转：SQLSERVER查询数据库名，表名和字段名

转 https://www.cnblogs.com/yunlongaimeng/p/15702098.html

1.获取所有数据库名:
SELECT Name FROM Master..SysDatabases ORDER BY Name
2.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;
3.获取所有字段名:
SELECT Name FROM SysColumns WHERE id=Object_Id('TableName')

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 parent_obj = a.id 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,
    占用字节数 = a.length,
    长度 = 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
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.major_id and f.minor_id = 0
where
    d.name = 'tablename'--如果只查询指定表,加上此where条件，tablename是要查询的表名；去除where条件查询所有的表信息
order by
    a.id,a.colorder