Select statment from multiple tables, with variable input

Question

I have two tables: AreaCode and EquipmentNumber.

+------------------------------------+
| AreaCd                             |
|---         


        

Answer 1

SELECT e.Number, e.Type, a.Code
FROM EqNum e INNER JOIN AreaCd a
ON e.AreaId = a.AreaId
WHERE (@Number IS NULL OR e.Number = @Number)
AND (@Type IS NULL OR e.Type = @Type)
AND (@Code IS NULL OR a.Code = @Code)

To learn how to use parameters with ADO.NET, click here.

Setting parameters would look something like this:

command.Parameters["@Number"].Value = (string.IsNullOrEmpty(number) ? (object) DBNull.Value : number);