sql差异

类别	MS SQL Server	My SQL	PG SQL	Oracle	Access
自增	identity(1,1)	auto_increment ALTER TABLE 'tableName' AUTO_INCREMENT=100
日期	getdate(),getutcdate()	now(),utc_timestamp()
执行储存过程	exec(ute)	call
存储过程跳出	return	不能使用return
字符串相加	'1'+'2'	concat('1','2')		|| 或 concat
dual表	x	select 1 (from dual where 1>0)		select 1 from dual	x
update行数据	同时	更新依次从左到右		同时
通配符	% 任意长度，_ 单个字符	% 任意长度，_ 单个字符		% 任意长度，_ 单个字符	* 任意长度，? 单个字符
取模	7%6	7%6		MOD(7,6)	7 MOD 6
星期几	DATEPART(DW,date)	DAYOFWEEK(data)		TO_CHAR(date,'D')	DatePart('w',date)
自然对数	LOG	LN		LN	LOG
True	1	1		1	-1
唯一码	NewID()	UUID()		SYS_GUID()
后n行	借助top	offset n		借助rownum
更改表名	EXEC sp_rename 'table1', 'table2';	rename table table1 to table2;		alter table table1 rename to table2
更改字段名	EXEC sp_rename N'dbo.test_tab.val', N'val2', 'COLUMN'	alter table t change physics physisc char(10);
使用关键字	[type]			"type"
默认时间	datetime getDate()	TIMESTAMP  CURRENT_TIMESTAMP()
between and范围	0<=x<=1	0<=x<=1
参数符号	@id	?id		:id	?
列信息	SELECT c.name AS ColumnName , ISNULL(TYPE_NAME(c.system_type_id), t.name) AS DataType , COLUMNPROPERTY(c.object_id, c.name, 'charmaxlen') AS DataLength , c.is_nullable AS IsNullable , g.[value] AS Description FROM sys.columns c INNER JOIN sys.objects o ON c.object_id = o.object_id AND o.type = 'U' LEFT JOIN sys.types t ON c.user_type_id = t.user_type_id LEFT JOIN sys.extended_properties g ON c.object_id = g.major_id AND c.column_id = g.minor_id WHERE o.name = 'a';	show full columns in {0};	select distinct column_name, format_type(atttypid, atttypmod) dataType, is_nullable, description, (pg_attribute.attnum =Any(pg_constraint.conkey)) isPrimaryKey, col.ordinal_position from  pg_class c  inner join information_schema.columns col on c.relname=col.table_name left join pg_description d on c.oid=d.objoid  and col.ordinal_position =d.objsubid left join pg_constraint on pg_constraint.conrelid = c.oid and pg_constraint.contype='p' left join pg_attribute on pg_attribute.attrelid = c.oid  and pg_attribute.attname=col.column_name where c.relname='{0}' order by ordinal_position;
修改列默认值	ALTER TABLE dbo.T_Product ADD CONSTRAINT DF_T_Product_ProductSort DEFAULT 0 FOR ProductSort
查询表是否存在	--如果是实表可以用 if exists (select * from sysobjects where id = object_id(N'[dbo].[表名]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [dbo].[表名] --如果是临时表可以用 if object_id('tempdb..##temp') is not null    drop table ##temp
删除索引	DROP INDEX index_name ON table_name	ALTER TABLE table_name DROP INDEX index_name		DROP INDEX index_name	DROP INDEX index_name ON table_name
复制表结构	select * into newTable from table where 1=0	create table newTable like table
库存在	if exists(select * from master..sysdatabases where name=N'库名')
存储过程是否存在	if exists(select 1 from sysobjects where id=object_id('所有者.存储过程名') and xtype='P')    print '存在'    else    print '不存在'
视图存在	--SQL Server 2000  IF EXISTS (SELECT * FROM sysviews WHERE object_id = '[dbo].[视图名]'  --SQL Server 2005  IF EXISTS (SELECT * FROM sys.views WHERE object_id = '[dbo].[视图名]'
函数名是否存在	if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[函数名]') and xtype in (N'FN', N'IF', N'TF'))