select top 1 cli_no company

------解决方案--------------------

SELECT a.list_no, a.prod_no, a.batch_no, a.inv_num, a.sell_price,b.cli_no as md_no, e.cli_no, e.cli_name, e.cli_add, e.cli_tel, e.inv_date
FROM (select top 1 cli_no company) b, dbo.inv_sub AS a LEFT OUTER JOIN
 (SELECT dbo.inv_main.list_no, dbo.inv_main.cli_no, dbo.client.cli_name, dbo.client.cli_add, dbo.client.cli_tel, dbo.inv_main.inv_date
 FROM dbo.inv_main LEFT OUTER JOIN
 dbo.client ON dbo.inv_main.cli_no = dbo.client.cli_no) AS e ON a.list_no = e.list_no


楼主为何既 from a,b 又 from a left join b 的。

SELECT a.list_no, a.prod_no, a.batch_no, a.inv_num, a.sell_price,b.cli_no as md_no, e.cli_no, e.cli_name, e.cli_add, e.cli_tel, e.inv_date
FROM (select top 1 cli_no from company) b cross join dbo.inv_sub AS a LEFT OUTER JOIN
 (SELECT dbo.inv_main.list_no, dbo.inv_main.cli_no, dbo.client.cli_name, dbo.client.cli_add, dbo.client.cli_tel, dbo.inv_main.inv_date
 FROM dbo.inv_main LEFT OUTER JOIN
 dbo.client ON dbo.inv_main.cli_no = dbo.client.cli_no) AS e ON a.list_no = e.list_no

试试。

------解决方案--------------------

SELECT a.list_no, a.prod_no, a.batch_no, a.inv_num, a.sell_price,b.cli_no as md_no, e.cli_no, e.cli_name, e.cli_add, e.cli_tel, e.inv_date
FROM (select top 1 cli_no company) b cross join dbo.inv_sub AS a LEFT OUTER JOIN
 (SELECT dbo.inv_main.list_no, dbo.inv_main.cli_no, dbo.client.cli_name, dbo.client.cli_add, dbo.client.cli_tel, dbo.inv_main.inv_date
 FROM dbo.inv_main LEFT OUTER JOIN
 dbo.client ON dbo.inv_main.cli_no = dbo.client.cli_no) AS e ON a.list_no = e.list_no

------解决方案--------------------

其实原因很简单，单看这里FROM (select top 1 cli_no company) b, dbo.inv_sub AS a 就能发现，由于后面没有on子句，因此这里其实执行的是cross join，换句话说，由于你采用以前的写法select * from table1,table2如果后面没有on子句，SQL就自动按照cross join来执行了。
为了更好的说明问题，可以参考下面的代码：
SQL code

CREATE TABLE t1
(
    id INT
)
INSERT INTO t1
SELECT 1
CREATE TABLE t2
(
    id INT
)
INSERT INTO t2
SELECT 2 UNION ALL
SELECT 3 UNION ALL
SELECT 4 UNION ALL
SELECT 5
CREATE TABLE t3
(
    id INT