Mysql与其他数据库一些不同地方

1.Insert Set语句
mysql> create table wison_test1(id int,name varchar(10));
Query OK, 0 rows affected (0.10 sec)

mysql> insert into wison_test1 set id=1,name='wison';-------相对于后一条insert语句,返回的提示信息少了一行
Query OK, 1 row affected (0.08 sec)

mysql> select * from wison_test1;
+------+-------+
| id | name |
+------+-------+
| 1 | wison |
+------+-------+
1 row in set (0.00 sec)

mysql> insert into wison_test1 select 2,'Wison';
Query OK, 1 row affected (0.10 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> select * from wison_test1;
+------+-------+
| id | name |
+------+-------+
| 1 | wison |
| 2 | Wison |
+------+-------+
2 rows in set (0.00 sec)
2.数据类型带长度
mysql> create table wison_test2(id int(5));
Query OK, 0 rows affected (0.12 sec)

mysql> insert into wison_test2 select 1;
Query OK, 1 row affected (0.10 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> select * from wison_test2;
+------+
| id |
+------+
| 1 |
+------+
1 row in set (0.00 sec)

mysql> alter table wison_test2 modify id int(5) zerofill;
Query OK, 1 row affected (0.58 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> select * from wison_test2;
+-------+
| id |
+-------+
| 00001 |
+-------+
1 row in set (0.00 sec)

mysql> insert into wison_test2 select 1111111;
Query OK, 1 row affected (0.10 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> select * from wison_test2;
+---------+
| id |
+---------+
| 00001 |
| 1111111 |
+---------+
2 rows in set (0.00 sec)
3.BIT类型---直接读取会查询不出结果,需要使用hex()或者bin()
mysql> create table wison_test3(id bit(2));
Query OK, 0 rows affected (0.11 sec)

mysql> insert into wison_test3 select 1;
Query OK, 1 row affected (0.07 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> select * from wison_test3;
+------+
| id |
+------+
| |
+------+
1 row in set (0.00 sec)

mysql> select hex(id) from wison_test3;
+---------+
| hex(id) |
+---------+
| 1 |
+---------+
1 row in set (0.00 sec)

mysql> select bin(id) from wison_test3;
+---------+
| bin(id) |
+---------+
| 1 |
+---------+
1 row in set (0.00 sec)
4.TIMESTAMP类型--在Mysql中会根据当前时区不同返回不同的值
mysql> create table wison_test4(id1 timestamp,id2 datetime);
Query OK, 0 rows affected (0.09 sec)

mysql> show variables like 'time_zone';
+---------------+--------+
| Variable_name | Value |
+---------------+--------+
| time_zone | SYSTEM |
+---------------+--------+
1 row in set (0.00 sec)

mysql> insert into wison_test4 select now(),now();
Query OK, 1 row affected (0.07 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> select * from wison_test4;
+---------------------+---------------------+
| id1 | id2 |
+---------------------+---------------------+
| 2014-04-29 23:05:03 | 2014-04-29 23:05:03 |
+---------------------+---------------------+
1 row in set (0.00 sec)

mysql> set time_zone='+9:00';
Query OK, 0 rows affected (0.00 sec)

mysql> select * from wison_test4;
+---------------------+---------------------+
| id1 | id2 |
+---------------------+---------------------+
| 2014-04-30 15:05:03 | 2014-04-29 23:05:03 |
+---------------------+---------------------+
1 row in set (0.00 sec)

mysql> set time_zone='-7:00';
Query OK, 0 rows affected (0.00 sec)

mysql> select * from wison_test4;
+---------------------+---------------------+
| id1 | id2 |
+---------------------+---------------------+
| 2014-04-29 23:05:03 | 2014-04-29 23:05:03 |
+---------------------+---------------------+
1 row in set (0.00 sec)
5.CHAR数据类型---CHAR会自动将后面的空格截断,VARCHAR会保留空格
mysql> create table wison_test5(c1 char(5),c2 varchar(5));
Query OK, 0 rows affected (0.11 sec)

mysql> insert into wison_test5 select 'a ','a ';
Query OK, 1 row affected (0.08 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> select * from wison_test5;
+------+------+
| c1 | c2 |
+------+------+
| a | a |
+------+------+
1 row in set (0.00 sec)

mysql> select length(c1),length(c2) from wison_test5;
+------------+------------+
| length(c1) | length(c2) |
+------------+------------+
| 1 | 3 |
+------------+------------+
1 row in set (0.00 sec)

mysql> select concat(c1,'+'),concat(c2,'+') from wison_test5;
+----------------+----------------+
| concat(c1,'+') | concat(c2,'+') |
+----------------+----------------+
| a+ | a + |
+----------------+----------------+
1 row in set (0.00 sec)
6.ENUM类型---插入的值可以是在枚举的列表中,可以写明值,或者对应的顺序编号(比如3的意思就是第三个值),NULL(插入之后仍为NULL),传入不存在的值插入的是空格
mysql> create table wison_test6(country ENUM('CN','US','TW','RU','BR'));
Query OK, 0 rows affected (0.09 sec)
mysql> insert into wison_test6 values ('CN'),('US'),('1'),('3'),('4'),(2),(NULL);
Query OK, 7 rows affected (0.06 sec)
Records: 7 Duplicates: 0 Warnings: 0

mysql> select * from wison_test6;
+---------+
| country |
+---------+
| CN |
| US |
| CN |
| TW |
| RU |
| US |
| NULL |
+---------+
7 rows in set (0.00 sec)

mysql> insert into wison_test6 select 'CA';
Query OK, 1 row affected, 1 warning (0.06 sec)
Records: 1 Duplicates: 0 Warnings: 1

mysql> show warnings;
+---------+------+----------------------------------------------+
| Level | Code | Message |
+---------+------+----------------------------------------------+
| Warning | 1265 | Data truncated for column 'country' at row 1 |
+---------+------+----------------------------------------------+
1 row in set (0.00 sec)

mysql> select * from wison_test6;
+---------+
| country |
+---------+
| CN |
| US |
| CN |
| TW |
| RU |
| US |
| NULL |
| |
+---------+
8 rows in set (0.00 sec)

另一个例子----可以看到当枚举值背身为数字时,当insert的value没包含'',则表示是第几个枚举值,否则插入的值为insert的对应值.
mysql> create table wison_test7(id ENUM('1','2','4','3','5'));
Query OK, 0 rows affected (0.07 sec)

mysql> insert into wison_test7 values('1'),('3'),(3),('4'),(4);
Query OK, 5 rows affected (0.07 sec)
Records: 5 Duplicates: 0 Warnings: 0

mysql> select * from wison_test7;
+------+
| id |
+------+
| 1 |
| 3 |
| 4 |
| 4 |
| 3 |
+------+
5 rows in set (0.00 sec)

7.在Mysql中，如果列上有索引，无需先Drop Index，可直接修改列。这点与MSSQL不一致。如下：

mysql> create table test1(id int,name char(5));
Query OK, 0 rows affected (0.30 sec)

mysql> create index ix_test1_name on test1(name);
Query OK, 0 rows affected (0.21 sec)
Records: 0 Duplicates: 0 Warnings: 0

mysql> show create table test1;
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
| test1 | CREATE TABLE `test1` (
`id` int(11) DEFAULT NULL,
`name` char(5) DEFAULT NULL,
KEY `ix_test1_name` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+--------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> alter table test1 modify name char(10);
Query OK, 0 rows affected (0.54 sec)
Records: 0 Duplicates: 0 Warnings: 0

mysql> show create table test1;
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------+
| test1 | CREATE TABLE `test1` (
`id` int(11) DEFAULT NULL,
`name` char(10) DEFAULT NULL,
KEY `ix_test1_name` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)