Copy data depending on parameter - tsql

Question

I'm having a total blackout right now and hope someone could help me. In my application users are able to copy data from one table to another by clicking on buttons. The data from source table is being retrieved differently, depending on the page where the user clicks on a copy button.
My tables
tabPlanning
+--------------+-------------+--------+--------+--------------+
| PlanningId | RequestId | Field1 | Field2 | Field3 |
|--------------|-------------|--------|--------|--------------|
| Primary key | Foreign key | | | |
+--------------+-------------+--------+--------+--------------+
| INT | INT | DATE | BIGINT | NVARCHAR(20) |
+--------------+-------------+--------+--------+--------------+
tabPlanningCopy
+------------------+-------------+--------+--------+--------------+
| PlanningCopyId | RequestId | Field1 | Field2 | Field3 |
|------------------|-------------|--------|--------|--------------|
| Primary Key | Foreign Key | | | |
+------------------+-------------+--------+--------+--------------+
| INT | INT | DATE | BIGINT | NVARCHAR(20) |
+------------------+-------------+--------+--------+--------------+
My stored procedure
spCopyPlanning
spCopyPlanning copies data from tabPlanning to tabPlanningCopy depending on parameters:
ALTER PROCEDURE dbo.spCopyPlanning
#PlanningId INT = NULL
#RequestId INT = NULL
AS
BEGIN
IF #PlanningId IS NOT NULL
BEGIN
IF EXISTS (SELECT * FROM tabPlanning WHERE RequestId = #RequestId)
BEGIN
INSERT INTO tabPlanningCopy(RequestId, Field1, Field2, Field3)
SELECT RequestId,
Field1,
Field2,
Field3
FROM tabPlanning
WHERE PlanningId = #PlanningId
END
END
ELSE
BEGIN
IF EXISTS (SELECT * FROM tabPlanning WHERE RequestId = #RequestId)
BEGIN
INSERT INTO tabPlanningCopy(RequestId, Field1, Field2, Field3)
SELECT RequestId,
Field1,
Field2,
Field3
FROM tabPlanning
WHERE RequestId = #RequestId
END
END
END
-- #PlanningId IS NOT NULL -> copy the row with PlanningId = #PlanningId
-- #PlanningId IS NULL -> copy the row with RequestId = #RequestId
The procedure is working as it is written right now. However, I don't think this is the nicest approach to get what I want (I hate redundancy!). I'm pretty sure it can be achieved by expanding the WHERE statement but I don't have any clue right now how to solve this. Could anyone lead me to a solution to get rid of my redundant code?

Answer 1

It is redundant because everything but the WHERE clause is identical except where it evaluates whether or not a parameter is null. As parameters are or are not null, it's a simple matter of specifying two pairs of conditions in the Where. Try the following:
ALTER PROCEDURE dbo.spCopyPlanning
#PlanningId INT = NULL
#RequestId INT = NULL
AS
BEGIN
IF EXISTS (SELECT * FROM tabPlanning WHERE RequestId = #RequestId)
BEGIN
INSERT INTO tabPlanningCopy(RequestId, Field1, Field2, Field3)
SELECT RequestId,
Field1,
Field2,
Field3
FROM tabPlanning
WHERE (#PlanningId is not null
and PlanningId = #PlanningId)
or (#PlanningId is null
and RequestId = #RequestId)
END
END