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117 lines
2.7 KiB
Plaintext
117 lines
2.7 KiB
Plaintext
create table t1(a int not null, b int, c char(10), d varchar(20), primary key (a)) engine = innodb default charset=ucs2;
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insert into t1 values (1,1,'ab','ab'),(2,2,'ac','ac'),(3,2,'ad','ad'),(4,4,'afe','afe');
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commit;
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alter table t1 add unique index (b);
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ERROR 23000: Duplicate entry '2' for key 'b'
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insert into t1 values(8,9,'fff','fff');
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select * from t1;
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a b c d
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1 1 ab ab
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2 2 ac ac
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3 2 ad ad
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4 4 afe afe
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8 9 fff fff
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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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`a` int(11) NOT NULL,
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`b` int(11) DEFAULT NULL,
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`c` char(10) DEFAULT NULL,
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`d` varchar(20) DEFAULT NULL,
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PRIMARY KEY (`a`)
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) ENGINE=InnoDB DEFAULT CHARSET=ucs2
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alter table t1 add index (b);
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insert into t1 values(10,10,'kkk','iii');
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select * from t1;
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a b c d
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1 1 ab ab
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2 2 ac ac
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3 2 ad ad
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4 4 afe afe
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8 9 fff fff
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10 10 kkk iii
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select * from t1 force index(b) order by b;
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a b c d
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1 1 ab ab
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2 2 ac ac
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3 2 ad ad
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4 4 afe afe
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8 9 fff fff
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10 10 kkk iii
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explain select * from t1 force index(b) order by b;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 index NULL b 5 NULL 6
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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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`a` int(11) NOT NULL,
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`b` int(11) DEFAULT NULL,
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`c` char(10) DEFAULT NULL,
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`d` varchar(20) DEFAULT NULL,
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PRIMARY KEY (`a`),
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KEY `b` (`b`)
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) ENGINE=InnoDB DEFAULT CHARSET=ucs2
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alter table t1 add unique index (c), add index (d);
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insert into t1 values(11,11,'aaa','mmm');
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select * from t1;
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a b c d
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1 1 ab ab
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2 2 ac ac
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3 2 ad ad
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4 4 afe afe
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8 9 fff fff
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10 10 kkk iii
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11 11 aaa mmm
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select * from t1 force index(b) order by b;
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a b c d
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1 1 ab ab
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2 2 ac ac
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3 2 ad ad
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4 4 afe afe
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8 9 fff fff
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10 10 kkk iii
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11 11 aaa mmm
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select * from t1 force index(c) order by c;
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a b c d
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11 11 aaa mmm
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1 1 ab ab
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2 2 ac ac
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3 2 ad ad
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4 4 afe afe
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8 9 fff fff
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10 10 kkk iii
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select * from t1 force index(d) order by d;
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a b c d
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1 1 ab ab
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2 2 ac ac
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3 2 ad ad
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4 4 afe afe
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8 9 fff fff
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10 10 kkk iii
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11 11 aaa mmm
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explain select * from t1 force index(b) order by b;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 index NULL b 5 NULL 7
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explain select * from t1 force index(c) order by c;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 index NULL c 21 NULL 7
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explain select * from t1 force index(d) order by d;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 index NULL d 43 NULL 7
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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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`a` int(11) NOT NULL,
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`b` int(11) DEFAULT NULL,
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`c` char(10) DEFAULT NULL,
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`d` varchar(20) DEFAULT NULL,
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PRIMARY KEY (`a`),
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UNIQUE KEY `c` (`c`),
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KEY `b` (`b`),
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KEY `d` (`d`)
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) ENGINE=InnoDB DEFAULT CHARSET=ucs2
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check table t1;
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Table Op Msg_type Msg_text
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test.t1 check status OK
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drop table t1;
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