mirror of
https://github.com/MariaDB/server.git
synced 2025-11-03 14:33:32 +03:00
47 lines
1.5 KiB
Plaintext
47 lines
1.5 KiB
Plaintext
drop table if exists t1;
|
|
create table t1 (id int not null, str char(10), unique(str));
|
|
explain select * from t1;
|
|
table type possible_keys key key_len ref rows Extra
|
|
t1 system NULL NULL NULL NULL 0 const row not found
|
|
insert into t1 values (1, null),(2, null),(3, "foo"),(4, "bar");
|
|
select * from t1 where str is null;
|
|
id str
|
|
1 NULL
|
|
2 NULL
|
|
select * from t1 where str="foo";
|
|
id str
|
|
3 foo
|
|
explain select * from t1 where str is null;
|
|
table type possible_keys key key_len ref rows Extra
|
|
t1 ref str str 11 const 1 Using where
|
|
explain select * from t1 where str="foo";
|
|
table type possible_keys key key_len ref rows Extra
|
|
t1 const str str 11 const 1
|
|
explain select * from t1 ignore key (str) where str="foo";
|
|
table type possible_keys key key_len ref rows Extra
|
|
t1 ALL NULL NULL NULL NULL 4 Using where
|
|
explain select * from t1 use key (str,str) where str="foo";
|
|
table type possible_keys key key_len ref rows Extra
|
|
t1 const str str 11 const 1
|
|
explain select * from t1 use key (str,str,foo) where str="foo";
|
|
Key column 'foo' doesn't exist in table
|
|
explain select * from t1 ignore key (str,str,foo) where str="foo";
|
|
Key column 'foo' doesn't exist in table
|
|
drop table t1;
|
|
explain select 1;
|
|
Comment
|
|
No tables used
|
|
create table t1 (a int not null);
|
|
explain select count(*) from t1;
|
|
Comment
|
|
Select tables optimized away
|
|
insert into t1 values(1);
|
|
explain select count(*) from t1;
|
|
Comment
|
|
Select tables optimized away
|
|
insert into t1 values(1);
|
|
explain select count(*) from t1;
|
|
Comment
|
|
Select tables optimized away
|
|
drop table t1;
|