I have the following procedure:
CREATE PROCEDURE sp_types
@type varchar(100)
AS
BEGIN
DECLARE @products table(productId int)
IF @type = 'Merchandise'
BEGIN
INSERT INTO @products
SELECT productId
FROM dbo.product
WHERE type = @type
END
ELSE IF @type = 'Electronics'
BEGIN
INSERT INTO @products
SELECT productId
FROM dbo.product
WHERE type = @type
END
ELSE IF @type = 'Home'
BEGIN
INSERT INTO @products
SELECT productId
FROM dbo.product
WHERE type = @type
END
ELSE
BEGIN
INSERT INTO @products
SELECT productId
FROM dbo.product
WHERE type = @type
END
/* here we have logic to convert all the productids in the @products table into an XML format
<products>
<productId>1</productId>
<productId>2</productId>
....
....
....
<productId>100</productId>
</products>
*/
/* after we get the XML string, it is passed to another procedure to print out details about the products */
EXEC sp_products_list @xml = @productXml
END /* procedure ends here */
Here's the sp_products_list
procedure:
CREATE PROCEDURE sp_products_list
@xml XML
AS
BEGIN
DECLARE @products TABLE (productId int)
INSERT INTO @products
SELECT @xml.value('productId','int')
FROM @xml.nodes('products')
/* Select statement */
SELECT
a.productId, a.productName,
b.productRegion, b.ProductQuantity,
c.productSupplier
FROM
products a
JOIN
productRegion b ON a.productid = b.productid
JOIN
productSupplier c ON c.productRegion = b.productRegion
WHERE
a.productId IN (SELECT productId FROM @products)
END /* procedure end */
The sp_products_list
is called by many other procedures other than the sp_types
procedure. I have a requirement wherein when I pass a type of 'Merchandise' to the sp_types
procedure, then I need some additional columns like productSupplierRegion
, productSupplierCount
etc. displayed.
But for the rest of the types, I only need to display what the select statement in the sp_products_list
procedure currently displays.
If I simply add the columns that I need to the select statement in the current sp_products_list
procedure then they will be displayed for any type that is passed to the sp_types
procedures and that is not what I want.
My solution: one of the solutions I could think of was receiving a @type variable as an input in the sp_products_list
procedure and having an if-else statement for the select statement. If the type of 'Merchandise' is passed in then display the select with additional columns otherwise display the regular columns.
The problem I might face in the future with this approach is what if we want to add different types of columns for different @type
variables that are passed in. In that case, I'll have to have to do multiple if-else statements for each type. I was planning on using dynamic SQL but my idea was shot down since my team is not a huge fan of dynamic SQL.
Now I'm trying to find a robust solution for this problem that might work in any scenario. Any thoughts or suggestions? Thank you!
CodePudding user response:
I suggest you rewrite sp_products_list
as a table-valued function, then you can just join it with any extra columns you need
CREATE OR ALTER FUNCTION dbo.products_list ( @productId int )
RETURNS TABLE
AS RETURN
SELECT
p.productId, p.productName,
pr.productRegion, pr.ProductQuantity,
ps.productSupplier
FROM
products p
JOIN
productRegion pr ON p.productid = pr.productid
JOIN
productSupplier ps ON ps.productRegion = pr.productRegion
WHERE
p.productId = @productId;
GO
Then you simply use that function in each of the procedures. For example.
CREATE PROCEDURE ProductByType
@type varchar(100)
AS
IF @type = 'Merchandise'
BEGIN
SELECT pl.*, p.OtherColumns, t.OtherTablesColumns
FROM dbo.product p
CROSS APPLY dbo.products_list (p.productId) pl
LEFT JOIN OtherTable t ON SomeCondition
WHERE p.type = @type;
END;
ELSE
BEGIN
SELECT pl.*
FROM dbo.product p
CROSS APPLY dbo.products_list (p.productId) pl
WHERE p.type = @type;
END;
You may find it more performant to push the @type
selection into the function also. Then you can simply do
SELECT pl.*
FROM dbo.products_list_by_type (@type) pl
The server will remove any columns that are not needed from the query plan.