虽然游标通常被认为是可怕的邪恶，但我相信FAST_FORWARD游标是一个例子——在TSQL中你能得到的最接近FOREACH的东西。

您的select count和select max应该来自您的表变量，而不是实际的表

DECLARE @i int
DECLARE @PractitionerId int
DECLARE @numrows int
DECLARE @Practitioner TABLE (
    idx smallint Primary Key IDENTITY(1,1)
    , PractitionerId int
)

INSERT @Practitioner
SELECT distinct PractitionerId FROM Practitioner

SET @i = 1
SET @numrows = (SELECT COUNT(*) FROM @Practitioner)
IF @numrows > 0
    WHILE (@i <= (SELECT MAX(idx) FROM @Practitioner))
    BEGIN

        SET @PractitionerId = (SELECT PractitionerId FROM @Practitioner WHERE idx = @i)

        --Do something with Id here
        PRINT @PractitionerId

        SET @i = @i + 1
    END

您似乎想要使用游标。尽管大多数时候最好使用基于集合的解决方案，但有时CURSOR是最佳解决方案。在不了解你的实际问题的情况下，我们帮不了你:

DECLARE @PractitionerId int

DECLARE MY_CURSOR CURSOR 
  LOCAL STATIC READ_ONLY FORWARD_ONLY
FOR 
SELECT DISTINCT PractitionerId 
FROM Practitioner

OPEN MY_CURSOR
FETCH NEXT FROM MY_CURSOR INTO @PractitionerId
WHILE @@FETCH_STATUS = 0
BEGIN 
    --Do something with Id here
    PRINT @PractitionerId
    FETCH NEXT FROM MY_CURSOR INTO @PractitionerId
END
CLOSE MY_CURSOR
DEALLOCATE MY_CURSOR

虽然游标通常被认为是可怕的邪恶，但我相信FAST_FORWARD游标是一个例子——在TSQL中你能得到的最接近FOREACH的东西。

我想说，除了列idx在你选择的表中不存在之外，一切都可能正常。也许你想从@从业者中选择:

WHILE (@i <= (SELECT MAX(idx) FROM @Practitioner))

因为在上面的代码中是这样定义的:

DECLARE @Practitioner TABLE (
    idx smallint Primary Key IDENTITY(1,1)
    , PractitionerId int
)

假设列practictionerid是唯一的，那么您可以使用下面的循环

DECLARE @PractitionerId int = 0
WHILE(1 = 1)
BEGIN
  SELECT @PractitionerId = MIN(PractitionerId)
  FROM dbo.Practitioner WHERE PractitionerId > @PractitionerId
  IF @PractitionerId IS NULL BREAK
  SELECT @PractitionerId
END