Question

我的数据库中有以下数据

插入数据时我有一些重复的记录。

CREATE TABLE `historical_data` (
  `symbol_name` varchar(70) DEFAULT NULL,
  `current_day` varchar(50) DEFAULT NULL,
  `open_val` varchar(50) 
) ENGINE=MyISAM DEFAULT CHARSET=latin1 ;

Insert Into historical_data values('SBIN','10-DEC-2015','300.10');
Insert Into historical_data values('SBIN','10-DEC-2015','300.10');
Insert Into historical_data values('SBIN','10-DEC-2015','300.10');
Insert Into historical_data values('ACC','10-DEC-2015','1233.10');
Insert Into historical_data values('TATELXSI','10-DEC-2015','1980.10');

您能告诉我如何从表中删除所有重复项吗

重复表示相同的符号和当天相同

http://sqlfiddle.com/#!9/70d96

Answer 1

没有必要这样做。只需按原样运行此查询： -

ALTER IGNORE TABLE `historical_data`
ADD UNIQUE INDEX (`symbol_name`, `current_day`, `open_val` );

这将为您的表添加唯一索引并删除所有正常的行，并确保将来不会插入重复的行。

Answer 2

您可以使用STORED PROCEDURE记下CURSOR以读取每一行，并运行循环以查找任何类似的行，如果找到，您只需要DELETE该特定行行。

Answer 3

您可以向表中添加主键，以便可以在不使用游标的情况下区分重复项，然后通过将表连接到自身来删除它们：

Sub Button2_Click()

Dim i As Integer, TotalEffortEC As Double, TotalNCEC As Double, TotalSizeEC As Double
Dim TotalEffortWB As Double, TotalNCWB As Double, TotalSizeWB As Double

    TotalEffortEC = 0
    TotalNCEC = 0
    TotalSizeEC = 0
    TotalEffortWB = 0
    TotalNCWB = 0
    TotalSizeWB = 0
    i = 3

    With Worksheets("Valid Data")
        Do While .Cells(i, 6).Value <> ""
            If .Cells(i, 7).Value = "WB" Then
                TotalEffortWB = .Cells(i, 23).Value + TotalEffortWB
                TotalNCWB = .Cells(i, 14).Value + TotalNCWB
                TotalSizeWB = .Cells(i, 13).Value + TotalSizeWB
            Else
                TotalEffortEC = .Cells(i, 23).Value + TotalEffortEC
                TotalNCEC = .Cells(i, 14).Value + TotalNCEC
                TotalSizeEC = .Cells(i, 13).Value + TotalSizeEC
            End If
            i = i + 1
        Loop
    End With

    With Worksheets("Summary")
        .Range("A2").Value = (TotalEffortEC + .Range("B10") + .Range("C10")) / TotalNCEC
        .Range("B2").Value = (TotalEffortEC + .Range("B10") + .Range("C10")) / TotalSizeEC
        .Range("A3").Value = (TotalEffortWB + .Range("B11") + .Range("C11")) / TotalNCWB
        .Range("B3").Value = (TotalEffortWB + .Range("B11") + .Range("C11")) / TotalSizeWB
    End With

End Sub

或使用唯一索引：

Sub test()
    Dim Dic As Object: Set Dic = CreateObject("Scripting.Dictionary")
    Dim cl As Range, i&, k, x%, z%
    Dic.comparemode = vbTextCompare
    i = [B:B].Find("*", , xlValues, , xlByRows, xlPrevious).Row
    For Each cl In Range([B2], Cells(i, "B"))
        If Not Dic.exists(cl.Value2) Then
            Dic.Add cl.Value2, "1|" & cl.Offset(, -1).Value2
        Else
            x = Split(Dic(cl.Value2), "|")(0)
            z = x + 1
            Dic(cl.Value2) = Replace(Dic(cl.Value2), x, z) & _
                                    "|" & cl.Offset(, -1).Value2
        End If
    Next cl
    Workbooks.Add
    [A1] = "Room": [B1] = "Count": i = 2
    For Each k In Dic
        Cells(i, "A") = k
        Range(Cells(i, 2), Cells(i, Split(Dic(k), "|")(0) + 2)) = Split(Dic(k), "|")
        i = i + 1
    Next k
End Sub

如何从表中删除所有重复项？

3 个答案: