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带In IsNull的Select语句

isnull tsql sql-server

Tempname · 技术社区 · 16 年前

我正在编写一个存储过程,在此过程中我使用的是isNull。如果值为空,我想使用一个select语句作为替换值,这是否可能?

IF ISNULL(@v_FilePrefix, (SELECT @v_FilePrefix = TransactionTypePrefix 
                            FROM [ConfigTransactionType] 
                           WHERE TransactionTypeID = @TransactionTypeID));

2 回复 | 直到 16 年前

Dean Harding 16 年前

IF @v_FilePrefix IS NULL
BEGIN

    SELECT @v_FilePrefix = TransactionTypePrefix
    FROM [ConfigTransactionType]
    WHERE TransactionTypeID = @TransactionTypeID

END

OMG Ponies 16 年前

SELECT @v_FilePrefix = COALESCE(@v_FilePrefix, TransactionTypePrefix)
  FROM [ConfigTransactionType] 
 WHERE TransactionTypeID = @TransactionTypeID

IF @v_FilePrefix IS NULL
BEGIN

   SELECT @v_FilePrefix = TransactionTypePrefix
     FROM [ConfigTransactionType]
    WHERE TransactionTypeID = @TransactionTypeID

END

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