28 lines
880 B
Plaintext
28 lines
880 B
Plaintext
|
drop table if exists t1;
|
||
|
|
select {fn length("hello")}, { date "1997-10-20" };
|
||
|
|
{fn length("hello")} 1997-10-20
|
||
|
|
5 1997-10-20
|
||
|
|
create table t1 (a int not null auto_increment,b int not null,primary key (a,b));
|
||
|
|
insert into t1 SET A=NULL,B=1;
|
||
|
|
insert into t1 SET a=null,b=2;
|
||
|
|
select * from t1 where a is null and b=2;
|
||
|
|
a b
|
||
|
|
2 2
|
||
|
|
select * from t1 where a is null;
|
||
|
|
a b
|
||
|
|
explain select * from t1 where b is null;
|
||
|
|
id select_type table type possible_keys key key_len ref rows Extra
|
||
|
|
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE
|
||
|
|
drop table t1;
|
||
|
|
CREATE TABLE t1 (a INT AUTO_INCREMENT PRIMARY KEY);
|
||
|
|
INSERT INTO t1 VALUES (NULL);
|
||
|
|
SELECT sql_no_cache a, last_insert_id() FROM t1 WHERE a IS NULL;
|
||
|
|
a last_insert_id()
|
||
|
|
1 1
|
||
|
|
SELECT sql_no_cache a, last_insert_id() FROM t1 WHERE a IS NULL;
|
||
|
|
a last_insert_id()
|
||
|
|
SELECT sql_no_cache a, last_insert_id() FROM t1;
|
||
|
|
a last_insert_id()
|
||
|
|
1 1
|
||
|
|
DROP TABLE t1;
|