SQL oracle获取一行中某一列的值

Question

我有两个表。 第一个'table_fields'

Type Name Label 
ORG  text1 organisation 
ORG  text2 location 
PERS text1 manager 
PERS text2 gender 
PERS text3 age 

第二个“table_data”

Type ID  text1 text2  text3 text4 
ORG  Sven HR  Brussels   
PERS Ludo theo male  43 
ORG  Sara MR  Barcelona 

我尝试做的是像有两个额外的列table_Fields一个表，代表我TABLE_DATA的ID和值table_fields中特定名称的特定列。 我的结果应该是这样的：

Type Name Label   ID_table_data VALUE 
ORG  text1 organisation Sven   HR 
ORG  text2 location  Sven   Brussels 
PERS text1 manager   Ludo   theo 
PERS text2 gender   Ludo   male 
PERS text3 age    Ludo   43 
ORG  text1 organisation Sara   MR 
ORG  text2 location  Sara   Barcelona 

我不知道这样的事情是可能的SQL甲骨文

Answer 1

UNPIVOT使用：

SQL Fiddle

的Oracle 11g R2架构设置：

CREATE TABLE table_fields (Type, Name, Label) AS 
SELECT 'ORG',  'text1', 'organisation' FROM DUAL UNION ALL 
SELECT 'ORG',  'text2', 'location' FROM DUAL UNION ALL 
SELECT 'PERS', 'text1', 'manager' FROM DUAL UNION ALL 
SELECT 'PERS', 'text2', 'gender' FROM DUAL UNION ALL 
SELECT 'PERS', 'text3', 'age' FROM DUAL; 

CREATE TABLE table_data (Type, ID, text1, text2, text3, text4) AS 
SELECT 'ORG', 'Sven', 'HR', 'Brussels', NULL, CAST(NULL AS VARCHAR2(20)) FROM DUAL UNION ALL 
SELECT 'PERS', 'Ludo', 'theo', 'male',  '43', NULL FROM DUAL UNION ALL 
SELECT 'ORG', 'Sara', 'MR', 'Barcelona', NULL, NULL FROM DUAL; 

查询1：

SELECT f.*, 
     d.id, 
     d.value 
FROM table_data 
     UNPIVOT (value FOR name IN (
      text1 AS 'text1', 
      text2 AS 'text2', 
      text3 AS 'text3', 
      text4 AS 'text4' 
     )) d 
     INNER JOIN table_fields f 
     ON (f.type = d.type AND f.name = d.name) 

Results：

| TYPE | NAME |  LABEL | ID |  VALUE | 
|------|-------|--------------|------|-----------| 
| ORG | text1 | organisation | Sven |  HR | 
| ORG | text2 |  location | Sven | Brussels | 
| PERS | text1 |  manager | Ludo |  theo | 
| PERS | text2 |  gender | Ludo |  male | 
| PERS | text3 |   age | Ludo |  43 | 
| ORG | text1 | organisation | Sara |  MR | 
| ORG | text2 |  location | Sara | Barcelona | 

Answer 2

你正在寻找一个INNER JOIN像：

SELECT t2.* 
     ,t2.ID AS ID_table_data 
     ,CASE 
      WHEN t2.NAME = 'text1' 
       THEN d.text1 
      WHEN t2.NAME = 'text2 ' 
       THEN d.text2 
      WHEN t2.NAME = 'text3 ' 
       THEN d.text3 
      END As VALUE 
FROM table_fields t1 INNER JOIN table_data t2 ON t1.Type = t2.Type 

编辑： 根据我在开始时并未意识到的MT0评论，我编辑了添加CASE语句以匹配预期结果

Answer 3

如果你不能够使用UNPIVOT，这是由MT0建议，因为版本不兼容（例如，您正在使用Oracle版本低于11g）这可能适用于您：

with table_fields (type, name, label) as 
(
    select 'ORG', 'text1', 'organisation' from dual union all 
    select 'ORG', 'text2', 'location' from dual union all 
    select 'PERS', 'text1', 'manager' from dual union all 
    select 'PERS', 'text2', 'gender' from dual union all 
    select 'PERS', 'text3', 'age' from dual 
), 
table_data (type, id, text1, text2, text3, text4) as 
(
    select 'ORG', 'Sven', 'HR', 'Brussels', null, null from dual union all 
    select 'PERS', 'Ludo', 'theo', 'male', '43', null from dual union all 
    select 'ORG', 'Sara', 'MR', 'Barcelona', null, null from dual 
) 
select tf.type, tf.name, tf.label, td.id id_table_data, 
     case 
     when tf.name = 'text1' then td.text1 
     when tf.name = 'text2' then td.text2 
     when tf.name = 'text3' then td.text3 
     when tf.name = 'text4' then td.text4 
     else null 
     end value 
    from table_fields tf 
inner join table_data td on (td.type = tf.type);