Mysql 如何将这些行合并到同一表中的一条记录中
表X中的原始数据Mysql 如何将这些行合并到同一表中的一条记录中,mysql,sql,select,group-by,pivot,Mysql,Sql,Select,Group By,Pivot,表X中的原始数据 Date # Method # Count # ====================================== 2012-08-24 # A # 44 # 2012-08-24 # B # 5 # 2012-08-24 # D # 1 # *p/s共有8种方法,即a、b
Date # Method # Count #
======================================
2012-08-24 # A # 44 #
2012-08-24 # B # 5 #
2012-08-24 # D # 1 #
*p/s共有8种方法,即a、b、c、d、e、f、g、h
我想显示的内容如下:
Date # A # B # C # D # E # F # G # H #
2012-08-24 # 44 # 5 # 0 # 1 # 0 # 0 # 0 # 0 #
试试这个:
SELECT A.Date,
SUM(CASE WHEN A.Method = 'A' THEN A.Count ELSE 0 END) AS 'A',
SUM(CASE WHEN A.Method = 'B' THEN A.Count ELSE 0 END) AS 'B',
SUM(CASE WHEN A.Method = 'C' THEN A.Count ELSE 0 END) AS 'C',
SUM(CASE WHEN A.Method = 'D' THEN A.Count ELSE 0 END) AS 'D',
SUM(CASE WHEN A.Method = 'E' THEN A.Count ELSE 0 END) AS 'E',
SUM(CASE WHEN A.Method = 'F' THEN A.Count ELSE 0 END) AS 'F',
SUM(CASE WHEN A.Method = 'G' THEN A.Count ELSE 0 END) AS 'G',
SUM(CASE WHEN A.Method = 'H' THEN A.Count ELSE 0 END) AS 'H'
FROM tableA A
GROUP BY A.Date
您可以交替使用IF
SELECT
A.Date,
IF(A.Methos = 'A',A.Count,0) AS 'A',
IF(A.Methos = 'B',A.Count,0) AS 'B',
IF(A.Methos = 'C',A.Count,0) AS 'C',
IF(A.Methos = 'D',A.Count,0) AS 'D',
IF(A.Methos = 'E',A.Count,0) AS 'E',
IF(A.Methos = 'F',A.Count,0) AS 'F',
IF(A.Methos = 'G',A.Count,0) AS 'G',
IF(A.Methos = 'H',A.Count,0) AS 'H',
FROM tableA A
GROUP BY A.Date
这叫做支点。有很多答案,所以,做一个搜索。