Question

我在db1中有一个表t1，在t2中有另一个表db2。我在两个表中都有相同的列。

如何只检索那些不在另一个表中的行？

select id_num 
from [db1].[dbo].[Tbl1]

except 

select id_num
from [db2].[dbo].[Tb01]

Answer 1

您可以使用LEFT JOIN或WHERE NOT IN功能。

使用WHERE NOT IN：

select dbase1.id_num from [db1].[dbo].[Tbl1] as dbase1 where dbase1.id_num not in (select dbase2.id_num from [db2].[dbo].[Tb01] as dbase2)

使用LEFT JOIN（建议这样做要快得多）

SELECT dbase1.id_num FROM [db1].[dbo].[Tbl1] as dbase1 LEFT JOIN [db2].[dbo].[Tb01] as dbase2 ON dbase2.id_num COLLATE Latin1_General_CI_A = dbase1.id_num COLLATE Latin1_General_CI_A WHERE dbase2.id_num IS NULL

Answer 2

将表与DB2进行比较其他数据库可能具有select a -b语句或类似语句。因为当时我的数据库也没有a-b我使用以下内容。将语句包装在create table语句中以挖掘结果。没有行和表是相同的。我已经在BEFORE | AFTER中添加了一栏，使结果易于阅读。

SELECT 'AFTER', A.* FROM      
(SELECT * FROM &AFTER         
EXCEPT                        
 SELECT * FROM &BEFORE) AS A  
UNION                         
SELECT 'BEFORE', B.* FROM     
(SELECT * FROM &BEFORE        
EXCEPT                        
 SELECT * FROM &AFTER) AS B

如何仅检索不在另一个表（db2）中的表（db1）的那些行

2 个答案: