Db2 Pivot 函数 - 获取下一条语句

Question

在https://www.itjungle.com/2015/04/21/fhg042115-story01/ 下可以找到一篇关于如何编写通用 Db2 枢轴方法的好文章。

执行以下代码（注意 'end #' 而不是 'end ;'）：

SET SCHEMA = TESTSCHEMA;

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' ) ;

产生错误信息：

DB21034E  The command was processed as an SQL statement because it was
not a valid Command Line Processor command.  During SQL processing it
returned:
SQL0104N  An unexpected token "FROM" was found following "    FETCH
NEXT".
Expected tokens may include:  ".".  LINE NUMBER=50.  SQLSTATE=42601

• 该过程似乎是为可能在 iSeries 上的旧 Db2 版本编程的
• 关于当前的 LUW 版本（10.5、11.1），代码 sn-p 中“fetch next”的语法乍一看似乎是正确的：https://www.ibm.com/support/knowledgecenter/en/SSEPGG_10.5.0/com.ibm.db2.luw.sql.ref.doc/doc/r0000954.html
• 在 Db2 Big SQL 4.2（“DB2 v11.1.0.0”、“s160705”、“BSQL160705AMD64”和 Fix Pack “0”）上测试

有什么建议吗？

Answer 1

对于 Db2-LUW v11.1 及更高版本，要编译 sproc，您可以进行下面列出的更改。这只是为了获得成功的编译。我没有检查功能。

• 删除（或注释掉）PROGRAM TYPE SUB

• 删除（或注释掉）并发访问分辨率默认值

• 将 FETCH NEXT FROM 更改为 FETCH（在两个地方），或使用 FETCH FROM

• 删除（或注释掉）LABEL ON ROUTINE 语句

• 删除（或注释掉）COMMENT ON PARAMETER ROUTINE 语句