select t1.name,ifnull(t2.name, """""") as name from t1 left join t2 on t1.name=t2.name; +------+------+ | name | name | +------+------+ | a | "" | | b | b | | c | c | | d | d | +------+------+ 4 rows in set (0.00 sec)
SELECT A.*,IFNULL(B.`name`,'没有值',B.`name`) FROM A LEFT JOIN B ON A.`name`=B.`name`
select 表A.name,ifnull(表B.name,'没有值' ) as name from t1 left join t2 on 表A.name=表B.name;
SELECT A.*,IFNULL(B.`name`,'没有值') FROM A LEFT JOIN B ON A.`name`=B.`name`
select A.name,case when b.name is null then '没有值' else b.name end from A left join B on A.name = B.name where A.name=B.name
select a.name,b.name from a left join b on a.name=b.name
+------+------+
| name | name |
+------+------+
| a | "" |
| b | b |
| c | c |
| d | d |
+------+------+
4 rows in set (0.00 sec)
from A left join B on A.name = B.name
where A.name=B.name
from a left join b on a.name=b.name