SQL Server插入（如果不存在）的最佳做法[EXTENDED]

Question

INSERT `locality` (province_id)
SELECT DISTINCT `province_id`
FROM `locality` localreturn
WHERE
   NOT EXISTS (SELECT * FROM `locality` local
              WHERE localreturn.province_id = local.province_id)

If the query tested passes how do i insert a value? a normal insert would be like:

INSERT INTO `locality` (`province_id`) VALUES (1919)

Leeched Source: SQL Server insert if not exists best practice

Answer 1

try

  BEGIN
    IF NOT EXISTS(SELECT * FROM `locality` local WHERE  local.province_id=@id) 
    BEGIN
     INSERT `locality` (province_id) values(@id)
    END
  END