drop table if exists t1, t2;
create table t1 (v varchar(30), c char(3), e enum('abc','def','ghi'), t text);
truncate table vchar;
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `v` varchar(30) DEFAULT NULL,
  `c` char(3) DEFAULT NULL,
  `e` enum('abc','def','ghi') DEFAULT NULL,
  `t` text
) ENGINE=MyISAM DEFAULT CHARSET=latin1
show create table vchar;
Table	Create Table
vchar	CREATE TABLE `vchar` (
  `v` varchar(30) DEFAULT NULL,
  `c` char(3) DEFAULT NULL,
  `e` enum('abc','def','ghi') DEFAULT NULL,
  `t` text
) ENGINE=MyISAM DEFAULT CHARSET=latin1
insert into t1 values ('abc', 'de', 'ghi', 'jkl');
insert into t1 values ('abc ', 'de ', 'ghi', 'jkl ');
insert into t1 values ('abc    ', 'd  ', 'ghi', 'jkl    ');
insert into vchar values ('abc', 'de', 'ghi', 'jkl');
insert into vchar values ('abc ', 'de ', 'ghi', 'jkl ');
insert into vchar 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	2	3	4
7	1	3	7
select length(v),length(c),length(e),length(t) from vchar;
length(v)	length(c)	length(e)	length(t)
3	2	3	3
3	2	3	4
3	1	3	7
alter table vchar add i int;
show create table vchar;
Table	Create Table
vchar	CREATE TABLE `vchar` (
  `v` varchar(30) DEFAULT NULL,
  `c` char(3) DEFAULT NULL,
  `e` enum('abc','def','ghi') DEFAULT NULL,
  `t` text,
  `i` int(11) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1
select length(v),length(c),length(e),length(t) from vchar;
length(v)	length(c)	length(e)	length(t)
3	2	3	3
3	2	3	4
3	1	3	7
drop table t1, vchar;
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	257	NULL	3	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	257	const	3	100.00	Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	257	NULL	2	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	258	NULL	3	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	258	const	3	100.00	Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	258	NULL	2	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	259	NULL	3	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	259	const	3	100.00	Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	259	NULL	2	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	260	NULL	3	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	260	const	3	100.00	Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	260	NULL	2	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	261	NULL	3	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	261	const	3	100.00	Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	261	NULL	2	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	262	NULL	3	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	262	const	3	100.00	Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	262	NULL	2	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	261	NULL	3	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	261	const	3	100.00	Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	261	NULL	2	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	260	NULL	3	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	260	const	3	100.00	Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	260	NULL	2	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	259	NULL	3	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	259	const	3	100.00	Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	259	NULL	2	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	258	NULL	3	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	258	const	3	100.00	Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	258	NULL	2	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	257	NULL	3	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	257	const	3	100.00	Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	257	NULL	2	100.00	Using where; Using index
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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
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	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	13	NULL	4	100.00	Using where; Using filesort
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v='This is a test' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	ref	v	v	13	const	4	100.00	Using where
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` = 'This is a test') order by `test`.`t1`.`v`
explain select * from t1 where v like 'S%' order by v;
id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	SIMPLE	t1	NULL	range	v	v	13	NULL	2	100.00	Using where; Using filesort
Warnings:
Note	1003	/* select#1 */ select `test`.`t1`.`v` AS `v` from `test`.`t1` where (`test`.`t1`.`v` like 'S%') order by `test`.`t1`.`v`
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(65500));
create index index1 on t1(f1(10));
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `f1` varchar(65500) DEFAULT NULL,
  KEY `index1` (`f1`(10))
) ENGINE=MyISAM DEFAULT CHARSET=latin1
alter table t1 modify f1 varchar(255);
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `f1` varchar(255) DEFAULT NULL,
  KEY `index1` (`f1`(10))
) ENGINE=MyISAM DEFAULT CHARSET=latin1
alter table t1 modify f1 tinytext;
show create table t1;
Table	Create Table
t1	CREATE TABLE `t1` (
  `f1` tinytext,
  KEY `index1` (`f1`(10))
) ENGINE=MyISAM DEFAULT CHARSET=latin1
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(11),
en varchar(255) character set utf8,
cz varchar(255) character set utf8
);
truncate table t3;
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(11),
name_id int(11)
);
insert into t1 (id, name_id) values (1,1), (2,3), (3,3);
create table t2 (id int(11));
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	3	11	1	Y	32768	0	63
def	test	t1	t1	name_id	name_id	3	11	1	Y	32768	0	63
def	test	t2	t2	id	id	3	11	1	Y	32768	0	63
def	test	t3	t3	en	en	253	255	11	Y	0	0	8
def	test	t3	t3	cz	cz	253	255	11	Y	0	0	8
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 CHAR(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
Warnings:
Warning	1292	Truncated incorrect DOUBLE value: '1a'
Warning	1292	Truncated incorrect DOUBLE value: 't '
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
Warnings:
Warning	1292	Truncated incorrect DECIMAL value: '1a'
Warning	1366	Incorrect DECIMAL value: '0' for column '' at row -1
Warning	1292	Truncated incorrect DECIMAL value: 't '
SELECT a,CAST(a AS SIGNED) FROM t1 ORDER BY a;
a	CAST(a AS SIGNED)
10	10
1a	1
30	30
50	50
60	60
t	0
Warnings:
Warning	1292	Truncated incorrect INTEGER value: '1a'
Warning	1292	Truncated incorrect INTEGER value: 't'
DROP TABLE t1;
CREATE TABLE t1 (a VARCHAR(16));
INSERT INTO t1 VALUES ('5'), ('s'), ('');
SELECT 5 = a FROM t1;
5 = a
1
0
0
Warnings:
Warning	1292	Truncated incorrect DOUBLE value: 's'
DROP TABLE t1;
CREATE TABLE t1 (a CHAR(16));
INSERT INTO t1 VALUES ('5'), ('s'), ('');
SELECT 5 = a FROM t1;
5 = a
1
0
0
Warnings:
Warning	1292	Truncated incorrect DOUBLE value: 's               '
DROP TABLE t1;