需要帮助的SQL查询联接 [英] Need help for sql query join

问题描述

大家好

Hi all

SELECT FK_PROJECT_ID FROM PROJECT_LEAD_MAPPING PLM WHERE PLM.LEADER_ID = 1 AND PLM.IS_ACTIVE = 1
UNION
SELECT FK_PROJECT_ID FROM TESTCAT_PROJECT_MAPPING TPM WHERE TPM.FK_TESTCAT_ID = 1 AND TPM.IS_ACTIVE = 1
UNION
SELECT PROJECT_ID FROM PROJECT_MEMBER PM 
WHERE (PM.START_DATE <= '2012-4-17' AND PM.END_DATE > '2012-4-17') AND PM.MEMBER_ID = 1

如何使用join编写上述查询.

在此先感谢

How to write the above query using join.

Thanks in advance

推荐答案

从您给出的查询中，我猜您可以将列"LEADER_ID，FK_TESTCAT_ID，MEMBER_ID"用于连接条件，因为您将所有这些列值都与"1"进行了比较.因此，通过对此进行猜测，我在下面的查询中使用了内部Join.试试吧.

Hi,
From the query that you have given, I guess that you can use columns "LEADER_ID, FK_TESTCAT_ID , MEMBER_ID" for the joining conditions, because you are comparing all these column values to "1". So, by guesing this I am giving you this below query which uses inner Join. Try it out.

SELECT FROM PLM.FK_PROJECT_ID, TPM.FK_PROJECT_ID,PM.PROJECT_ID FROM   PROJECT_LEAD_MAPPING PLM 
INNER JOIN 
TESTCAT_PROJECT_MAPPING TPM ON PLM.LEADER_ID = TPM.FK_TESTCAT_ID 
INNER JOIN
PROJECT_MEMBER PM ON PM.MEMBER_ID = PLM.LEADER_ID
WHERE PLM.IS_ACTIVE = 1 AND TPM.IS_ACTIVE = 1 AND (PM.START_DATE <= '2012-4-17' AND PM.END_DATE > '2012-4-17')

这将为您提供按列的值.

希望对您有所帮助.

This will give you values in column wise.

hope it helps.

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