Parametrizing TOP value in tsql and pyodbc

Question

I try to parametrize number of top rows to get from table.

I tried it with

db.cursor.execute(
        \'\'\'
        SELECT TOP ? VALUE FROM mytable 
           


        

Answer 1

You can use string formatting for the TOP (and a proper parameter for the WHERE) provided that top_limit is an int so there is very little danger of SQL Injection issues.

Answer 2

You can parameterize top by surrounding the value with parenthesis:

DECLARE @Top int = 5;

With Tally(N) AS
(
    SELECT ROW_NUMBER() OVER(ORDER BY @@SPID)
    FROM sys.objects
)

-- This works just fine
SELECT TOP (@Top) N
FROM Tally;

-- This will raise an error: Incorrect syntax near '@Top'
SELECT TOP @Top N 
FROM Tally;

Applied to the code you've posted:

SELECT TOP (?) VALUE 
FROM mytable 
WHERE param = ?