安装了32位版本的mysql。我附上了一些表的快照并进行了解释。我想你会很容易发现我的问题。expalincutting\u inventory tableswing\u effi tableswing\u output tableid\u cutting\u inventory table输出表ID\u切割\u库存表

• challan\u接收\u ssd和challan\u关闭\u ssd列存储日期*challan\u接收\u sst和challan\u关闭\u sst列存储时间

不要使用mysql接口！

SELECT  Line
            FROM  sewing_effi
            WHERE  DT='$dt'
            ORDER BY  Line ASC"

的数据类型是什么 DT ? (请提供 SHOW CREATE TABLE )
假设 DT 是一个 DATE ，那么你需要 INDEX(DT, Line) 为了提高效率。
为此：

SELECT  buyer.Buyer,ordr.ordr,ordr.Ship_Date,colour.Colour,sewing_effi.OP,
                sewing_effi.HEL,sewing_effi.Target,sewing_effi.TWH,sewing_effi.Line,
                sid_cutting_inventory.DT,
                SUM(cutting_inventory.qc_pass) AS Input,
                SUM(sewing_output.QC_Pass) AS Toutput, SUM(sewing_output.Recieved) AS Recv
            FROM  cutting_inventory
            INNER JOIN  sid_cutting_inventory
                ON cutting_inventory.SID=sid_cutting_inventory.SID
            LEFT JOIN  buyer  ON cutting_inventory.Buyer=buyer.CBuyer
            LEFT JOIN  ordr  ON cutting_inventory.Buyer=ordr.CBuyer
              AND  cutting_inventory.Ordr=ordr.COrdr
            INNER JOIN  colour  ON cutting_inventory.Buyer=colour.CBuyer
              AND  cutting_inventory.Ordr=colour.COrdr
              AND  cutting_inventory.Colour=colour.CColour
            LEFT JOIN  sewing_output  ON sewing_output.Barcode=cutting_inventory.Barcode
            JOIN  sewing_effi  ON sewing_effi.Line=sid_cutting_inventory.Line
            WHERE  sewing_effi.Line ='$li'
              AND  sewing_effi.DT='$dt'
              AND  ordr.Ship_Status='0'
              AND  sid_cutting_inventory.Challan_Close_SS='0'
              AND  sid_cutting_inventory.DT NOT BETWEEN '2017-01-31  7:00:00'
                                                    AND '2018-03-31 23:00:00'
            GROUP BY  sewing_effi.Line, buyer.Buyer, ordr.ordr,colour.Colour
            ORDER BY  sewing_effi.Line"
                          )

我觉得混合起来很混乱 LEFT JOIN 以及 INNER JOIN . 请提供 EXPLAIN SELECT ... 我来猜猜看。

sewing_effi:  INDEX(Line, DT)  -- in either order
sid_cutting_inventory:  INDEX(Challan_Close_SS, DT) -- in this order

您是否安装了32位或64位版本的mysql？