如何使用链接到第三个表的条件连接两个表

xj3cbfub  于 2021-06-15  发布在  Mysql
关注(0)|答案(1)|浏览(296)

我有三张table

  1. Table1 : ID, Description
  2. Table2 : ID, FirstName, LastName
  3. Table3 : FirstName, LastName, Flag

我想用一个链接到第三个表的条件左联接table1和table2。

  1. Result Table: ID, Description, FullName (FirstName + LastName)
  2. (Condition: only the names that have flag set to true in table3 can be used in the resultant table)

如何完成以下任务?先谢谢你。

dbf7pr2w

dbf7pr2w1#

  1. SELECT t1.ID, t1.Description, t2.FirstName + ' ' + t2.LastName as FullName
  2. FROM Table1 t1
  3. JOIN Table2 t2 ON t1.ID = t2.ID
  4. JOIN Table3 t3 ON t2.FirstName=t3.FirstName AND t2.LastName=t3.LastName
  5. WHERE t3.Flag=1

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