删除数据库所有的表:
declare @sql varchar(8000) while (select count(*) from sysobjects where type='U')>0 begin SELECT @sql='drop table ' + name FROM sysobjects WHERE (type = 'U') ORDER BY 'drop table ' + name exec(@sql) end
查询表的字段信息:
SELECT (case when a.colorder=1 then d.name else null end) 表名, a.colorder 字段序号,a.name 字段名, (case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then '√'else '' end) 标识, (case when (SELECT count(*) FROM sysobjects WHERE (name in (SELECT name FROM sysindexes WHERE (id = a.id) AND (indid in (SELECT indid FROM sysindexkeys WHERE (id = a.id) AND (colid in (SELECT colid FROM syscolumns WHERE (id = a.id) AND (name = a.name))))))) AND (xtype = 'PK'))>0 then '√' else '' end) 主键,b.name 类型,a.length 占用字节数, COLUMNPROPERTY(a.id,a.name,'PRECISION') as 长度, isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0) as 小数位数,(case when a.isnullable=1 then '√'else '' end) 允许空, isnull(e.text,'') 默认值,isnull(g.[value], ' ') AS [说明] FROM syscolumns a left join systypes b on a.xtype=b.xusertype inner join sysobjects d on a.id=d.id and d.xtype='U' and d.name<>'dtproperties' left join syscomments e on a.cdefault=e.id left join sys.extended_properties g on a.id=g.major_id AND a.colid=g.minor_id left join sys.extended_properties f on d.id=f.class and f.minor_id=0 where b.name is not null and d.name='tablename' order by a.id,a.colorder
http://jingyan.baidu.com/article/9c69d48f99a91b13c9024ebf.html
判断字段是否包含中文字符:
---一个中文字符占2个字节 select len(Type),datalength(Type),type from T_Visas where len(Type)=datalength(Type)
查询表中的某个列是否有重复值出现的sql语句
select 某列,COUNT(1) from table group by 某列 order by count(1)