小编0x6*_*773的帖子

使用两个LEFT JOINs ie

SELECT <some columns>
FROM Table1 AS t1
LEFT JOIN Table2 AS t2 ON <condition1>
LEFT JOIN Table2 AS t3 ON <condition2>

这和AND在 single 中使用一样LEFT JOIN吗？IE

SELECT <some columns>
FROM Table1 AS t1
LEFT JOIN Table2 AS t2 ON <condition1>
AND <condition2>

两者是相同的还是不同的（一般来说）？