MySQL与SQL Server的一些区别浅析_MySQL
1、mysql支持enum,和set类型,sql server不支持
2、mysql不支持nchar,nvarchar,ntext类型
3、mysql的递增语句是AUTO_INCREMENT,而mssql是identity(1,1)
4、mssql默认到处表创建语句的默认值表示是((0)),而在mysql里面是不允许带两括号的
5、mysql需要为表指定存储类型
6、mssql识别符是[],[type]表示他区别于关键字,但是mysql却是 `,也就是按键1左边的那个符号
7、mssql支持getdate()方法获取当前时间日期,但是mysql里面可以分日期类型和时间类型,获取当前日期是cur_date(),当前完整时间是 now()函数
8、mssql不支持replace into 语句,但是在最新的sql20008里面,也支持merge语法
9、mysql支持insert into table1 set t1 = ‘', t2 = ‘' ,但是mssql不支持这样写
10、mysql支持insert into tabl1 values (1,1), (1,1), (1,1), (1,1), (1,1), (1,1), (1,1)
11 mssql不支持limit语句,是非常遗憾的,只能用top 取代limt 0,N,row_number() over()函数取代limit N,M
12、mysql在创建表时要为每个表指定一个存储引擎类型,而mssql只支持一种存储引擎
13、mysql不支持默认值为当前时间的datetime类型(mssql很容易做到),在mysql里面是用timestamp类型
14、mssql里面检查是否有这个表再删除,需要这样:if exists (select * from dbo.sysobjects where id=id (N'uc_newpm') and OBJECTPROPERTY(id, N'IsUserTable') = 1) 但是在mysql里面只需要 DROP TABLE IF EXISTS cdb_forums;
15、mysql支持无符号型的整数,那么比不支持无符号型的mssql就能多出一倍的最大数存储
16、mysql不支持在mssql里面使用非常方便的varchar(max)类型,这个类型在mssql里面既可做一般数据存储,也可以做blob数据存储
17、mysql创建非聚集索引只需要在创建表的时候指定为key就行,比如:KEY displayorder (fid,displayorder) 在mssql里面必须要:
代码如下:
create unique nonclustered index index_uc_protectedmembers_username_appid on dbo.uc_protectedmembers (username asc,appid asc)
18、mysql text字段类型不允许有默认值
19、mysql的一个表的总共字段长度不超过65XXX。
20、一个很表面的区别就是mysql的安装特别简单,而且文件大小才23M左右(5.5.23),相比微软这个庞然大物,安装进度来说简直就是.....
21、mysql的管理工具有几个比较好的,mysql_front,和官方那个套件,不过都没有SSMS的使用方便,这是mysql很大的一个缺点。
22、mysql的存储过程只是出现在最新的版本中,稳定性和性能可能不如mssql。
23、同样的负载压力,mysql要消耗更少的CPU和内存,mssql的确是很耗资源。
24、php连接mysql和mssql的方式都差不多,只需要将函数的mysql替换成mssql即可,如果是PDO方式只需要把mysql替换mssql即可。
25、mysql支持date,time,year类型,mssql到2008才支持date和time。
附:MySQL与MSSQL分页的区别
之前一直用MySQL,虽然比起mssql这个庞大的数据库系统mysql很苗条,但它并不逊色。以下说说这两个在数据库各自的分页区别
例1,取出前十条
代码如下:
SELECT * FROM table LIMIT 10;
在mssql中
代码如下:
SELECT TOP 10 * FROM table
例2,每页十条,取出第三页
在MySQL中
代码如下:
SELECT * FROM table LIMIT 20,10
在mssql中
代码如下:
SELECT TOP 10 * FROM table WHERE id NOT IN(
SELECT TOP 20 id FROM table ORDER BY id DESC
) ORDER BY id DESC;
由以上例子可以看出,在MySQL中分页用LIMIT关键字,如果是LIMIT 10表示取前十条,如果是LIMIT 10,10表示偏移十条取前十条记录。在mssql中用top关键字,如果只取前n条记录直接top n即可,但是要是分页取就有点麻烦。

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