Update and Insert Stored Procedure - sql

Question

I want to create a stored procedure that performs insert or update operation on a column if
that column does not contains a value that already exists in database it should allow insert when COUNT(field) = 0 or update when COUNT(field)=0 or 1 And I should know that either of these operation is performed or not.
Please solve my problem using COUNT not Exists because that won't work for UPDATE.
I am working in ASP.net - I have two columns of a table that are needed to be kept unique without using the unique constraint. So I want a procedure like this:
create proc usp_checkall #field1 varchar(20),
#field2 varchar(20),
#ID int,
#count int output
Now your query on updating/inserting #field1 & #field2 on basis of #id

Answer 1

If you happen to have SQL Server 2008, you could also try:
MERGE dbo.SomeTable AS target
USING (SELECT #ID, #Field_1, #Field_2) AS source (ID, Field_1, Field_2)
ON (target.ID = source.ID)
WHEN MATCHED THEN
UPDATE SET Field_1 = source.Field_1, Field_2 = source.Field_2
WHEN NOT MATCHED THEN
INSERT (ID, Field_1, Field_2)
VALUES (source.ID, source.Field_1, source.Field_2)

Answer 2

Use:
INSERT INTO your_table
(column)
VALUES
([ your_value ])
WHERE NOT EXISTS (SELECT NULL
FROM your_table
WHERE t.column = [ your_value ])
That will work on SQL Server, MySQL, Oracle, Postgres. All that's needed is to use the db appropriate variable reference. IE: For MySQL & SQL Server:
INSERT INTO your_table
(column)
VALUES
( #your_value )
WHERE NOT EXISTS (SELECT NULL
FROM your_table
WHERE t.column = #your_value)
To see if anything was inserted, get the value based on ##ROWCOUNT if using SQL Server. Use SQL%ROWCOUNT if you are using Oracle.

Answer 3

if Exists select * from Yourtable WHere Your Criteria
begin
update ...
end
else
begin
insert ...
end

Answer 4

This kind of approach will do the trick. #AlreadyExisted could be an OUTPUT parameter on the sproc for your calling code to check once it's returned.
DECLARE #AlreadyExisted BIT
SET #AlreadyExisted = 0
IF EXISTS(SELECT * FROM YourTable WHERE YourField = #FieldValue)
BEGIN
-- Record already exists
SET #AlreadyExisted = 1
UPDATE YourTable
SET....
WHERE YourField = #FieldValue
END
ELSE
BEGIN
-- Record does not already exist
INSERT YourTable (YourField,....) VALUES (#FieldValue,.....)
END