1、创建两张表 t1如下： id name 1 a1 3 a3 t2如下： id name 1 b1 2 b2 5 b5 联合查询合并字段： sql语句： SELECT t3.`name` AS B, t3.`name1` AS C ,COALESCE(t3.id2,t3.id1) AS myId FROM (SELECT t1.id as id2 ,t1.`name` as name,t2.id as id1 ,t2.`na
1、创建两张表
t1如下：
| id | name |
| 1 | a1 |
| 3 | a3 |
t2如下：
| id | name |
| 1 | b1 |
| 2 | b2 |
| 5 | b5 |
联合查询合并字段：
sql语句：
SELECT t3.`name` AS B, t3.`name1` AS C ,COALESCE(t3.id2,t3.id1) AS myId
FROM (SELECT t1.id as id2 ,t1.`name` as name,t2.id as id1 ,t2.`name` as name1 FROM t1 LEFT JOIN t2 on t1.id=t2.idUNION SELECT t1.id as id2 ,t1.`name` as name,t2.id as id1 ,t2.`name` as name1 from t1 RIGHT JOIN t2 on t1.id=t2.id) as t3 GROUP BY myId;
查询结果：
| B | C | myID |
| a1 | b1 | 1 |
| b2 | 2 | |
| a3 | 3 | |
| b5 | 5 | |
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