mysql_基础-join

mysql_基础-join、left join 、right join区别

join：select * from  test1 t1  JOIN test2  t2 on  t1.a=t2.a;

left join：select * from  test1 t1 LEFT JOIN  test2  t2 on  t1.a=t2.a;

right join：select * from  test1 t1 RIGHT JOIN  test2  t2 on  t1.a=t2.a;