sql 中如何用别名作为查询条件

Posted 2023-03-17

两个sql语句是用union连接的，例如:
select a.id as 'id',a.membername as 'name' b.suppliername as 'companyname' from member a
inner join supplier b on a.supplierid=b.supplierid where company like'%某某%'
union
select a.id as 'id',a.membername as 'name' b.customername as 'companyname' from member a
inner join customer b on a.customerid=b.customerid where companyname like '%某某%'
像这样的查询怎么用别名作为查询条件啊

SQL Server 2005/2008
Oracle 10/11

可以用 CTE， 来 “曲线”的实现这个要求.

例如：

1> with myCTE AS (
2> SELECT 1+2+3+4 AS 别名 UNION ALL
3> SELECT 2+3+4+5 AS 别名
4> )
5> SELECT * FROM myCTE WHERE 别名 = 10
6> go
别名
-----------
10

(1 行受影响) 参考技术A select * from (select a.id as 'id',a.membername as 'name' b.suppliername as 'companyname' from member a
inner join supplier b on a.supplierid=b.supplierid
union
select a.id as 'id',a.membername as 'name' b.customername as 'companyname' from member a
inner join customer b on a.customerid=b.customerid) a where companyname like '%某某%'本回答被提问者采纳

微软的sql2005中如何用SQL语句查询出将一个表的字段的说明

查询列信息的
--isnull函数：需要个参数，如果第一个参数为空，则赋值第二个参数。
SELECT
--空格代表as关键字
(case when a.colorder=1 then d.name else '' 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 'true' else 'false' 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 'true'else 'false' end) 允许空,
isnull(e.text,'') 默认值, isnull(g.[value],'') AS 字段说明
--a代表列集合表：为每个表和视图中的每列返回一行，并为数据库中的存储过程的每个参数返回一行
--b代表列类型表：为数据库中定义的每种系统提供的数据类型和每种用户定义的数据类型返回一行。
FROM syscolumns a left join systypes b
on a.xtype=b.xusertype
--d代表对象表：在数据库中创建的每个对象（例如约束、默认值、日志、规则以及存储过程）都对应一行
inner join sysobjects d
on a.id=d.id and d.xtype='U' and d.name<>'dtproperties'
--e代表e.text是默认值：包含数据库中每个视图、规则、默认值、触发器、CHECK 约束、DEFAULT 约束和存储过程的项
left join syscomments e
on a.cdefault=e.id
--g代表g.[value]是字段说明：针对当前数据库中的每个扩展属性返回一行。
left join sys.extended_properties g
on a.id=g.major_id AND a.colid = g.major_id
order by a.id,a.colorder 参考技术A sp_help 表名追问

这个不行，没有说明的这个字段显示

追答

SELECT
a.colorder AS 字段序号, a.name AS 字段名, ISNULL(c.[value], '') AS 字段说明
FROM dbo.syscolumns a LEFT OUTER JOIN
dbo.sysobjects b ON a.id = b.id AND b.xtype = 'U' AND
b.status >= 0 LEFT OUTER JOIN
sys.extended_properties c ON a.id = c.major_id AND a.colid = c.minor_id AND
c.name = 'MS_Description'
WHERE b.name=N'表名'