VARCHAR 详解

mysql> create table t1( a varchar(20));
Query OK, 0 rows affected (0.27 sec)

mysql> show create table t1;
+-------+---------------------------------------------------------------
| Table | Create Table
+-------+---------------------------------------------------------------
| t1    | CREATE TABLE `t1` (
  `a` varchar(20) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+---------------------------------------------------------------
1 row in set (0.00 sec)

mysql> insert into t1 select repeat("a",21);
ERROR 1406 (22001): Data too long for column ‘a‘ at row 1

mysql> insert into t1 select repeat("a",20);
Query OK, 1 row affected (0.09 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> insert into t1 select repeat("我",21);
ERROR 1406 (22001): Data too long for column ‘a‘ at row 1

mysql> insert into t1 select repeat("我",20);
Query OK, 1 row affected (0.11 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> insert into t1 select "我我我我我我我我我我我我我我我我我我我1";
Query OK, 1 row affected (0.09 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> insert into t1 select "我我我我我我我我我我我我我我我我我我我11";
ERROR 1406 (22001): Data too long for column ‘a‘ at row 1

mysql> show create table a;
+-------+-------------------------------------------------------------------------------------------+
| Table | Create Table                                                                              |
+-------+-------------------------------------------------------------------------------------------+
| a     | CREATE TABLE `a` (
  `a` varchar(21844) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+-------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)

mysql> create table a( a varchar(65535));
ERROR 1074 (42000): Column length too big for column ‘a‘ (max = 21845); use BLOB or TEXT instead

mysql> create table a( a varchar(65532));
ERROR 1074 (42000): Column length too big for column ‘a‘ (max = 21845); use BLOB or TEXT instead

mysql> create table a( a varchar(21845));
ERROR 1118 (42000): Row size too large. The maximum row size for the used table type, not counting BLOBs, is 65535. This includes st
eck the manual. You have to change some columns to TEXT or BLOBs

mysql> create table a( a varchar(21844));
Query OK, 0 rows affected (0.31 sec)

mysql> create table a1 ( a varchar(65535))charset=latin1;
ERROR 1118 (42000): Row size too large. The maximum row size for the used table type, not counting BLOBs,
eck the manual. You have to change some columns to TEXT or BLOBs

mysql> create table a1 ( a varchar(65534))charset=latin1;
ERROR 1118 (42000): Row size too large. The maximum row size for the used table type, not counting BLOBs,
eck the manual. You have to change some columns to TEXT or BLOBs

mysql> create table a1 ( a varchar(65533))charset=latin1;
ERROR 1118 (42000): Row size too large. The maximum row size for the used table type, not counting BLOBs,
eck the manual. You have to change some columns to TEXT or BLOBs

mysql> create table a1 ( a varchar(65532))charset=latin1;
Query OK, 0 rows affected (0.33 sec)

mysql> insert into a1 select repeat("我",65532);
ERROR 1366 (HY000): Incorrect string value: ‘\xE6\x88\x91\xE6\x88\x91...‘ for column ‘a‘ at row 1
mysql> insert into a1 select "我";
ERROR 1366 (HY000): Incorrect string value: ‘\xE6\x88\x91‘ for column ‘a‘ at row 1


mysql> insert into a1 select repeat("a",65532);
Query OK, 1 row affected (0.17 sec)
Records: 1  Duplicates: 0  Warnings: 0