技術標籤：mysqlmysql

Mysql刷題筆記

CREATE TABLE T0120
(
  ID int,
	NAME varchar(22),
	MON int,
	STATE varchar(21),
	AMOUNT int
);

INSERT INTO T0120 VALUES(1,'張三',201901,'A',9000);
INSERT INTO T0120 VALUES(2,'張三',201901,'B',9000);
INSERT INTO T0120 VALUES(3,'張三',201901,'E',9000);
INSERT INTO T0120 VALUES(4,'李四',201902,'A',1800);
 

INSERT INTO T0120 VALUES(5,'李四',201902,'C',1800);
INSERT INTO T0120 VALUES(6,'王五',201902,'C',30000);
INSERT INTO T0120 VALUES(7,'王五',201902,'F',30000);

T0120
+------+--------+--------+-------+--------+
| ID   | NAME   | MON    | STATE | AMOUNT |
+------+--------+--------+-------+--------+
|    1 | 張三   | 201901 | A     |   9000
 
 |
|    2 | 張三   | 201901 | B     |   9000 |
|    3 | 張三   | 201901 | E     |   9000 |
|    4 | 李四   | 201902 | A     |   1800 |
|    5 | 李四   | 201902 | C     |   1800 |
|    6 | 王五   | 201902 | C     |  30000 |
|    7 | 王五   | 201902 | F     |  30000 |
+------+--------+--------+-------+--------+

結果
+------+--------+--------+-------+--------+
 

| ID   | NAME   | MON    | STATE | AMOUNT |
+------+--------+--------+-------+--------+
|    1 | 張三   | 201901 | A     |   3000 |
|    2 | 張三   | 201901 | B     |   3000 |
|    3 | 張三   | 201901 | E     |   3000 |
|    4 | 李四   | 201902 | A     |    900 |
|    5 | 李四   | 201902 | C     |    900 |
|    6 | 王五   | 201902 | C     |  15000 |
|    7 | 王五   | 201902 | F     |  15000 |
+------+--------+--------+-------+--------+

SELECT ID,t.NAME,MON,STATE,ROUND(AMOUNT/t.C,0) AS AMOUNT
FROM T0120 LEFT JOIN
(
  SELECT NAME,COUNT(*) AS C
  FROM T0120
  GROUP BY NAME,MON
)t
ON T0120.NAME = t.NAME

SELECT ID,NAME,MON,STATE,ROUND(AMOUNT/
    (SELECT COUNT(1) FROM T0120 b WHERE a.MON = b.MON AND a.NAME = b.NAME)) AS AMOUNT
FROM T0120 a