Question

Below I have a snippet of code from a stored procedure I’m trying to make dynamic. Meaning I want to run the EXEC('select * from table_name WHERE filter=something') to return a result set to my web service. The week_start_date field in my table that I’m querying is a datetime field, not a date field. How do I properly append the datetime parameter to the dynamic SQL so it interprets it correctly in the query? Also, if you have suggestions on how to make the code cleaner, I’ll take advice.

When I look at the data, I have values that look like this:

2012-08-10 00:00:00.000

T-SQL code that is not working:

ALTER PROCEDURE [dbo].[logged_time_by_week]
    @week_start_date_filter datetime = null
AS
BEGIN

….

    DECLARE @select_clause nvarchar(4000);
    DECLARE @from_clause nvarchar(4000);
    DECLARE @where_clause nvarchar(4000);
    DECLARE @order_clause nvarchar(4000);

    SET @select_clause = 
        ' SELECT '
        + ' [sunday_hours],'
        + ' [monday_hours],'
        + ' [tuesday_hours],'
        + ' [wednesday_hours],'
        + ' [thursday_hours],'
        + ' [friday_hours],'
        + ' [saturday_hours]'

    SET @from_clause =
        ' FROM '
        + ' [timesheet_row] '

    SET @where_clause = ''

    IF @week_start_date_filter IS NOT NULL AND @week_start_date_filter != ''
    BEGIN 
        IF @where_clause != ''
        BEGIN
            SET @where_clause = @where_clause + ' AND ' 
        END
        SET @where_clause = @where_clause + ' [week_start_date] = ' + CONVERT(nvarchar, @week_start_date_filter)
    END

    IF @where_clause != '' 
    BEGIN
        SET @where_clause = ' WHERE ' + @where_clause
    END

    SET @order_clause = ' ORDER BY [' + @sort_column + '] ' + @sort_direction

    EXEC(@select_clause + @from_clause + @where_clause + @order_clause)

Answer 1

Easiest way to troubleshoot these kinds of errors is to print out the generated sql to see why it’s failing.

Just by looking at your query i believe you just need to fix the quotes around the @week_start_date_filter variable.

declare @week_start_date_filter datetime = getdate();
print ' [week_start_date] = ''' + CONVERT(nvarchar, @week_start_date_filter) + '''';

Also as a side note, I’d recommend instead to use parameterized sql if you have to use dynamic sql. Here’s an example using sys.objects since i don’t know the schema of your table.

DECLARE
    @week_start_date_filter datetime    = (SELECT TOP(1) [create_date] FROM sys.objects),
    @sort_column            sysname     = N'create_date',
    @sort_direction         nvarchar(3) = N'ASC';


    DECLARE @select_clause nvarchar(4000);
    DECLARE @from_clause nvarchar(4000);
    DECLARE @where_clause nvarchar(4000);
    DECLARE @order_clause nvarchar(4000);

    SET @select_clause = 
        ' SELECT TOP(1) '
        + ' *';

    SET @from_clause =
        ' FROM '
        + ' sys.objects'

    SET @where_clause = ''

    IF @week_start_date_filter IS NOT NULL AND @week_start_date_filter != ''
    BEGIN 
        IF @where_clause != ''
        BEGIN
            SET @where_clause = @where_clause + ' AND ' 
        END
        SET @where_clause = @where_clause + ' [create_date] = @date_filter'
    END

    IF @where_clause != '' 
    BEGIN
        SET @where_clause = ' WHERE ' + @where_clause
    END

    SET @order_clause = ' ORDER BY [' + @sort_column + '] ' + @sort_direction

    DECLARE
        @SQL    nvarchar(max) = @select_clause + @from_clause + @where_clause + @order_clause,
        @Params nvarchar(200) = N'@date_filter datetime';


    EXEC sp_executesql
        @stmt        = @SQL,
        @params      = @Params,
        @date_filter = @week_start_date_filter;