DB2中的动态透视SQL查询 [英] dynamic pivot SQL Query in DB2
本文介绍了DB2中的动态透视SQL查询的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我在DB2中有类似下面的表,其中这3列都是VARCHAR数据类型
DATE_F FILE_NM ROW_ID COLUMN_NM COLUMN_VAL
20200131 ABC.TXT 1 ABC_COL1 123
20200131 ABC.TXT 1 ABC_COL2 XYZ
20201231 ABC.TXT 2 ABC_COL1 456
20201231 ABC.TXT 2 ABC_COL2 XY1
20200630 XYZ.TXT 1 XYZ_COL1 PQR
20200630 XYZ.TXT 1 XYZ_COL2 567
20200630 XYZ.TXT 1 XYZ_COL3 MNO
我需要一个动态透视查询,当FILE_NM筛选器用作ABC.TXT
时,它应该以行格式选择ABC_COL1和ABC_COL2的值当FILE_NM筛选器用作XYZ.TXT时,同一查询应以行格式选择XYZ_COL1、XYZ_COL2和XYZ_COL3的值
当FILE_NM=ABC.TXT时输出应如下所示
DATE_F ROW_ID ABC_COL1 ABC_COL2
20200131 1 123 XYZ
20201231 2 456 XY1
当FILE_NM=XYZ.TXT时,输出应如下所示
DATE_F ROW_ID XYZ_COL1 XYZ_COL2 XYZ_COL3
20200630 1 PQR 567 MNO
因此,一个查询将能够提取数据。在这种情况下,是否有任何函数或等效函数可以执行此任务?
推荐答案
您可以尝试使用以下泛型存储过程进行透视。
--#SET TERMINATOR @
create or replace procedure pivot
(
in sel_stmt varchar(4000)
, in row_cols varchar(200)
, in col_col varchar(128)
, in agg_col varchar(128)
, in agg_fn varchar(10)
, in tmp_tbl varchar(128)
, in null_ind varchar(10)
, out rc int
, out msg varchar(128)
, out stmt varchar(4000)
)
LANGUAGE SQL
DYNAMIC RESULT sets 1
BEGIN
declare QUOT1 char(1) default '''';
declare QUOT2 char(1) default '"';
declare SQLCODE int default 0;
declare SQLTYPE_ID int;
declare SQLTYPE varchar(128);
declare SQLLENGTH int;
declare SQLSCALE int;
declare SQLNAME_DATA varchar(128);
declare SQLTYPEF varchar(128);
declare col_val varchar(4000);
declare apo varchar(1);
declare l1 RESULT_set_LOCATOR VARYING;
declare c2 cursor for s2;
declare c_out cursor with return for s_out;
declare EXIT HANDLER FOR SQLEXCEPTION
BEGIN
GET DIAGNOSTICS EXCEPTION 1 MSG = MESSAGE_TEXT;
set RC = SQLCODE;
END;
set col_col=upper(col_col);
set agg_col=upper(agg_col);
-- insert result of select statement into temp table
set stmt = 'describe '||sel_stmt;
call SYSPROC.ADMIN_CMD(stmt);
set stmt = '';
associate result set locator (l1)
with procedure SYSPROC.ADMIN_CMD;
allocate c1 cursor for result set l1;
--open c1;
fetch c1 into SQLTYPE_ID, SQLTYPE, SQLLENGTH, SQLSCALE, SQLNAME_DATA;
while (SQLCODE!=100) do
set SQLTYPEF = SQLTYPE
||case
when SQLTYPE IN ('DECIMAL', 'DECFLOAT', 'CHARACTER', 'VARCHAR') then
'('||RTRIM(CHAR(SQLLENGTH))
||case when SQLTYPE='DECIMAL' then ','||RTRIM(CHAR(SQLSCALE)) else '' end
||')'
else ''
end;
if (col_col=SQLNAME_DATA) then
set apo =
case
when SQLTYPE in ('DECIMAL', 'DECFLOAT', 'INTEGER', 'SMALLINT', 'BIGINT', 'REAL', 'DOUBLE') then ''
else QUOT1
end;
end if;
set stmt = stmt||', '||SQLNAME_DATA||' '||SQLTYPEF;
fetch c1 into SQLTYPE_ID, SQLTYPE, SQLLENGTH, SQLSCALE, SQLNAME_DATA;
end while;
close c1;
set stmt =
'declare global temporary table '||tmp_tbl||'('||substr(stmt, 3)
||') with replace on commit preserve rows not logged';
execute immediate stmt;
set stmt = 'insert into '||tmp_tbl||' '||sel_stmt;
execute immediate stmt;
-- construct select statement
set stmt = 'select distinct rtrim(char('||col_col||')) from '||tmp_tbl||' order by 1';
prepare s2 from stmt;
set stmt='';
open c2;
fetch c2 into col_val;
while (SQLCODE!=100) do
set stmt =
stmt||', '||agg_fn||'('
||'case when '||col_col||' '
||case when col_val is null then 'IS NULL' else ('='||apo||replace(col_val, QUOT1, QUOT1||QUOT1)||apo) end
||' then '||agg_col||' end) as '||QUOT2||coalesce(replace(col_val, QUOT2, QUOT2||QUOT2), null_ind)||QUOT2;
fetch c2 into col_val;
end while;
close c2;
-- add to the select statement groups
set row_cols = nullif(row_cols, '');
set stmt =
'select '||case when row_cols is not null then row_cols||',' else coalesce(row_cols, '') end
||substr(stmt, 2)||' from '||tmp_tbl||' '
||case when row_cols is not null then ('group by '||row_cols||' order by '||row_cols) else '' end;
-- execute this statement
prepare s_out from stmt;
open c_out;
END@
参数说明:
参数 | 设计 |
---|---|
sel_stmt | 用于生成源数据的任何有效SELECT语句 |
行数 | 最后一条语句的GROUP BY中使用的列名的逗号分隔列表 |
列_列 | 要透视的列名 |
AGG_COOL | 要聚合的列名 |
agg_fn | 参数中列名的任何有效的DB2聚合函数 |
tmp_tbl | 中间结果的DGTT名称 |
NULL_ind | 空指示符 |
rc | 返回代码(OUT) |
消息 | 消息文本(Out) |
stmt | 最终选择已生成(输出) |
简介:
将创建传入tmp_tbl
的DGTT,并使用传入的sel_stmt
SELECT语句的结果进行填充。row_cols
、col_col
、agg_col
中指定的所有列名都必须在此语句的选择列表中。
此DGTT的最后一条SELECT语句是使用以下规则动态生成的:
- 对于
col_col
传入的列名中每个不同的值Vx
,生成一个额外的列表达式,如下所示:, <agg_fn> (case when <col_col> = Vx then <agg_col> end) as "Vx"
(, <agg_fn> (case when <col_col> IS NULL then <agg_col> end) as "<null_ind>"
用于Vx
为空),其中<parameter>
表示该参数传递的字符串值。 row_cols
列列表用于GROUP BY
,如果它不为空。
用于您的案例:
DECLARE GLOBAL TEMPORARY TABLE SESSION.MYTAB
(DATE_F, FILE_NM, ROW_ID, COLUMN_NM, COLUMN_VAL)
AS
(
VALUES
('20200131', 'ABC.TXT', 1, 'ABC_COL1', '123')
, ('20200131', 'ABC.TXT', 1, 'ABC_COL2', 'XYZ')
, ('20201231', 'ABC.TXT', 2, 'ABC_COL1', '456')
, ('20201231', 'ABC.TXT', 2, 'ABC_COL2', 'XY1')
, ('20200630', 'XYZ.TXT', 1, 'XYZ_COL1', 'PQR')
, ('20200630', 'XYZ.TXT', 1, 'XYZ_COL2', '567')
, ('20200630', 'XYZ.TXT', 1, 'XYZ_COL3', 'MNO')
) WITH DATA WITH REPLACE ON COMMIT PRESERVE ROWS NOT LOGGED;
第一次调用:
call pivot
(
'select * from session.mytab where file_nm = ''ABC.TXT'''
, 'DATE_F, ROW_ID'
, 'COLUMN_NM'
, 'COLUMN_VAL'
, 'max'
, 'session.tab1'
, '-'
, ?, ?, ?
);
DATE_F | ROW_ID | abc_col1 | ABC_COL2 |
---|---|---|---|
20200131 | 1 | 123 | XYZ |
20201231 | 2 | 456 | XY1 |
第二次呼叫:
call pivot
(
'select * from session.mytab where file_nm = ''XYZ.TXT'''
, 'DATE_F, ROW_ID'
, 'COLUMN_NM'
, 'COLUMN_VAL'
, 'max'
, 'session.tab1'
, '-'
, ?, ?, ?
);
DATE_F | ROW_ID | XYZ_COL1 | XYZ_COL2 | XYZ_COL3 |
---|---|---|---|---|
20200630 | 1 | PQR | 567 | MNO |
这篇关于DB2中的动态透视SQL查询的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文