mirror of
https://github.com/MariaDB/server.git
synced 2025-11-03 14:33:32 +03:00
220 lines
5.4 KiB
Plaintext
220 lines
5.4 KiB
Plaintext
drop table if exists t1;
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create table t1 (a int not null,b int not null, primary key (a)) type=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 NULL 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)) type=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)) type=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, type=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) type=heap;
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insert into t1 values (869751),(736494),(226312),(802616);
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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 type=myisam;
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explain select * from t1 where a in (869751,736494,226312,802616);
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table type possible_keys key key_len ref rows Extra
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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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type=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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table type possible_keys key key_len ref rows Extra
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t1 ALL x NULL NULL NULL 6
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t2 eq_ref y y 4 t1.x 1
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drop table t1;
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create table t1 (a int) type=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) ) TYPE=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)) type=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) type=heap;
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drop table t1;
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create table t1 (n int) type=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)) type=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)) type=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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table type possible_keys key key_len ref rows Extra
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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=btn;
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explain select * from t1 where btn="a";
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table type possible_keys key key_len ref rows Extra
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t1 ALL btn NULL NULL NULL 11 Using where
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explain select * from t1 where btn="a" and new_col="a";
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table type possible_keys key key_len ref rows Extra
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t1 ref btn btn 11 const,const 10 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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) type=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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table type possible_keys key key_len ref rows Extra
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t1 ref a a 5 const 10 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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table type possible_keys key key_len ref rows Extra
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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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Duplicate entry '3' for key 1
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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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) TYPE=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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table type possible_keys key key_len ref rows Extra
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t1 ref a a 5 const 10 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)) type=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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