Question

我有一个MySQL存储过程，其中包含以下WHILE语句。

我已经确认@RowCnt是1，而@MaxRows是6090，但是经过进一步调试后，我意识到WHILE语句经历了一次迭代而没有继续;所以我希望对可能造成这种情况的事情有所了解。

完全披露：我将它从SQL Server移植到MySQL存储过程，这是我以前从未接受过的。（意思是SQL Server，移植OR存储过程..）

WHILE @RowCnt <= @MaxRows DO
    SELECT @currentReadSeq:=ReadSeq, @currentReadStrength:=ReadStrength, @currentReadDateTime:=ReadDateTime, @currentReaderID:=ReaderID FROM tblTempRead WHERE rownum = @RowCnt;

    IF ( ((@lastReadSeq + 10) > @currentReadSeq) AND (@lastReaderId = @currentReaderId) ) THEN 
        SET @lastReadSeq = @currentReadSeq, @lastReadStrength = @currentReadStrength, @lastReadDateTime = @currentReadDateTime, @lastReaderID = @currentReaderID;
    ELSE
        INSERT INTO tblreaddataresults (SiteID, ReadDateTimeStart, ReadDateTimeEnd, ReadSeqStart, ReadSeqEnd, ReaderID, DirectSeconds) VALUES ('1002', @saveReadDateTime, @lastReadDateTime, @saveReadSeq, @lastReadSeq, @lastReaderID, timestampdiff(SECOND,@saveReadDateTime,@lastReadDateTime));

        SET @saveReadSeq = @currentReadSeq, @saveReadStrength = @currentReadStrength, @saveReadDateTime = @currentReadDateTime, @saveReaderID = @currentReaderID;

        SET @lastReadSeq = @saveReadSeq, @lastReadStrength = @saveReadStrength, @lastReadDateTime = @saveReadDateTime, @lastReaderID = @saveReaderID;
    END IF;

    SET @RowCnt = @RowCnt+1;
END WHILE;

Answer 1

尝试此构造

WHILE (@RowCnt <= @MaxRows)
BEGIN
    SELECT @currentReadSeq:=ReadSeq, @currentReadStrength:=ReadStrength, @currentReadDateTime:=ReadDateTime, @currentReaderID:=ReaderID FROM tblTempRead WHERE rownum = @RowCnt;

    IF (((@lastReadSeq + 10) > @currentReadSeq) AND (@lastReaderId = @currentReaderId))
        BEGIN
        SET @lastReadSeq = @currentReadSeq, @lastReadStrength = @currentReadStrength, @lastReadDateTime = @currentReadDateTime, @lastReaderID = @currentReaderID;
        END
    ELSE
        BEGIN
        INSERT INTO tblreaddataresults (SiteID, ReadDateTimeStart, ReadDateTimeEnd,ReadSeqStart, ReadSeqEnd, ReaderID, DirectSeconds) VALUES ('1002',@saveReadDateTime, @lastReadDateTime, @saveReadSeq, @lastReadSeq, @lastReaderID,timestampdiff(SECOND,@saveReadDateTime,@lastReadDateTime));
        SET @saveReadSeq = @currentReadSeq, @saveReadStrength = @currentReadStrength, @saveReadDateTime = @currentReadDateTime, @saveReaderID = @currentReaderID;
        SET @lastReadSeq = @saveReadSeq, @lastReadStrength = @saveReadStrength,@lastReadDateTime = @saveReadDateTime, @lastReaderID = @saveReaderID;
        END
    SET @RowCnt = @RowCnt+1;
END

使用IF / THEN / ELSE的MySQL存储过程

1 个答案: