使用具有多连接的FROM子句更新语句 [英] Update statement with FROM clause with multi joins

问题描述

sql Update语句如何工作，同时使用带有多个连接的FROM子句[在这种情况下WHERE子句如何工作]？，



也是必要的要更新的表必须在FROM子句中吗？



请解释

解决方案

更新在你告诉它的桌子上工作。例如：

 更新 table1 
  SET  Field1 = ' ' 

将更新table1。



from子句将限制更新内容。除非您尝试加入其他表，否则不需要From子句。

还需要更新的表必须在FROM子句中吗？

how the sql Update statement work , while using FROM Clause with multiple joins[also in this situation how the WHERE clause work] ?,

also is it necessary that the table which is getting updated has to be in FROM clause ?

kindly explain

解决方案

Update works on the table you tell it to. For example:

UPDATE table1 
SET Field1 = ''

will update table1.

The from clause will limit what gets updated. You don't need a From clause unless you are trying to join in other tables.

also is it necessary that the table which is getting updated has to be in FROM clause ?

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