无论如何根据它的列名将一个值链接到另一个值? 对于例如在下面的非规范化表中,如果state_cd_1是'TX',我需要考虑来自另一个表的state_amt_1列的值,如果state_cd_2也是'TX',则需要将该值添加到state_amt_2。
create table states (state_id int not null auto_increment, state_cd_1 varchar(100), state_cd_2 varchar(100), state_cd_3 varchar(100), state_cd_4 varchar(100), state_cd_5 varchar(100), primary key (state_id));
insert into states values (NULL, 'TX', NULL, NULL, NULL , 'OR');
insert into states values (NULL, 'OR', 'UT', NULL, NULL , NULL);
insert into states values (NULL, 'AZ', 'OR', 'UT', NULL , 'AZ');
create table amount (amt_id int not null auto_increment, state_amt_1 varchar(100), state_amt_2 varchar(100), state_amt_3 varchar(100), state_amt_4 varchar(100), state_amt_5 varchar(100), primary key (amt_id));
insert into amount values (NULL, '100', 900, NULL, NULL , '200');
insert into amount values (NULL, '250', '300', NULL, NULL , NULL);
insert into amount values (NULL, '400', '290', '350', NULL , '450');
(11:34) mysql>select * from states;
+----------+------------+------------+------------+------------+------------+
| state_id | state_cd_1 | state_cd_2 | state_cd_3 | state_cd_4 | state_cd_5 |
+----------+------------+------------+------------+------------+------------+
| 1 | TX | NULL | NULL | NULL | OR |
| 2 | OR | UT | NULL | NULL | NULL |
| 3 | AZ | OR | UT | NULL | AZ |
+----------+------------+------------+------------+------------+------------+
(11:34) mysql>select * from amount;
+--------+-------------+-------------+-------------+-------------+-------------+
| amt_id | state_amt_1 | state_amt_2 | state_amt_3 | state_amt_4 | state_amt_5 |
+--------+-------------+-------------+-------------+-------------+-------------+
| 1 | 100 | 900 | NULL | NULL | 200 |
| 2 | 250 | 300 | NULL | NULL | NULL |
| 3 | 400 | 290 | 350 | NULL | 450 |
+--------+-------------+-------------+-------------+-------------+-------------+
Expected result:
TX 100
OR 740
UT 650
AZ 850
OR
TX OR UT AZ
100 740 650 850
How to calculate:
TX: 100
OR: 200+250+290=740
UT: 300+350=650
AZ: 400+450=850
注意: 国家的名称可能会改变。
答案 0 :(得分:2)
这很难看,但你可以用这样的工会做到这一点:
SELECT st, sum(amt) FROM (
(
SELECT s.state_cd_1 AS st, a.state_amt_1 AS amt
FROM states AS s JOIN amount AS a ON s.state_id = a.amt_id
WHERE s.state_cd_1 IS NOT NULL AND a.state_amt_1 IS NOT NULL
) UNION ALL (
SELECT s.state_cd_2 AS st, a.state_amt_2 AS amt
FROM states AS s JOIN amount AS a ON s.state_id = a.amt_id
WHERE s.state_cd_2 IS NOT NULL AND a.state_amt_2 IS NOT NULL
) UNION ALL (
SELECT s.state_cd_3 AS st, a.state_amt_3 AS amt
FROM states AS s JOIN amount AS a ON s.state_id = a.amt_id
WHERE s.state_cd_3 IS NOT NULL AND a.state_amt_3 IS NOT NULL
) UNION ALL (
SELECT s.state_cd_4 AS st, a.state_amt_4 AS amt
FROM states AS s JOIN amount AS a ON s.state_id = a.amt_id
WHERE s.state_cd_4 IS NOT NULL AND a.state_amt_4 IS NOT NULL
) UNION ALL (
SELECT s.state_cd_5 AS st, a.state_amt_5 AS amt
FROM states AS s JOIN amount AS a ON s.state_id = a.amt_id
WHERE s.state_cd_5 IS NOT NULL AND a.state_amt_5 IS NOT NULL
)) AS joined GROUP BY st;