mysql 全连接查询合并字段
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mysql 全连接查询合并字段
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1、創建兩張表
表t1:
| id | name |
| 1 | a1 |
| 3 | a3 |
表t2:?
| id | name |
| 1 | b1 |
| 2 | b2 |
| 5 | b5 |
聯合查詢合并字段:?
| a1?? ?? ? | b1? | 1 |
| 0 | b2 | 2 |
| a3 | 0 | 3 |
| 0 | b5 | 5 |
sql如下:
SELECT IFNULL(t3.name,0) as B, IFNULL(t3.name1,0) 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.idUNIONSELECT 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?
?
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