Dynamic alias of a column with AS-CodePudding

I'm working with some store procedures, one in particular, requires me to use a condition for a specific field of the select. My select is like this:

    acc.AccountNum AS [Voucher_ID],
    pol.Number AS [Policy_Number],
    veh.Vehicle AS [VIN],

What I'm trying to do is change the column alias to the AS dynamically, which then amends based on a condition, I tried to insert an if like this:

acc.AccountNum AS If(@x = 1){[Voucher_ID]} else {[Voucher_ID2]},

But it does not work, I also tried a case but that didn't work either, is there a way to do this or do I have to create two distinct selects?

CodePudding user response：

As mentioned by @Larnu in comments, you cannot have dynamic column literals. You can have both aliases and pick up based on the nullability.

CASE @x = 1 then acc.AccountNum  ELSE NULL END AS [Voucher_ID],
CASE @x <> 1 OR @x IS NULL  then acc.AccountNum ELSE NULL END AS [Voucher_ID2],
    pol.Number AS [Policy_Number],
    veh.Vehicle AS [VIN],

CodePudding user response：

An alias must be a literal. this means that what was requested in my application is only feasible in one way: Create 2 distinct selects, and insert the required condition before the select, like this:

IF @x = 1 
SELECT acc.AccountNum AS [Voucher_ID],
pol.Number AS [Policy_Number],
veh.Vehicle AS [VIN] 
FROM program WHERE ...

IF @x = 2
SELECT acc.AccountNum AS [Voucher_ID2],
pol.Number AS [Policy_Number],
veh.Vehicle AS [VIN] 
FROM program WHERE ...