SELECT t1.*,t2.*,t3.* FROM t1 LEFT OUTER JOIN t2 ON t1.col=t2.col LEFT OUTER JOIN t3 ON t1.col=t3.col
如果t2要和t3和t4关联呢?
SELECT t1.*,t2.*,t3.*,t4.* FROM t1 LEFT OUTER JOIN t2 ON t1.col=t2.col LEFT OUTER JOIN t3 ON t1.col=t3.col LEFT OUTER JOIN t2 ON t2.col=t3.col LEFT OUTER JOIN t4 ON t2.col=t4.col 这样写吗?
如果t2要和t3和t4关联呢?
LEFT OUTER JOIN t2 ON t1.col=t2.col
LEFT OUTER JOIN t3 ON t1.col=t3.col
LEFT OUTER JOIN t2 ON t2.col=t3.col
LEFT OUTER JOIN t4 ON t2.col=t4.col
这样写吗?