1
select
2 ( case when a.colorder = 1 then d.name else '' end ) 表名,
3 a.colorder 字段序号,
4 a.name 字段名,
5 ( case when COLUMNPROPERTY (a.id,a.name,'isidentity') = 1 then '√' else '' end ) 标识,
6 ( case when (
7 select count(*) from sysobjects
8 where name in (
9 select name from sysindexes
10 where (id = a.id ) and ( indid in
11 (select indid from sysindexkeys where
12 ( id = a.id ) and ( colid in (
13 select colid from syscolumns
14 where ( id = a.id ) and ( name = a.name ))))))
15 and ( xtype ='PK')) > 0 then '√' else '' end ) 主键,
16 b.name 类型,
17 a.length 字节数,
18 COLUMNPROPERTY ( a.id,a.name ,'PRECISION' ) as 长度,
19 isnull ( COLUMNPROPERTY ( a.id,a.name ,'Scale'),0) as 小数位数,
20 (case when a.isnullable = 1 then '√' else '' end ) 允许空,
21 isnull ( e.text,'') 默认值,
22 isnull (g.[value],'' ) as 字段说明
23from syscolumns a left join systypes b
24on a.xtype = b.xusertype
25inner join sysobjects d
26on a.id = d.id and d.xtype='U' and d.name <> 'dtproperties'
27left join syscomments e
28on a.cdefault = e.id
29left join sysproperties g
30on a.id = g.id and a.colid = g.smallid
31order by a.id ,a.colorder
select 2
( case when a.colorder = 1 then d.name else '' end ) 表名,3
a.colorder 字段序号,4
a.name 字段名,5
( case when COLUMNPROPERTY (a.id,a.name,'isidentity') = 1 then '√' else '' end ) 标识,6
( case when ( 7
select count(*) from sysobjects8
where name in (9
select name from sysindexes10
where (id = a.id ) and ( indid in 11
(select indid from sysindexkeys where12
( id = a.id ) and ( colid in (13
select colid from syscolumns14
where ( id = a.id ) and ( name = a.name ))))))15
and ( xtype ='PK')) > 0 then '√' else '' end ) 主键,16
b.name 类型,17
a.length 字节数,18
COLUMNPROPERTY ( a.id,a.name ,'PRECISION' ) as 长度,19
isnull ( COLUMNPROPERTY ( a.id,a.name ,'Scale'),0) as 小数位数,20
(case when a.isnullable = 1 then '√' else '' end ) 允许空,21
isnull ( e.text,'') 默认值,22
isnull (g.[value],'' ) as 字段说明23
from syscolumns a left join systypes b24
on a.xtype = b.xusertype25
inner join sysobjects d26
on a.id = d.id and d.xtype='U' and d.name <> 'dtproperties'27
left join syscomments e28
on a.cdefault = e.id29
left join sysproperties g30
on a.id = g.id and a.colid = g.smallid31
order by a.id ,a.colorder从这个 sql 语句我学到的东西：
1、case when ... then ... else ... end ：选择语句用在 select 语句中，可以将原来用0,1这样的描述信息，转换为实际的含义，而不要在程序中根据查询出来的结果再进行判断。这个可以理解为简单的数据格式化吧。如这条sql 语句中出现的 case when a.isnullable = 1 then '√' else '' end 将数据库从存储的 0,1 转换为了 '√' 和''；
2、left join ：使用这种连接方式可以使查询结果描述出一种包含关系。
3、isnull 函数：ISNULL ( check_expression , replacement_value ) ,作用是使用指定的替换值替换 NULL，例如下面的 SQL 语句中如果一本书的名称为 null ，则将价格设置为 0.00。
1SELECT SUBSTRING(title, 1, 15) AS Title, type AS Type,
2 ISNULL(price, 0.00) AS Price
3FROM titles
4
SELECT SUBSTRING(title, 1, 15) AS Title, type AS Type, 2
ISNULL(price, 0.00) AS Price3
FROM titles4
4、当然，最重要的是学到这个列出数据库表信息（包括表名、字段名、是否标识、是否主键、字段类型、字节数、长度、小数位数、允许空、默认值、字段说明）的 SQL 语句。^_^
