--比如说要判断表A中的字段C是否存在两个方法: 一, IF EXISTS ( FROM SYSOBJECTS T1 INNER JOIN SYSCOLUMNS T2 ON T1.ID=T2.ID WHERE T1.NAME='A' AND T2.NAME='C' ) PRINT '存在' ELSE PRINT '不存在' 二, 短小精悍,可谓精典 IF COL_LENGTH('A', 'C') IS NOT NULL PRINT N'存在' ELSE PRINT N'不存在' 方法一: sel
SQL查询一个表中类别字段中Max()最大值对应的记录 SELECT A.id, A.name, A.version FROM DOC A, (SELECT id, MAX(version) AS version FROM DOC GROUP BY id) AS B WHERE A.id = B.id AND A.version = B.version
功能:判断表中是否存在某字段,若不存在,则新增该字段 语句: IF NOT EXIST (SELECT 1 FROM [DATABASE].[SCHEMA].SYSCOLUMNS WHERE ID=OBJECT_ID([DATABASE].[SCHEMA].[TABLENAME]) AND NAME='COLUMN_NAME') ALTER TABLE [TABLENAME] ADD [COLUMN_NAME] [COLUMN_TYPE] p.s. 之前sql server在当前数据库下,Obj
一.比如说要判断表A中的字段C是否存在两个方法: (1) 直接查表——有点笨,有点常规 IF EXISTS ( SELECT 1 FROM SYSOBJECTS T1 INNER JOIN SYSCOLUMNS T2 ON T1.ID=T2.ID WHERE T1.NAME='A' AND T2.NAME='C' ) PRINT '存在' ELSE PRINT '不存在' (2) 直接判断列长度的函数——短小精悍,可谓精典 IF COL_LENGTH('A', 'C') IS NOT NULL
--比如说要判断表A中的字段C是否存在两个方法: 一, IF EXISTS ( SELECT 1 FROM SYSOBJECTS T1 INNER JOIN SYSCOLUMNS T2 ON T1.ID=T2.ID WHERE T1.NAME='A' AND T2.NAME='C' ) PRINT '存在' ELSE PRINT '不存在' 二, 短小精悍,可谓精典 IF COL_LENGTH('A', 'C') IS NOT NULL PRINT N'存在' ELSE PRINT N'不存在'
declare @tablename varchar(200)declare @sql varchar(2000)declare cur_t cursor forselect name from sysobjects where xtype= 'U ' and status> =0 and name not in (select name from sysobjects where id in (select id from syscolumns where id in (select id f
USE BookDiscuss DECLARE @num INT DECLARE @numdiff INT DECLARE @table VARCHAR(50) DECLARE @sql VARCHAR(8000) SET @numdiff=3 SET @num=0 WHILE @num<@numdiff BEGIN SET @table='DiscussPost_'+CAST(@num AS VARCHAR(10)); SET @sql= '
一.创建表 create table stuUnion ( sid int identity primary key, cid int, id ) ) 二.添加数据 insert into stuUnion ,'a' union ,'b' union ,'c' union ,'d' union ,'e' union ,'f' union ,'g' 三.用标量函数查询 ()创建标量函数 create function b(@cid int) ) as begin ) select @s=isnul
方法一 DELETE FROM A WHERE `name` in ( SELECT a.name FROM( SELECT name FROM A a GROUP BY name HAVING COUNT(`name`)>1 )a) AND id NOT IN( SELECT b.mid FROM (SELECT MAX(`id`) AS mid FROM A b GROUP BY `name` HAVING COUNT(`name`)>1)b) ; 方法二 DELETE FROM A WH
sql某一表中重复某一字段重复记录查询与处理 1.查询出重复记录 select 重复记录字段 form 数据表 group by houseno having count(重复记录字段)>1 2.重复记录只显示一条ID值最小或最大的记录 select id,* from 数据表 where houseno (select 重复记录字段 form 数据表 group by 重复记录 字段 having count(重复记录字段)>1 ) 这样把houseno重复的的ID值全部显示
1.删除没有默认值的列:alter table Test drop COLUMN BazaarType 2.删除有默认值的列:先删除约束(默认值)alter table Test DROP CONSTRAINT DF__Test__BazaarType__3C4ACB5F(alter table Test DROP COLUMN BazaarType 提示报错就是 DF__SheetTest__Attac__0F8D3381) 然后在删除列 alter table Test DROP COLUM
--复制另一个数据库中的某张表的结构及数据--select * from Test.dbo.TestTable(查询表中所有数据) --into [表名] 插入当前数据库新表,如果没有该表就创建 select * into TestCopy from Test.dbo.TestTable --只复制表结构(1!=1等价于1<>1,只要where后的为false就可以)--把查询出的数据插入到新表,如果没有数据就只是复制表结构了select * into TestCopy from Test.d
需要包括有几种情况一.A表中有的字段B表无二.B表有的A表无三.两个表字段名不一致的 ------------------------------------------------------------------------ 如果只对比字段名,可以这样 一.A表中有的字段B表无select name from syscolumns where id=object_id('A') and name not in(select name from syscolumns where id=obj