SQL SERVER 的 INFORMATION_SCHEMA 的使用

-------------------------------------------------------
第一个查询看看库里有多少个表，表名等

select * from INFORMATION_SCHEMA.TABLES;
-------------------------------------------------------
第二个查询搜索详细
 SELECT
 (case when a.colorder=1 then d.name else ‘‘ end) as 表名,--如果表名相同就返回空
     a.colorder as 字段序号,
     a.name as 字段名,
     (case when COLUMNPROPERTY( a.id,a.name,‘IsIdentity‘)=1 then ‘√‘else ‘‘ end) as 标识,
     (case when (SELECT count(*) FROM sysobjects--查询主键
                     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) as 主键,--查询主键END
 b.name as 类型,
 a.length as 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) as 允许空,
 isnull(e.text,‘‘) as 默认值,
 isnull(g.[value],‘‘) AS 字段说明
 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
 order by a.id,a.colorder