[英]How to find the difference between two tables?
I have a MySQL database ver 5.1. 我有一个MySQL数据库5.1版。 I have two tables Table_A will always keep the records in it. 我有两个表Table_A始终将记录保留在其中。 Table_B will be used to only compare the differences. Table_B将仅用于比较差异。 Is there a MySQL query function via PHP that will compare the rows and tell me what rows are missing on Table_B . 是否有通过PHP的MySQL查询函数,该函数将比较行并告诉我Table_B缺少哪些行。
Table_A 表_A
user name
1 bob
1 joe
1 sally
1 matt
Table_B 表_B
user name
1 bob
1 joe
1 sally
1 john
When the PHP query was run how would I compare Table_A vs Table_B ? 运行PHP查询时,如何比较Table_A和Table_B ? All I need is to tell me that matt
no longer exists and it will add john
to Table_A . 所有我需要的是告诉我, matt
不再存在,它会增加john
到表-A。
What would be the best way to do this? 最好的方法是什么?
Thanks. 谢谢。
SELECT name FROM Table_A WHERE name NOT IN (SELECT name FROM Table_B)
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