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TSQL – 如果记录存在于单个选择中,则将查询中的值分配给变量

发布时间:2021-01-12 10:46:21 所属栏目:编程 来源:网络整理
导读:我如何改进以下代码只使用一次“选择”? IF EXISTS (SELECT [NUMBER] FROM [TABLE] WHERE [ID_RECORD] = @id_recordBEGIN DECLARE @tmp_variable SELECT @tmp_variable = [NUMBER] FROM [TABLE] WHERE [ID_RECORD] = @id_record SET @other_variable = @tmp_

我如何改进以下代码只使用一次“选择”?

IF EXISTS (SELECT [NUMBER] FROM [TABLE] WHERE [ID_RECORD] = @id_record
BEGIN
   DECLARE @tmp_variable
   SELECT @tmp_variable = [NUMBER] FROM [TABLE] WHERE [ID_RECORD] = @id_record

   SET @other_variable = @tmp_variable
END
ELSE
BEGIN
   SET @other_variable = 0
END

解决方法

试试这个 :
DECLARE @tmp_variable INT
 SET @tmp_variable = ISNULL(( SELECT    [NUMBER]
                              FROM      [TABLE]
                              WHERE     [ID_RECORD] = @id_record
                             ),0)

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