sql - 重置存储过程变量

Question

好吧，显然这不起作用。我收到“'=' 附近的语法错误”错误。是否可以在存储过程中多次更改变量的值？

与此示例类似：

    DECLARE @columnCounter INT
    SET @columnCounter = 0

    DECLARE @columnName VARCHAR(255)
    SET @columnName = 'A'

    WHILE (@columnCounter < 4)
    BEGIN
        IF (@columnCounter == 1)
        BEGIN
            SET @columnName = 'B'
        END
        IF (@columnCounter == 2)
        BEGIN
            SET @columnName = 'C'
        END
        IF (@columnCounter == 3)
        BEGIN
            SET @columnName = 'D'
        END
    END

谢谢你。

Answer 1

是==. Transact-SQL 使用 simple=进行相等比较，如下所示：

DECLARE @columnCounter INT;
SET @columnCounter = 0;

DECLARE @columnName VARCHAR(255);
SET @columnName = 'Set_To_Value_ID';

WHILE (@columnCounter < 4)
BEGIN
    IF (@columnCounter = 1)
    BEGIN
        SET @columnName = 'Set_To_Variable_ID';
    END
    IF (@columnCounter = 2)
    BEGIN
        SET @columnName = 'Changed_In_SP';
    END
    IF (@columnCounter = 3)
    BEGIN
        SET @columnName = 'Set_To_Comment_Input';
    END
    set @columnCounter += 1;
END

Answer 2

IF (@columnCounter == 1)

比较应该只是=,==是多种语言的通用语法，但不是 t-sql。

http://msdn.microsoft.com/en-us/library/ms175118(v=sql.100).aspx