以如下leftjoin查询语句为范例：select*fromt1leftjoint2ont1.c=t2.a;以下初始化数据：1DROPTABLEIFEXISTS`t1`;2CREATETABLE`t1`(3`a`intDEFAULTNULL,4`b`varchar(20)DEFAULTNULL5)6INSERTINTO`t1`VALUES(1,'a');7INSERTINTO`t1`VALUES(1,'b');8INSERTINTO`t1`VALUES(4,'a');9INSERTINTO`t1`VALUES(5,'a');1011DROPTABLEIFEXISTS`t2`;12CREATET

以如下leftjoin查询语句为范例：select*fromt1leftjoint2ont1.c=t2.a;以下初始化数据：1DROPTABLEIFEXISTS`t1`;2CREATETABLE`t1`(3`a`intDEFAULTNULL,4`b`varchar(20)DEFAULTNULL5)6INSERTINTO`t1`VALUES(1,'a');7INSERTINTO`t1`VALUES(1,'b');8INSERTINTO`t1`VALUES(4,'a');9INSERTINTO`t1`VALUES(5,'a');1011DROPTABLEIFEXISTS`t2`;12CREATET