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KEY `t` (`t`(10))
|
|||
|
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) ENGINE=MEMORY DEFAULT CHARSET=latin1
|
|||
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select count(*) from t1;
|
|||
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count(*)
|
|||
|
|
270
|
|||
|
|
insert into t1 values(concat('a',char(1)),concat('a',char(1)),concat('a',char(1)));
|
|||
|
|
select count(*) from t1 where v='a';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where c='a';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where t='a';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where v='a ';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where c='a ';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where t='a ';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where v between 'a' and 'a ';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where v between 'a' and 'a ' and v between 'a ' and 'b\n';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where v like 'a%';
|
|||
|
|
count(*)
|
|||
|
|
11
|
|||
|
|
select count(*) from t1 where c like 'a%';
|
|||
|
|
count(*)
|
|||
|
|
11
|
|||
|
|
select count(*) from t1 where t like 'a%';
|
|||
|
|
count(*)
|
|||
|
|
11
|
|||
|
|
select count(*) from t1 where v like 'a %';
|
|||
|
|
count(*)
|
|||
|
|
9
|
|||
|
|
explain select count(*) from t1 where v='a ';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref v v 13 const 10 Using where
|
|||
|
|
explain select count(*) from t1 where c='a ';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref c c 11 const 10 Using where
|
|||
|
|
explain select count(*) from t1 where t='a ';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref t t 13 const 10 Using where
|
|||
|
|
explain select count(*) from t1 where v like 'a%';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ALL v NULL NULL NULL 271 Using where
|
|||
|
|
explain select count(*) from t1 where v between 'a' and 'a ';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref v v 13 const 10 Using where
|
|||
|
|
explain select count(*) from t1 where v between 'a' and 'a ' and v between 'a ' and 'b\n';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref v v 13 const 10 Using where
|
|||
|
|
alter table t1 add unique(v);
|
|||
|
|
ERROR 23000: Duplicate entry '{ ' for key 'v_2'
|
|||
|
|
select concat('*',v,'*',c,'*',t,'*') as qq from t1 where v='a' order by length(concat('*',v,'*',c,'*',t,'*'));
|
|||
|
|
qq
|
|||
|
|
*a*a*a*
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
explain select * from t1 where v='a';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref v v 13 const 10 Using where
|
|||
|
|
select v,count(*) from t1 group by v limit 10;
|
|||
|
|
v count(*)
|
|||
|
|
a 1
|
|||
|
|
a 10
|
|||
|
|
b 10
|
|||
|
|
c 10
|
|||
|
|
d 10
|
|||
|
|
e 10
|
|||
|
|
f 10
|
|||
|
|
g 10
|
|||
|
|
h 10
|
|||
|
|
i 10
|
|||
|
|
select v,count(t) from t1 group by v limit 10;
|
|||
|
|
v count(t)
|
|||
|
|
a 1
|
|||
|
|
a 10
|
|||
|
|
b 10
|
|||
|
|
c 10
|
|||
|
|
d 10
|
|||
|
|
e 10
|
|||
|
|
f 10
|
|||
|
|
g 10
|
|||
|
|
h 10
|
|||
|
|
i 10
|
|||
|
|
select v,count(c) from t1 group by v limit 10;
|
|||
|
|
v count(c)
|
|||
|
|
a 1
|
|||
|
|
a 10
|
|||
|
|
b 10
|
|||
|
|
c 10
|
|||
|
|
d 10
|
|||
|
|
e 10
|
|||
|
|
f 10
|
|||
|
|
g 10
|
|||
|
|
h 10
|
|||
|
|
i 10
|
|||
|
|
select sql_big_result trim(v),count(t) from t1 group by v limit 10;
|
|||
|
|
trim(v) count(t)
|
|||
|
|
a 1
|
|||
|
|
a 10
|
|||
|
|
b 10
|
|||
|
|
c 10
|
|||
|
|
d 10
|
|||
|
|
e 10
|
|||
|
|
f 10
|
|||
|
|
g 10
|
|||
|
|
h 10
|
|||
|
|
i 10
|
|||
|
|
select sql_big_result trim(v),count(c) from t1 group by v limit 10;
|
|||
|
|
trim(v) count(c)
|
|||
|
|
a 1
|
|||
|
|
a 10
|
|||
|
|
b 10
|
|||
|
|
c 10
|
|||
|
|
d 10
|
|||
|
|
e 10
|
|||
|
|
f 10
|
|||
|
|
g 10
|
|||
|
|
h 10
|
|||
|
|
i 10
|
|||
|
|
select c,count(*) from t1 group by c limit 10;
|
|||
|
|
c count(*)
|
|||
|
|
a 1
|
|||
|
|
a 10
|
|||
|
|
b 10
|
|||
|
|
c 10
|
|||
|
|
d 10
|
|||
|
|
e 10
|
|||
|
|
f 10
|
|||
|
|
g 10
|
|||
|
|
h 10
|
|||
|
|
i 10
|
|||
|
|
select c,count(t) from t1 group by c limit 10;
|
|||
|
|
c count(t)
|
|||
|
|
a 1
|
|||
|
|
a 10
|
|||
|
|
b 10
|
|||
|
|
c 10
|
|||
|
|
d 10
|
|||
|
|
e 10
|
|||
|
|
f 10
|
|||
|
|
g 10
|
|||
|
|
h 10
|
|||
|
|
i 10
|
|||
|
|
select sql_big_result c,count(t) from t1 group by c limit 10;
|
|||
|
|
c count(t)
|
|||
|
|
a 1
|
|||
|
|
a 10
|
|||
|
|
b 10
|
|||
|
|
c 10
|
|||
|
|
d 10
|
|||
|
|
e 10
|
|||
|
|
f 10
|
|||
|
|
g 10
|
|||
|
|
h 10
|
|||
|
|
i 10
|
|||
|
|
select t,count(*) from t1 group by t limit 10;
|
|||
|
|
t count(*)
|
|||
|
|
a 1
|
|||
|
|
a 10
|
|||
|
|
b 10
|
|||
|
|
c 10
|
|||
|
|
d 10
|
|||
|
|
e 10
|
|||
|
|
f 10
|
|||
|
|
g 10
|
|||
|
|
h 10
|
|||
|
|
i 10
|
|||
|
|
select t,count(t) from t1 group by t limit 10;
|
|||
|
|
t count(t)
|
|||
|
|
a 1
|
|||
|
|
a 10
|
|||
|
|
b 10
|
|||
|
|
c 10
|
|||
|
|
d 10
|
|||
|
|
e 10
|
|||
|
|
f 10
|
|||
|
|
g 10
|
|||
|
|
h 10
|
|||
|
|
i 10
|
|||
|
|
select sql_big_result trim(t),count(t) from t1 group by t limit 10;
|
|||
|
|
trim(t) count(t)
|
|||
|
|
a 1
|
|||
|
|
a 10
|
|||
|
|
b 10
|
|||
|
|
c 10
|
|||
|
|
d 10
|
|||
|
|
e 10
|
|||
|
|
f 10
|
|||
|
|
g 10
|
|||
|
|
h 10
|
|||
|
|
i 10
|
|||
|
|
drop table t1;
|
|||
|
|
create table t1 (a char(10), unique (a));
|
|||
|
|
insert into t1 values ('a');
|
|||
|
|
insert into t1 values ('a ');
|
|||
|
|
ERROR 23000: Duplicate entry 'a' for key 'a'
|
|||
|
|
alter table t1 modify a varchar(10);
|
|||
|
|
insert into t1 values ('a '),('a '),('a '),('a ');
|
|||
|
|
ERROR 23000: Duplicate entry 'a ' for key 'a'
|
|||
|
|
insert into t1 values ('a ');
|
|||
|
|
ERROR 23000: Duplicate entry 'a ' for key 'a'
|
|||
|
|
insert into t1 values ('a ');
|
|||
|
|
ERROR 23000: Duplicate entry 'a ' for key 'a'
|
|||
|
|
insert into t1 values ('a ');
|
|||
|
|
ERROR 23000: Duplicate entry 'a ' for key 'a'
|
|||
|
|
update t1 set a='a ' where a like 'a ';
|
|||
|
|
update t1 set a='a ' where a like 'a ';
|
|||
|
|
drop table t1;
|
|||
|
|
create table t1 (v varchar(10), c char(10), t varchar(50), key using btree (v), key using btree (c), key using btree (t(10)));
|
|||
|
|
show create table t1;
|
|||
|
|
Table Create Table
|
|||
|
|
t1 CREATE TABLE `t1` (
|
|||
|
|
`v` varchar(10) DEFAULT NULL,
|
|||
|
|
`c` char(10) DEFAULT NULL,
|
|||
|
|
`t` varchar(50) DEFAULT NULL,
|
|||
|
|
KEY `v` (`v`) USING BTREE,
|
|||
|
|
KEY `c` (`c`) USING BTREE,
|
|||
|
|
KEY `t` (`t`(10)) USING BTREE
|
|||
|
|
) ENGINE=MEMORY DEFAULT CHARSET=latin1
|
|||
|
|
select count(*) from t1;
|
|||
|
|
count(*)
|
|||
|
|
270
|
|||
|
|
insert into t1 values(concat('a',char(1)),concat('a',char(1)),concat('a',char(1)));
|
|||
|
|
select count(*) from t1 where v='a';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where c='a';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where t='a';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where v='a ';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where c='a ';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where t='a ';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where v between 'a' and 'a ';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
select count(*) from t1 where v between 'a' and 'a ' and v between 'a ' and 'b\n';
|
|||
|
|
count(*)
|
|||
|
|
10
|
|||
|
|
explain select count(*) from t1 where v='a ';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref v v 13 const # Using where
|
|||
|
|
explain select count(*) from t1 where c='a ';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref c c 11 const # Using where
|
|||
|
|
explain select count(*) from t1 where t='a ';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref t t 13 const # Using where
|
|||
|
|
explain select count(*) from t1 where v like 'a%';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 range v v 13 NULL # Using where
|
|||
|
|
explain select count(*) from t1 where v between 'a' and 'a ';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref v v 13 const # Using where
|
|||
|
|
explain select count(*) from t1 where v between 'a' and 'a ' and v between 'a ' and 'b\n';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref v v 13 const # Using where
|
|||
|
|
alter table t1 add unique(v);
|
|||
|
|
ERROR 23000: Duplicate entry '{ ' for key 'v_2'
|
|||
|
|
select concat('*',v,'*',c,'*',t,'*') as qq from t1 where v='a' order by length(concat('*',v,'*',c,'*',t,'*'));
|
|||
|
|
qq
|
|||
|
|
*a*a*a*
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
*a *a*a *
|
|||
|
|
explain select * from t1 where v='a';
|
|||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
|||
|
|
1 SIMPLE t1 ref v v 13 const # Using where
|
|||
|
|
drop table t1;
|
|||
|
|
create table t1 (a char(10), unique using btree (a)) engine=heap;
|
|||
|
|
insert into t1 values ('a');
|
|||
|
|
insert into t1 values ('a ');
|
|||
|
|
ERROR 23000: Duplicate entry 'a' for key 'a'
|
|||
|
|
alter table t1 modify a varchar(10);
|
|||
|
|
insert into t1 values ('a '),('a '),('a '),('a ');
|
|||
|
|
ERROR 23000: Duplicate entry 'a ' for key 'a'
|
|||
|
|
insert into t1 values ('a ');
|
|||
|
|
ERROR 23000: Duplicate entry 'a ' for key 'a'
|
|||
|
|
insert into t1 values ('a ');
|
|||
|
|
ERROR 23000: Duplicate entry 'a ' for key 'a'
|
|||
|
|
insert into t1 values ('a ');
|
|||
|
|
ERROR 23000: Duplicate entry 'a ' for key 'a'
|
|||
|
|
update t1 set a='a ' where a like 'a ';
|
|||
|
|
update t1 set a='a ' where a like 'a ';
|
|||
|
|
drop table t1;
|
|||
|
|
create table t1 (v varchar(10), c char(10), t varchar(50), key(v(5)), key(c(5)), key(t(5)));
|
|||
|
|
show create table t1;
|
|||
|
|
Table Create Table
|
|||
|
|
t1 CREATE TABLE `t1` (
|
|||
|
|
`v` varchar(10) DEFAULT NULL,
|
|||
|
|
`c` char(10) DEFAULT NULL,
|
|||
|
|
`t` varchar(50) DEFAULT NULL,
|
|||
|
|
KEY `v` (`v`(5)),
|
|||
|
|
KEY `c` (`c`(5)),
|
|||
|
|
KEY `t` (`t`(5))
|
|||
|
|
) ENGINE=MEMORY DEFAULT CHARSET=latin1
|
|||
|
|
drop table t1;
|
|||
|
|
create table t1 (v varchar(65530), key(v(10)));
|
|||
|
|
show create table t1;
|
|||
|
|
Table Create Table
|
|||
|
|
t1 CREATE TABLE `t1` (
|
|||
|
|
`v` varchar(65530) DEFAULT NULL,
|
|||
|
|
KEY `v` (`v`(10))
|
|||
|
|
) ENGINE=MEMORY DEFAULT CHARSET=latin1
|
|||
|
|
insert into t1 values(repeat('a',65530));
|
|||
|
|
select length(v) from t1 where v=repeat('a',65530);
|
|||
|
|
length(v)
|
|||
|
|
65530
|
|||
|
|
drop table t1;
|
|||
|
|
set storage_engine=MyISAM;
|
|||
|
|
create table t1 (a bigint unsigned auto_increment primary key, b int,
|
|||
|
|
key (b, a)) engine=heap;
|
|||
|
|
insert t1 (b) values (1),(1),(1),(1),(1),(1),(1),(1);
|
|||
|
|
select * from t1;
|
|||
|
|
a b
|
|||
|
|
1 1
|
|||
|
|
2 1
|
|||
|
|
3 1
|
|||
|
|
4 1
|
|||
|
|
5 1
|
|||
|
|
6 1
|
|||
|
|
7 1
|
|||
|
|
8 1
|
|||
|
|
drop table t1;
|
|||
|
|
create table t1 (a int not null, b int not null auto_increment,
|
|||
|
|
primary key(a, b), key(b)) engine=heap;
|
|||
|
|
insert t1 (a) values (1),(1),(1),(1),(1),(1),(1),(1);
|
|||
|
|
select * from t1;
|
|||
|
|
a b
|
|||
|
|
1 1
|
|||
|
|
1 2
|
|||
|
|
1 3
|
|||
|
|
1 4
|
|||
|
|
1 5
|
|||
|
|
1 6
|
|||
|
|
1 7
|
|||
|
|
1 8
|
|||
|
|
drop table t1;
|
|||
|
|
create table t1 (a int not null, b int not null auto_increment,
|
|||
|
|
primary key(a, b)) engine=heap;
|
|||
|
|
ERROR 42000: Incorrect table definition; there can be only one auto column and it must be defined as a key
|
|||
|
|
create table t1 (c char(255), primary key(c(90)));
|
|||
|
|
insert into t1 values ("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz");
|
|||
|
|
insert into t1 values ("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz");
|
|||
|
|
ERROR 23000: Duplicate entry 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijkl' for key 'PRIMARY'
|
|||
|
|
drop table t1;
|
|||
|
|
CREATE TABLE t1 (a int, key(a)) engine=heap;
|
|||
|
|
insert into t1 values (0);
|
|||
|
|
delete from t1;
|
|||
|
|
select * from t1;
|
|||
|
|
a
|
|||
|
|
insert into t1 values (0), (1);
|
|||
|
|
select * from t1 where a = 0;
|
|||
|
|
a
|
|||
|
|
0
|
|||
|
|
drop table t1;
|
|||
|
|
create table t1 (c char(10)) engine=memory;
|
|||
|
|
create table t2 (c varchar(10)) engine=memory;
|
|||
|
|
show table status like 't_';
|
|||
|
|
Name Engine Version Row_format Rows Avg_row_length Data_length Max_data_length Index_length Data_free Auto_increment Create_time Update_time Check_time Collation Checksum Create_options Comment
|
|||
|
|
t1 MEMORY 10 Fixed 0 11 0 # 0 0 NULL # NULL NULL latin1_swedish_ci NULL
|
|||
|
|
t2 MEMORY 10 Fixed 0 12 0 # 0 0 NULL # NULL NULL latin1_swedish_ci NULL
|
|||
|
|
drop table t1, t2;
|
|||
|
|
CREATE TABLE t1(a VARCHAR(1), b VARCHAR(2), c VARCHAR(256),
|
|||
|
|
KEY(a), KEY(b), KEY(c)) ENGINE=MEMORY;
|
|||
|
|
INSERT INTO t1 VALUES('a','aa',REPEAT('a', 256)),('a','aa',REPEAT('a',256));
|
|||
|
|
SELECT COUNT(*) FROM t1 WHERE a='a';
|
|||
|
|
COUNT(*)
|
|||
|
|
2
|
|||
|
|
SELECT COUNT(*) FROM t1 WHERE b='aa';
|
|||
|
|
COUNT(*)
|
|||
|
|
2
|
|||
|
|
SELECT COUNT(*) FROM t1 WHERE c=REPEAT('a',256);
|
|||
|
|
COUNT(*)
|
|||
|
|
2
|
|||
|
|
DROP TABLE t1;
|
|||
|
|
CREATE TABLE t1(c1 VARCHAR(100), c2 INT) ENGINE=MEMORY;
|
|||
|
|
INSERT INTO t1 VALUES('', 0);
|
|||
|
|
ALTER TABLE t1 MODIFY c1 VARCHAR(101);
|
|||
|
|
SELECT c2 FROM t1;
|
|||
|
|
c2
|
|||
|
|
0
|
|||
|
|
DROP TABLE t1;
|