Question

I’m trying to create a simple stored procedure to count the number of empty records in my database:

CREATE PROCEDURE dbo.cnt_empty 
    @col NVARCHAR(10)
AS
BEGIN
    SET NOCOUNT ON;
    SET XACT_ABORT ON;

        SELECT COUNT(@col) AS cnt
        FROM dbo.mytable
        WHERE @col = ''

END
GO

EXECUTE dbo.cnt_empty @col = N'field1' -- nvarchar(10)

I returns 0 for all the columsn I tested. What is wrong with this procedure?

Answer 1

Your string is not being assessed as the column name, so you are actually running “where ‘field1’ = ””

You need to do something like this

set @sql = 'select @cnt = COUNT(*) from [' + @tableSchema + '].[' + @tableName +
    '] where [' + @columnName + '] is not null';
-- print @sql; --uncomment for debugging
exec sp_executesql @sql, N'@cnt bigint output', @cnt = @cnt output;

Look at http://blog.hoegaerden.be/2009/02/15/script-find-all-empty-columns-in-database/ for the full script.