Inline Conditional Statement in Stored Procedure

Here is the pseudo-code for my inline query in my code:

select columnOne
from myTable
where columnOne = '#variableOne#'
  if len(variableTwo) gt 0
      and columnTwo = '#variableTwo#'
  end

I would like to move this into a stored procedure but am having trouble building the query correctly. I assume it would be something like

select columnOne
from myTable
where columnOne = @variableOne
  CASE
  开发者_如何学Python  WHEN len(@variableTwo) <> 0 THEN and columnTwo = @variableTwo
  END

This is giving me a syntax error.

Could someone tell me what I've got wrong.

Also, I would like to keep it to only one query and not just have one if statement. Also, I do not want to build the sql in the stored procedure and run Exec() on it.

Switch up your logic and you can get the result you want.

select columnOne
from myTable
where columnOne = @variableOne
and (len(@variableTwo) = 0 or columnTwo = @variableTwo)