我如何在DB2中透视表?

时间:2012-11-27 07:13:55

标签: sql db2

我在下面有表A,其中对于每个唯一ID,有三个代码具有某些值。

 ID    Code    Value
---------------------
 11       1       x
 11       2       y
 11       3       z
 12       1       p
 12       2       q
 12       3       r
 13       1       l
 13       2       m
 13       3       n

我有第二张表格B,格式如下:

Id   Code1_Val   Code2_Val    Code3_Val

这里每个唯一ID只有一行。我想从第一个表A中为第一个表中的每个id填充第二个表B.

对于上面的第一个表A,第二个表B应该表示为:

Id   Code1_Val   Code2_Val    Code3_Val
---------------------------------------------
11       x          y             z
12       p          q             r
13       l          m             n

如何在单个SQL查询中实现此目的?

7 个答案:

答案 0 :(得分:6)

   select Id,                                              
      max(case when Code = '1' then Value end) as Code1_Val,  
      max(case when Code = '2' then Value end) as Code2_Val,  
      max(case when Code = '3' then Value end) as Code3_Val   
      from TABLEA                                     
      group by Id                                            

答案 1 :(得分:2)

如果您的版本没有DECODE(),您也可以使用:

INSERT INTO B (id, code1_val, code2_val, code3_val)  
WITH Ids (id) as (SELECT DISTINCT id
                  FROM A) -- Only to construct list of ids

SELECT Ids.id, a1.value, a2.value, a3.value
FROM Ids -- or substitute the actual id table
JOIN A a1
     ON a1.id = ids.id
        AND a1.code = 1
JOIN A a2
     ON a2.id = ids.id
        AND a2.code = 2
JOIN A a3
     ON a3.id = ids.id
        AND a3.code = 3

(适用于我的V6R1 DB2实例,并有一个SQL Fiddle Example)。

答案 2 :(得分:1)

SELECT Id,
max(DECODE(Code, 1, Value)) AS Code1_Val,
max(DECODE(Code, 2, Value)) AS Code2_Val,
max(DECODE(Code, 3, Value)) AS Code3_Val
FROM A
group by Id

答案 3 :(得分:0)

这是SQLFiddle example

insert into B (ID,Code1_Val,Code2_Val,Code3_Val)
select Id, max(V1),max(V2),max(V3) from
(
select ID,Value V1,'' V2,'' V3 from A where Code=1
union all
select ID,'' V1, Value V2,'' V3 from A where Code=2
union all
select ID,'' V1, '' V2,Value V3 from A where Code=3
) AG
group by ID

答案 4 :(得分:0)

这是SQL查询:

insert into pivot_insert_table(id,code1_val,code2_val, code3_val) 
select * from (select id,code,value from pivot_table)
pivot(max(value) for code in (1,2,3)) order by id ;

答案 5 :(得分:0)

MKIMAGEOUTPUT_SPL = SPL.log

答案 6 :(得分:-1)

您想要透视数据。由于DB2没有pivot函数,你可以使用Decode(基本上是一个case语句。)

语法应为:

SELECT Id,
   DECODE(Code, 1, Value) AS Code1_Val,
   DECODE(Code, 2, Value) AS Code2_Val,
   DECODE(Code, 3, Value) AS Code3_Val
FROM A