SQL INSERT but avoid duplicates

Question

I want to do some quick inserts but avoid duplicates into a Table. For argument\'s sake lets call it MarketPrices, I\'ve been experimenting with two ways of doing it but not

Answer 1

I would go for a semantic solution anytime. Your two proposals seem quite obscure to me (though the latter is better than the former).

IF NOT EXISTS (
  SELECT 1
  FROM   MarketPrices 
  WHERE  SecurityCode  = @SecurityCode 
         AND BuyPrice  = @BuyPrice 
         AND SellPrice = @SellPrice
)  
BEGIN
  INSERT MarketPrices 
    (SecurityCode,   BuyPrice,  SellPrice,  IsMarketOpen)
  VALUES 
    (@SecurityCode, @BuyPrice, @SellPrice, @IsMarketOpen)
END

With a conglomerate index over SecurityCode, BuyPrice, SellPrice the EXISTS query should go reasonably fast.

Benchmarking it is a matter of timing a WHILE loop, I would say. Test it and see for yourself.