Oracle SQL相当于Excel的索引匹配

我想了解如何使用ORACLE SQL代码来模拟在Excel中可以实现的索引和匹配

表1：

cid  Cname  Age  Height 
001  Mary   E40  E22 
002  Cat    E22  E40

表2：

Fname   CODE     MEAING 
Age     E40      40 years old 
Age     E22      22 years old
Height  E22      5'2 
Height  E40     5'4

目标：

将

年龄

和

身高

的值替换为表2中的

含义

预期结果：

cid  Name  Age           Height
001  Mary  40 years old  5'2 
002  Cat   22 years old  5'4

在Excel中执行此操作的当前方式：

---

如何在Oracle中执行相同的操作？

您可以从

表1

连接到

表2

两次，每种数据点类型连接一次：

select t1.cid, t1.cname as name,
  t2_age.meaing as age, t2_height.meaing as height
from table_1 t1
join table_2 t2_age on t2_age.fname = 'Age' and t2_age.code = t1.age
join table_2 t2_height on t2_height.fname = 'Height' and t2_height.code = t1.height

使用CTEs中的样本数据：

with table_1 (cid, cname, age, height) as (
  select '001', 'Mary', 'E40', 'E22' from dual
  union all select '002', 'Cat', 'E22', 'E40' from dual
),
table_2 (fname, code, meaing) as (
  select 'Age', 'E40', '40 years old' from dual
  union all select 'Age', 'E22', '22 years old' from dual
  union all select 'Height', 'E22', '5''2' from dual
  union all select 'Height', 'E40', '5''4' from dual
)
select t1.cid, t1.cname as name,
  t2_age.meaing as age, t2_height.meaing as height
from table_1 t1
join table_2 t2_age on t2_age.fname = 'Age' and t2_age.code = t1.age
join table_2 t2_height on t2_height.fname = 'Height' and t2_height.code = t1.height;

CID NAME AGE          HEIGHT      
--- ---- ------------ ------------
001 Mary 40 years old 5'2         
002 Cat  22 years old 5'4         

或者，您可以加入一次，然后使用条件聚合来选择相关值：

select t1.cid, t1.cname as name,
  max(case when t2.fname = 'Age' then t2.meaing end) as age,
  max(case when t2.fname = 'Height' then t2.meaing end) as height
from table_1 t1
join table_2 t2 on (t2.fname = 'Age' and t2.code = t1.age)
                or (t2.fname = 'Height' and t2.code = t1.height)
group by t1.cid, t1.cname;

CID NAME AGE          HEIGHT      
--- ---- ------------ ------------
001 Mary 40 years old 5'2         
002 Cat  22 years old 5'4         

基本上是一个手动枢轴：

select *
from (
  select t1.cid, t1.cname as name, t2.fname, t2.meaing
  from table_1 t1
  join table_2 t2 on (t2.fname = 'Age' and t2.code = t1.age)
                  or (t2.fname = 'Height' and t2.code = t1.height)
)
pivot (max(meaing) for (fname) in ('Age' as age, 'Height' as height));

CID NAME AGE          HEIGHT      
--- ---- ------------ ------------
001 Mary 40 years old 5'2         
002 Cat  22 years old 5'4