SQL Statement - How to write a WHERE clause with wildcard-CodePudding

I have a c# application that includes a sql query that includes in part, this WHERE clause:

                        WHERE 
                        A.Location=@Location
                        AND
                        Widgets.Branch=@Branch

The requirements have changed such that users can ask to see ALL Branches. I know I can write an if statement to see if i have a branch parameter that's been passed in... and then have a different select statement that omits the AND clause for the branch altogether. But I'm wondering if there's a simpler way to do this? Could I pass in some sort of a wildcard? I tried '*' or '%' but that doesn't seem to be the right syntax. I know % is used with the LIKE...

Any suggestions / tips would be appreciated.

EDIT 1

So I'm trying to figure out how to use the

WHERE 
    A.Location = @Location
AND
    (@Branch IS NULL OR Widgets.Branch = @Branch)

approach.

My code in part looks like this:

 using (var conn = new SqlConnection(connectionString))
 {
      activityByUserType = conn.Query<ActivityDetailsByUserTypes>(
      @"
                SELECT 
                    ReportRefreshDate,
                    other fields...
                FROM 
                (
                        SELECT
                            fields
                        FROM table1 A
                        INNER JOIN Widgets
                            ON LOWER(fieldAA) = LOWER(A.fieldAA)
                        WHERE 
                           A.Location=@Location
                        AND
                          Widgets.Branch=@Branch
                  ) DetailedResults
                 GROUP BY ReportRefreshDate;
                ",
                new { Branch=branchId, Location = LocationId, RefreshDate = dateRange}).ToList();
        }
        return activityByUserType;

As you can see, I'm creating a new query object ... and passing a list of parameters to it at the end of the code block.

I changed the logic to add this if statement before the USING()

        if (branchId.Equals("allbranches")) {
            branchId=null;
        }

But that doesn't seem to really work.

CodePudding user response：

You could check if the parameter is null in the WHERE clause:

    WHERE 
        A.Location = @Location
    AND
        (@Branch IS NULL OR Widgets.Branch = @Branch)

This won't filter the branch when @Branch parameter is null.

CodePudding user response：

You could explicitly check for an asterisk in the query itself:

@Branch IN ('*', Widgets.Branch)

This way, if you pass @Branch=*, the column is ignored, and otherwise it's compared to the value of the column.

CodePudding user response：

May be something like

(@Branch IS NULL OR widgets.Branch = @Branch)