在试听中如何用SQL选中从表选取所有列

Posted 2023-05-10

参考技术A 在SQL语言中，SQL选择列表(select_list)指出所查询列。
SQL选择列表可以是一组列名列表、星号、表达式、变量(包括局部变量和全局变量)等构成。
选择所有列,例如，下面语句显示testtable表中所有列的数据：
SELECT*
FROM testtable

sql 中如何用别名作为查询条件

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