left join or

right join在使用时的区别是什么？

在使用left join时，左表（即左侧的表格）的记录数与left join后的结果记录数相同，而使用right join时，右表（即右侧的表格）的记录数与right join后的结果记录数相同。换句话说，left join会返回左表的全部记录，而right join会返回右表的全部记录。这是因为left join以左表为准，将左表的记录与右表进行连接，而right join以右表为准，将右表的记录与左表进行连接。所以left join和right join是等价的，只是连接顺序不同。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
#### 引用[.reference_title]
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