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drop table if exists t1, t2;
create table t1 (v varchar(30), c char(3), e enum('abc','def','ghi'), t text);
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`v` VARCHAR(30) COLLATE utf8_general_ci DEFAULT NULL,
`c` VARCHAR(3) COLLATE utf8_general_ci DEFAULT NULL,
`e` ENUM('abc','def','ghi') DEFAULT NULL,
`t` TEXT COLLATE utf8_general_ci
) ENGINE=DEFAULT COLLATE = utf8_general_ci
insert into t1 values ('abc', 'de', 'ghi', 'jkl');
insert into t1 values ('abc ', 'de ', 'ghi', 'jkl ');
insert into t1 values ('abc ', 'd ', 'ghi', 'jkl ');
select length(v),length(c),length(e),length(t) from t1;
length(v) length(c) length(e) length(t)
3 2 3 3
4 3 3 4
7 3 3 7
drop table t1;
create table t1 (v varchar(20));
insert into t1 values('a ');
select v='a' from t1;
v='a'
1
select binary v='a' from t1;
binary v='a'
0
select binary v='a ' from t1;
binary v='a '
1
insert into t1 values('a');
alter table t1 add primary key (v);
ERROR 23000: Duplicate entry 'a' for key 'PRIMARY'
drop table t1;
create table t1 (v varbinary(20));
insert into t1 values('a');
insert into t1 values('a ');
alter table t1 add primary key (v);
drop table t1;
create table t1 (v varchar(254), index (v));
insert into t1 values ("This is a test ");
insert into t1 values ("Some sample data");
insert into t1 values (" garbage ");
insert into t1 values (" This is a test ");
insert into t1 values ("This is a test");
insert into t1 values ("Hello world");
insert into t1 values ("Foo bar");
insert into t1 values ("This is a test");
insert into t1 values ("MySQL varchar test");
insert into t1 values ("test MySQL varchar");
insert into t1 values ("This is a long string to have some random length data included");
insert into t1 values ("Short string");
insert into t1 values ("VSS");
insert into t1 values ("Some samples");
insert into t1 values ("Bar foo");
insert into t1 values ("Bye");
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 1019 const 1 Using where
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
alter table t1 change v v varchar(255);
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 1023 const 1 Using where
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
alter table t1 change v v varchar(256);
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 1027 const 1 Using where
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
alter table t1 change v v varchar(257);
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 1031 const 1 Using where
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
alter table t1 change v v varchar(258);
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 1035 const 1 Using where
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
alter table t1 change v v varchar(259);
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 1039 const 1 Using where
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
alter table t1 change v v varchar(258);
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 1035 const 1 Using where
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
alter table t1 change v v varchar(257);
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 1031 const 1 Using where
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
alter table t1 change v v varchar(256);
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 1027 const 1 Using where
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
alter table t1 change v v varchar(255);
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 1023 const 1 Using where
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
alter table t1 change v v varchar(254);
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 1019 const 1 Using where
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
alter table t1 change v v varchar(253);
alter table t1 change v v varchar(254), drop key v;
alter table t1 change v v varchar(300), add key (v(10));
select * from t1 where v like 'This is a test' order by v;
v
This is a test
This is a test
select * from t1 where v='This is a test' order by v;
v
This is a test
This is a test
This is a test
Warnings:
Error 1406 Data too long for column 'v' at row 1
select * from t1 where v like 'S%' order by v;
v
Short string
Some sample data
Some samples
explain select * from t1 where v like 'This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
explain select * from t1 where v='This is a test' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ref v v 43 const 1 Using where
Warnings:
Error 1406 Data too long for column 'v' at row 1
explain select * from t1 where v like 'S%' order by v;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL v NULL NULL NULL 16 Using where; Using filesort
drop table t1;
create table t1 (pkcol varchar(16), othercol varchar(16), primary key (pkcol));
insert into t1 values ('test', 'something');
update t1 set othercol='somethingelse' where pkcol='test';
select * from t1;
pkcol othercol
test somethingelse
drop table t1;
create table t1 (a int, b varchar(12));
insert into t1 values (1, 'A'), (22, NULL);
create table t2 (a int);
insert into t2 values (22), (22);
select t1.a, t1.b, min(t1.b) from t1 inner join t2 ON t2.a = t1.a
group by t1.b, t1.a;
a b min(t1.b)
22 NULL NULL
drop table t1, t2;
create table t1 (f1 varchar(6500));
create index index1 on t1(f1(10));
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`f1` VARCHAR(6500) COLLATE utf8_general_ci DEFAULT NULL,
KEY `index1` (`f1`(10))
) ENGINE=DEFAULT COLLATE = utf8_general_ci
alter table t1 modify f1 varchar(255);
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`f1` VARCHAR(255) COLLATE utf8_general_ci DEFAULT NULL,
KEY `index1` (`f1`(10))
) ENGINE=DEFAULT COLLATE = utf8_general_ci
alter table t1 modify f1 tinytext;
show create table t1;
Table Create Table
t1 CREATE TABLE `t1` (
`f1` TEXT COLLATE utf8_general_ci,
KEY `index1` (`f1`(10))
) ENGINE=DEFAULT COLLATE = utf8_general_ci
drop table t1;
DROP TABLE IF EXISTS t1;
CREATE TABLE t1(f1 VARCHAR(100) DEFAULT 'test');
INSERT INTO t1 VALUES(SUBSTR(f1, 1, 3));
DROP TABLE IF EXISTS t1;
CREATE TABLE t1(f1 CHAR(100) DEFAULT 'test');
INSERT INTO t1 VALUES(SUBSTR(f1, 1, 3));
DROP TABLE IF EXISTS t1;
drop table if exists t1, t2, t3;
create table t3 (
id int,
en varchar(255),
cz varchar(255)
);
insert into t3 (id, en, cz) values
(1,'en string 1','cz string 1'),
(2,'en string 2','cz string 2'),
(3,'en string 3','cz string 3');
create table t1 (
id int,
name_id int
);
insert into t1 (id, name_id) values (1,1), (2,3), (3,3);
create table t2 (id int);
insert into t2 (id) values (1), (2), (3);
select t1.*, t2.id, t3.en, t3.cz from t1 left join t2 on t1.id=t2.id
left join t3 on t1.id=t3.id order by t3.id;
Catalog Database Table Table_alias Column Column_alias Type Length Max length Is_null Flags Decimals Charsetnr
def test t1 t1 id id 1 11 1 Y 32768 0 63
def test t1 t1 name_id name_id 1 11 1 Y 32768 0 63
def test t2 t2 id id 1 11 1 Y 32768 0 63
def test t3 t3 en en 8 1020 11 Y 0 0 45
def test t3 t3 cz cz 8 1020 11 Y 0 0 45
id name_id id en cz
1 1 1 en string 1 cz string 1
2 3 2 en string 2 cz string 2
3 3 3 en string 3 cz string 3
drop table t1, t2, t3;
CREATE TABLE t1 (a varchar(2));
INSERT INTO t1 VALUES (10), (50), (30), ('1a'), (60), ('t');
SELECT a,(a + 0) FROM t1 ORDER BY a;
a (a + 0)
10 10
1a 1
30 30
50 50
60 60
t 0
SELECT a,(a DIV 2) FROM t1 ORDER BY a;
a (a DIV 2)
10 5
1a 0
30 15
50 25
60 30
t 0
DROP TABLE t1;
|