insert a record into a table where there IS a record in another

I have two tables:

Products & Product_Categories

I want to INSERT a record into Product_Categories if there is not already one for that product_ID in the Product_categories table for each product_ID in the Products table.

Product_Categories field should have the product_ID and a value of 0 for Category_ID



vbnetcoderAsked:
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jimtpowersConnect With a Mentor Commented:
I have two tables:

Products & Product_Categories

I want to INSERT a record into Product_Categories if there is not already one for that product_ID in the Product_categories table for each product_ID in the Products table.

Product_Categories field should have the product_ID and a value of 0 for Category_ID

INSERT INTO Product_Categories (Category_ID, Product_ID)
SELECT '0',
p.Product_ID
FROM Products AS p
WHERE (p.Product_ID NOT IN (SELECT DISTINCT Product_ID FROM Product_Categories))
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MuffyBunnyCommented:
INSERT INTO Product_Categories(whatever fields are in this table) 
SELECT whatever fields you need for Product_Categories 
FROM Products p LEFT OUTER JOIN Product_Categories pc ON (p.productId = pc.productId) 
WHERE some_field_from_ProductCategories IS NULL

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TheTullCommented:
Have you tried adding a where clause like this:

where product_id not in (select distinct product_Id from product_categories)

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Roman GhermanSenior Software EngineerCommented:
Hi,
Try this

INSERT INTO Product_Categories
(col1, col2)
SELECT
 col1,
 col2
FROM Products
WHERE
product_ID  NOT IN (SELECT product_ID FROM Product_Categories )
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MuffyBunnyCommented:
Depending on the number of records you expect to be returned from Products, NOT IN is a really inefficient way to do that. At the very least you should use NOT EXISTS. The most efficient way is with a LEFT OUTER JOIN and then checking for NULL in the WHERE.
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gery128Commented:
you can use ADO.NET command with ExecuteScalar method of command object to check if the returning Category_ID is 0 or something other and if not then use another query with ExecuteNonQuery to insert the record.

like this:
cmd.CommandText = "select Category_ID from Product_Categories where Product_ID="@prodId";
int catId = (int)cmd.ExecuteScalar();
if(catId==0)
cmd.CommandText =@insert into Product_catergories...";
cmd.ExecuteNonQuery();


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vbnetcoderAuthor Commented:
THANK YOU everbody but this is the solution I used
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