Question

以下存储过程无法捕捉到正确的条件。如果我提交两个图像，它会正确地写入两个图像。如果我上传1张图片并留空，则会将空白保存为空，覆盖现有数据。最后，如果我将两者都留空，则会保留空白覆盖现有数据。任何帮助都会很棒。感谢。

STORED PROC

ALTER PROCEDURE fstage.spUpdateCMSTrendLanding

(
@TrendLandingText nvarchar(max),
@TrendGuideLandingImage1 nvarchar(max),
@TrendGuideLandingImage2 nvarchar(max)

)

AS
BEGIN

SET NOCOUNT ON;

IF @TrendGuideLandingImage1 IS NULL AND @TrendGuideLandingImage2 IS NULL
    BEGIN
        UPDATE fstage.staticCMS SET TrendGuideLanding = @TrendLandingText;
    END

If (@TrendGuideLandingImage1 IS NOT NULL) AND (@TrendGuideLandingImage2 IS NOT NULL) 
    BEGIN
        UPDATE fstage.staticCMS SET TrendGuideLanding = @TrendLandingText, TrendGuideLandingImage1=@TrendGuideLandingImage1, TrendGuideLandingImage2=@TrendGuideLandingImage2;
    END

If (@TrendGuideLandingImage1 IS NOT NULL) AND (@TrendGuideLandingImage2 IS NULL)
    BEGIN
        UPDATE fstage.staticCMS SET TrendGuideLanding = @TrendLandingText, TrendGuideLandingImage1=@TrendGuideLandingImage1;
    END

If (@TrendGuideLandingImage2 IS NOT NULL) AND (@TrendGuideLandingImage1 IS NULL)
    BEGIN
        UPDATE fstage.staticCMS SET TrendGuideLanding = @TrendLandingText, TrendGuideLandingImage2=@TrendGuideLandingImage2;
    END

END

Answer 1

你的NULL是空字符串。不是数据库NULL值。空字符串是一个值。

这意味着代码始终使用相同的条件

在proc的顶部添加：

SELECT 
  @TrendGuideLandingImage1 = NULLIF(@TrendGuideLandingImage1, ''),
  @TrendGuideLandingImage2 = NULLIF(@TrendGuideLandingImage2, '')

或添加默认值，不要在客户端代码中设置参数

ALTER PROCEDURE fstage.spUpdateCMSTrendLanding
    @TrendLandingText nvarchar(max),
    @TrendGuideLandingImage1 nvarchar(max) = NULL,
    @TrendGuideLandingImage2 nvarchar(max) = NULL
AS

Answer 2

尝试使用ISNull

IF IsNull(@TrendGuideLandingImage1,"") AND IsNull(@TrendGuideLandingImage2,"") =""
  BEGIN
    UPDATE fstage.staticCMS SET TrendGuideLanding = @TrendLandingText;
  END

Answer 3

您可以使用UPDATE和NULLIF将您的程序重写为单个ISNULL语句。

CREATE PROCEDURE fstage.spUpdateCMSTrendLanding
(
    @TrendLandingText nvarchar(max),
    @TrendGuideLandingImage1 nvarchar(max),
    @TrendGuideLandingImage2 nvarchar(max)
)
AS
    UPDATE fstage.staticCMS
    SET TrendGuideLanding = @TrendLandingText
    ,TrendGuideLandingImage1
        = ISNULL(NULLIF(@TrendGuideLandingImage1, ''), TrendGuideLandingImage1)
    ,  TrendGuideLandingImage2
        = ISNULL(NULLIF(@TrendGuideLandingImage2, ''), TrendGuideLandingImage2)

SQL存储过程IF语句未捕获空值和正确条件

STORED PROC

3 个答案: