[英]MySQL-how to merge multiple rows into multiple columns and one row?
If I have a MySQL table looking something like this: for example 2014000 is a product pen , there are four types abcd with different prices. 如果我有一个看起来像这样的MySQL表:例如2014000是一支产品笔,则有四种类型的abcd价格不同。 and 2014001 is another prodct telephone , also there three types efg with different prices. 2014001是另一款产品电话,也有三种不同价格的efg。 now I want to get the one product one line with names and values. 现在我想让一种产品具有名称和值的一行。
id code name value
1 2014000 A 10
2 2014000 B 9
3 2014000 C 11
4 2014000 D 12
5 2014001 E 100
6 2014001 F 110
7 2014001 G 120
respect result: 尊重结果:
code name1 value1 name2 value2 name3 value3 name4 value4
----------- --------- --------- --------- --------- ----------- --------- --------- ---------
2014000 A 10 B 9 C 11 D 12
2014001 E 100 F 110 G 120 null null
CREATE TABLE T (ID INT, code INT, NAME CHAR(1), VALUE VARCHAR(10)); 创建表T(ID INT,代码INT,NAME CHAR(1),VALUE VARCHAR(10));
INSERT INTO T VALUES(1,2014000,'A','10'), (2,2014000,'B','9'), (3,2014000,'C','11'), (4,2014000,'D','12'), (5,2014001,'E','100'), (6,2014001,'F','110'), (7,2014001,'G','120'); 插入T值(1,2014000,'A','10'),(2,2014000,'B','9'),(3,2014000,'C','11'),(4,2014000 ,'D','12'),(5,2014001,'E','100'),(6,2014001,'F','110'),(7,2014001,'G','120' );
-----the followed only for two rows , if there are more than four rows, how to do it? -----其后仅用于两行,如果有四行以上,该怎么办?
SELECT T1.code, T2.name AS name1, T2.value AS value1, T3.name AS name2, T3.value AS value2 FROM( SELECT code,MIN(ID) AS ID1,CASE COUNT(code) WHEN 1 THEN NULL ELSE MAX(ID) END AS ID2 FROM T GROUP BY code ) T1 LEFT JOIN T T2 ON T1.ID1 = T2.ID LEFT JOIN T T3 ON T1.ID2 = T3.ID
SELECT t.code
, t1.name name1
, t1.value value1
, t2.name name2
, t2.value value2
, t3.name name3
, t3.value value3
, t4.name name4
, t4.value value4
FROM ( SELECT code
, group_concat(ID) ids
FROM T
GROUP BY code
) t
LEFT JOIN T t1
ON find_in_set(t1.ID,t.ids)=1
LEFT JOIN T t2
ON find_in_set(t2.ID,t.ids)=2
LEFT JOIN T t3
ON find_in_set(t3.ID,t.ids)=3
LEFT JOIN T t4
ON find_in_set(t4.ID,t.ids)=4
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