数据库学习杂项

纯随笔....

--查看表的定义 
sp_help
exec sp_help 't_users'
 
--查看表中的数据 
SELECT * from t_users
 
--获取有关表的信息 
SELECT * from sys.tables
 
--获取有关表列的信息 
SELECT * from sys.columns where object_id in (SELECT object_id from sys.tables)
SELECT COLUMNPROPERTY( OBJECT_ID('t_zichan'),N'f_zcid','PRECISION')
SELECT OBJECT_ID('t_zichan')

--获取有关将要计算的表列的信息 
SELECT * from sys.computed_columns
 
--查看表的依赖关系 
sys.sql_dependencies (Transact-SQL)

--TRUNCATE TABLE 在功能上与没有 WHERE 子句的 DELETE 语句相同 但是TRUNCATE TABLE 速度更快
--TRUNCATE TABLE t_zichan

--自定义主键id需先identity_insert '主键' on 才可以
set identity_insert '主键' on
insert into 表('主键') values('111')

--用户与进程信息
exec sp_who
exec sp_who2

--top 50 percent = 50% ,top 2 with ties 最后一条相同的都查出
select top 50 percent * from t_zichan
select top 2 with ties * from t_zichan order by f_zcsl desc

--不重复记录
select distinct f_zczwsl from t_zichan

--标识列和GUID列
--在SQL Server的表中，可能会有两种特殊的列。一种是标识列（Identity）,一种是全球唯一标识符（GUID)
select @@identity
select IDENTITYCOL from t_zichan
select $identity from t_zichan
select $rowguid from t_zichan

--表join自己
select *
from [HongJing_data].[dbo].[t_caidan] a full join [HongJing_data].[dbo].[t_caidan] b on a.f_cdupid = b.f_cdid 

--group by汇总 :with cube,with rollup, all
select f_zcid,sum(f_zcsl),f_zczwsl from t_zichan
group by f_zczwsl,f_zcid
with cube

--compute by归类
select * from t_zichan compute sum(f_zcsl)
select * from t_zichan order by f_zcid compute sum(f_zcsl) by f_zcid

--isnull
select [f_zcid],isnull([f_zcmc],'空'),[f_zcdw],[f_zcdj],[f_zcsl],[f_zczwsl],[f_zcgmrq],[f_zccgr]
from t_zichan

--raisserror
raiserror('ddd',16,5)

--存储过程返回结果集,标量值,影响行数,错误信息
drop procedure dbo.aaa
go
create procedure dbo.aaa
as
set nocount off

declare @date date = getdate()
exec Pro_Insert_Zichan '书籍a','本',99.9,50,@date,'采购人1'
print '影响行数: '+cast(@@rowcount as varchar)

select * from t_zichan
print '影响行数: '+cast(@@rowcount as varchar)
return 5
go

drop procedure dbo.bbb
go
create procedure dbo.bbb
as
select * from t_zichan
select * from t_users
go

declare @re int = 0
exec @re = aaa
select @re

--cast 和 convert
select cast('2001-01-01 10:10:10' as time),CONVERT(date ,'2001-01-01 10:10:10')

--字符串当语句执行(ntext/nchar/nvarchar类型 N'..')
declare @sql nvarchar(100)
set @sql = N'select * from t_zichan'
select @sql
exec sp_executesql @sql
exec sp_executesql N'select * from t_zichan'