c#获取数据库

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1、获取所有用户名:
     Select name FROM Sysusers where status='2' and islogin='1'
     islogin='1'   :表示帐户
     islogin='0'   :表示角色
     status='2'   :表示用户帐户
     status='0'   :表示糸统帐户

2、获取所有数据库名:
Select Name FROM Master..SysDatabases orDER BY Name

3、获取所有表名:
     Select Name FROM DatabaseName..SysObjects Where XType='U' orDER BY Name
     XType='U'    :表示所有用户表;
     XType='S'    :表示所有系统表;

4、获取所有字段名:
Select Name FROM SysColumns Where id=Object_Id('表名'')

5、获取数据库所有类型:
select name from systypes

6、获取主键字段:
Select name FROM SysColumns Where id=Object_Id('表名') and colid=(select top 1 keyno from sysindexkeys where id=Object_Id('表名'))

7、获取表字段的基本信息:
程序代码
Select
字段名=rtrim(b.name),
主键=CASE WHEN h.id IS NOT NULL THEN 'PK' ELSE '' END,
字段类型=type_name(b.xusertype)+CASE WHEN b.colstat&1=1 THEN '[ID(' + CONVERT(varchar, ident_seed(a.name))+','+CONVERT(varchar,ident_incr(a.name))+')]' ELSE '' END,
长度=b.length,
允许空=CASE b.isnullable WHEN 0 THEN 'N' ELSE 'Y' END,
默认值=isnull(e.text, ''),
字段说明=isnull(c.value, '')
FROM sysobjects a, syscolumns b
LEFT OUTER JOIN sysproperties c ON b.id = c.id AND b.colid = c.smallid
LEFT OUTER JOIN syscomments e ON b.cdefault = e.id
LEFT OUTER JOIN (Select g.id, g.colid FROM sysindexes f, sysindexkeys g Where (f.id=g.id)AND(f.indid=g.indid)AND(f.indid>0)AND(f.indid<255)AND(f.status&2048) <>0) h ON (b.id=h.id)AND(b.colid=h.colid)
Where (a.id=b.id)AND(a.id=object_id('要查询的表')) --要查询的表改成你要查询表的名称
orDER BY b.colid

程序代码
Select
表名=case when a.colorder=1 then d.name else '' end,
表说明=case when a.colorder=1 then isnull(f.value,'') else '' end,
字段序号=a.colorder,
字段名=a.name,
标识=case when COLUMNPROPERTY(a.id,a.name,'IsIdentity')=1 then '√' else '' end,
主键=case when exists(Select 1 FROM sysobjects where xtype='PK' and name in (Select name FROM sysindexes Where indid in(Select indid FROM sysindexkeys Where id=a.id AND colid=a.colid))) then '√' else '' end,
类型=b.name,
字段长度=a.length,
占用字节数=COLUMNPROPERTY(a.id,a.name,'PRECISION'),
小数位数=isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0),
允许空=case when a.isnullable=1 then '√'else '' end,
默认值=isnull(e.text,''),
字段说明=isnull(g.[value],'')
FROM syscolumns a
left join systypes b on a.xusertype=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 sysproperties g on (a.id=g.id)and(a.colid=g.smallid)
left join sysproperties f on (d.id=f.id)and(f.smallid=0)
--where d.name='要查询的表' --如果只查询指定表,加上此条件
order by a.id,a.colorder

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