The SQL MERGE statement, introduced in SQL-92, is the best way to update columns in a table if the the row exists, or insert a new row if the row does not exist. This is performed in a single T-SQL statement.

The source code below updates or inserts values into a Prices table that has a Name and Price column.

CREATE PROCEDURE [dbo].[UpsertPrice]
(
  @name nvarchar(MAX),
  @price decimal(18, 2)
)
AS
BEGIN
  SET NOCOUNT ON; 

  MERGE Prices AS target
  USING (SELECT @name, @price) AS source (Name, Price)
  ON (target.Name = source.Name)
  WHEN MATCHED THEN
    UPDATE SET target.Price = source.Price
  WHEN NOT MATCHED THEN
    INSERT (Name, Price)
    VALUES (source.Name, source.Price);
END;

This combination of update-or-insert values is known by the portmanteau ‘upsert’. I read it on the Internet so it must be true.