从其他表的串联中选择SQL Server中的特定列

Question

I'm trying to select a specific column based off a value in another table

I have one table with the following columns:

TableA :

Item_Id,Column01,Column02,Column03,Column04,Column05,  

Sample data for TableA respectively:

1,$1.00,$2.00,$3.00,$4.00,$5.00

TableB columns:

 Item_ID,Column  

Data for TableB :

1,05

I want to be able to return the value based on what I have in TableB . Currently I'm concatenating to get the field name, but I don't know how to get the value.

Select 'Column'+TableB.[Column] 
from TableA 
inner join TableB on TableA.Item_Id = TableB.ItemB
WHERE TableA.Item_Id = 1

So for this particular example the query would select column05 from TableA and the result would be $5.00.

Answer 1

You can use the CASE statament

Select CASE TableB.[Column] When '01' THEN TableA.Column01
                            When '02' THEN TableA.Column02
                            When '03' THEN TableA.Column03
                            When '04' THEN TableA.Column04
                            When '05' THEN TableA.Column05
       END as Value
from TableA 
inner join TableB on TableA.Item_Id = TableB.ItemB
WHERE TableA.Item_Id = 1

But the column01 ... column05 of tableA need to be of the same data type, or converted to the same data type.