[英]Pivoting DB2 Data - where number of columns and and rows are not fixed
我在这里看到了一些类似的Q / A,但是我所看到的情况是“按季度销售的年度”变化的变化,因此使用了DECODE,有4个类别。
就我而言,我事先不知道枢轴将有多少行或多少列。
| Pay | Age | Value |
|-----|-----|-------|
| 1 | 1 | 10 |
| 1 | 2 | 20 |
| 1 | 3 | 30 |
| 2 | 1 | 90 |
| 2 | 2 | 80 |
| 2 | 3 | 70 |
我们希望结果集为
PAYGROUP Millennials GenX Boomers
1 10 20 30
2 90 80 70
使用PIVOT
语句很容易,即
Transform Max(VALUE) AS V
SELECT PAYGROUP
FROM table
GROUP BY PAYGROUP
PIVOT AGEGROUP;
但是我的DB2没有PIVOT
功能。
薪酬组和年龄组的数量可能因案例而异,例如,数据可以针对不同案例具有不同的薪酬和年龄组数量。
可以完成此操作,但只能在SQL过程或其他HLL中完成。
您使用一个SQL语句找出了多少个不同的值,然后使用这些值构建了一个动态SQL语句。
如果您将DB2平台和版本添加到问题中,则可以为您提供一个示例。
这是一个纯SQL过程(最初适用于IBM i的DB2,但应适用于LUW),可在以下位置找到: https : //www.itjungle.com/2015/04/21/fhg042115-story01/
SET SCHEMA = WHER_YOU_WANT_IT;
CREATE PROCEDURE DO_PIVOT
(IN FOR_SCHEMA CHARACTER (10) ,
IN FOR_TABLE CHARACTER (10) ,
IN PIVOT_COLUMN VARCHAR (250) ,
IN VALUE_COLUMN VARCHAR (250) ,
IN AGG_FUNCTION VARCHAR (5) DEFAULT 'SUM' ,
IN GROUP_COLUMN VARCHAR (250) DEFAULT NULL )
LANGUAGE SQL
MODIFIES SQL DATA
PROGRAM TYPE SUB
CONCURRENT ACCESS RESOLUTION DEFAULT
DYNAMIC RESULT SETS 1
OLD SAVEPOINT LEVEL COMMIT ON RETURN NO
BEGIN
DECLARE SQLCODE INTEGER DEFAULT 0 ;
DECLARE SQL_STATEMENT VARCHAR ( 5000 ) ;
DECLARE PIVOT_VALUE VARCHAR ( 20 ) ;
DECLARE PAD CHAR ( 2 ) DEFAULT ' ' ;
DECLARE C1 CURSOR FOR D1 ;
DECLARE C2 CURSOR WITH RETURN FOR D2 ;
SET SCHEMA = FOR_SCHEMA ;
-- Get the list of values available for the pivot column
-- Each value will be a column in the return set
SET SQL_STATEMENT = 'select distinct '
|| PIVOT_COLUMN
|| ' from '
|| FOR_TABLE
|| ' order by 1' ;
PREPARE D1 FROM SQL_STATEMENT ;
OPEN C1 ;
-- Construct a dynamic select statement for the pivot
SET SQL_STATEMENT = 'select ' ;
-- If requested, add the Group By Column
-- to the select clause
IF GROUP_COLUMN IS NOT NULL THEN
SET SQL_STATEMENT = SQL_STATEMENT || GROUP_COLUMN ;
SET PAD = ', ' ;
END IF ;
-- For each possible value for the Pivot Column,
-- add a case statement to perform the requested
-- aggregate function on the Value Column
FETCH NEXT FROM C1 INTO PIVOT_VALUE ;
WHILE ( SQLCODE >= 0 AND SQLCODE <> 100 ) DO
SET SQL_STATEMENT = SQL_STATEMENT
|| PAD
|| AGG_FUNCTION
|| '(CASE WHEN '
|| PIVOT_COLUMN
|| ' = '''
|| PIVOT_VALUE
|| ''' THEN '
|| VALUE_COLUMN
|| ' END) AS '
|| PIVOT_VALUE ;
SET PAD = ', ' ;
FETCH NEXT FROM C1 INTO PIVOT_VALUE ;
END WHILE ;
CLOSE C1 ;
-- Specify the table to select from
SET SQL_STATEMENT = SQL_STATEMENT
|| ' from '
|| FOR_TABLE ;
-- If requested, add the Group By Column
-- to the select clause
IF GROUP_COLUMN IS NOT NULL THEN
SET SQL_STATEMENT = SQL_STATEMENT
|| ' group by '
|| GROUP_COLUMN
|| ' order by '
|| GROUP_COLUMN;
END IF ;
PREPARE D2 FROM SQL_STATEMENT ;
OPEN C2 ;
END ;
LABEL ON ROUTINE DO_PIVOT
( CHAR(), CHAR(), VARCHAR(), VARCHAR(), VARCHAR(), VARCHAR() )
IS 'Perform a General Purpose Pivot';
COMMENT ON PARAMETER ROUTINE DO_PIVOT
( CHAR(), CHAR(), VARCHAR(), VARCHAR(), VARCHAR(), VARCHAR() )
(FOR_SCHEMA IS 'Schema for Table' ,
FOR_TABLE IS 'For Table' ,
PIVOT_COLUMN IS 'Name of Column to be Pivoted' ,
VALUE_COLUMN IS 'Column to be Aggregated for Pivot' ,
AGG_FUNCTION IS 'Use Aggregate Function' ,
GROUP_COLUMN IS 'Group on Column' ) ;
我想您也可以使用XML函数来旋转数据...但是我还没有找到一个很好的例子
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.