数据准备

 

 SELECT t1.id,t1.name,t2.local FROM t1 LEFT JOIN t2 ON t1.id=t2.id;
执行结果

 
SELECT t1.id,t1.name,t2.local FROM t1 LEFT JOIN t2 ON t1.id=t2.id and t2.local='beijing';

 SELECT t1.id,t1.name,t2.local FROM t1 LEFT JOIN t2 ON t1.id=t2.id where t2.local='beijing';

 SELECT t1.id,t1.name,t2.local FROM t1 LEFT JOIN t2 ON t1.id=t2.id and t1.name='a11';

SELECT t1.id,t1.name,t2.local FROM t1 LEFT JOIN t2 ON t1.id=t2.id and t1.name='a33';

 

SELECT t1.id,t1.name,t2.local FROM t1 LEFT JOIN t2 ON t1.id=t2.id where t1.name='a33';

SELECT t1.id,t1.name,t2.local FROM t1 LEFT JOIN t2 ON t1.id=t2.id where t1.name='a22';