Question

我已经成功解决了按值here交换行的情况但是通过使用这个功能，我看到拖放行的功能缺乏一些功能我试图获得解决方案错误的解决方案here并提供解决方案是不够的，因为他们需要额外的列。

这是众所周知的表格：

DROP TABLE IF EXISTS kalksad1;

CREATE TABLE kalksad1(
kalk_id     int PRIMARY KEY,
brkalk      integer, 
brred       integer, 
description text);

INSERT INTO kalksad1 VALUES
(12, 2, 5, 'text index 12 doc 2 row 5'),
(26, 2, 1, 'text index 26 doc 2 row 1'),
(30, 2, 2, 'text index 30 doc 2 row 2'),
(32, 4, 1, 'text index 32 doc 4 row 1'),
(36, 1, 1, 'text index 36 doc 1 row 1'),
(37, 1, 2, 'text index 37 doc 1 row 2'),
(38, 5, 1, 'text index 38 doc 5 row 1'),
(39, 5, 2, 'text index 39 doc 5 row 2'),
(42, 2, 3, 'text index 42 doc 2 row 3'),
(43, 2, 4, 'text index 43 doc 2 row 4'),
(46, 3, 1, 'text index 46 doc 3 row 1'),
(47, 3, 2, 'text index 47 doc 3 row 2');

操纵对象是在“brkalk”（doc）下重新排序列“brred”（行）的值。
让“brkalk”为2。

现在我想根据拖放需求进行重新排序/交换，只需交换一行看起来不自然。我有数据网格绑定到kalksad1表，所以我将描述在我的数据网格中查找的情况，其中填充了查询“...由orred by Brred”。

如果我可以通过单词来解释查询... 例1：
在doc 2下，我将拖动第4行并将其放到第2行的位置。
因此需要遵循以下步骤：
1）记住第4行的数据 2）在第3行中，将“brred”的值从3更换为4 3）在第2行中，将“brred”的值从2更换为3 4）在步骤1）的记忆数据中，将“brred”的值从4改为2.

例2：
在doc 2下，我将拖动第1行并将其放到第3位。
这可以是这样的：
1）记住第1行的数据 2）在第2行中，将“brred”的值从2更换为1 3）在第3行中，将“brred”的值从3替换为2 4）在步骤1中记住的数据中，将“brred”的值从1更改为3.

这可能是可能的，因为优雅的解决方案包含交换和SO问题like this，this和this。我根据自己的想法做出了例子，但如果存在更好的话，就不应该这样做。

如果有人可以按照与用户Roman Pekar的swapping类似的方式编写描述的查询。

EDIT: Solution based on Example1 from Tometzky  

Imports Npgsql

Public Class Form1
Dim dServer As String = "127.0.0.1"
Dim dPort As String = "5432"
Dim dUser As String = "postgres"
Dim dPass As String = yourpass
Dim ddatabase As String = yourdatabase
Private dragrect As Rectangle
Private dragindex, dropindex As Integer

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    Dim conn As New NpgsqlConnection(String.Format( _
            "Server={0};Port={1};User Id={2};Password={3};Database={4};", _
             dServer, dPort, dUser, dPass, ddatabase))

    conn.Open()
    Using t As NpgsqlTransaction = conn.BeginTransaction()
        Using cmd As New NpgsqlCommand( _
            "DROP TABLE IF EXISTS kalksad1;", conn)
            cmd.ExecuteNonQuery()
        End Using

        Using cmd As New NpgsqlCommand( _
            "CREATE TABLE kalksad1(" & _
            "kalk_id     int PRIMARY KEY, " & _
            "brkalk      integer, " & _
            "brred       integer, " & _
            "description text);", conn)
            cmd.ExecuteScalar()
        End Using

        Using cmd As New NpgsqlCommand( _
            "INSERT INTO kalksad1 VALUES" & _
            "(12, 2, 5, 'text index 12 doc 2 row 5'), " & _
            "(26, 2, 1, 'text index 26 doc 2 row 1'), " & _
            "(30, 2, 2, 'text index 30 doc 2 row 2'), " & _
            "(32, 4, 1, 'text index 32 doc 4 row 1'), " & _
            "(36, 1, 1, 'text index 36 doc 1 row 1'), " & _
            "(37, 1, 2, 'text index 37 doc 1 row 2'), " & _
            "(38, 5, 1, 'text index 38 doc 5 row 1'), " & _
            "(39, 5, 2, 'text index 39 doc 5 row 2'), " & _
            "(42, 2, 3, 'text index 42 doc 2 row 3'), " & _
            "(43, 2, 4, 'text index 43 doc 2 row 4'), " & _
            "(46, 3, 1, 'text index 46 doc 3 row 1'), " & _
            "(47, 3, 2, 'text index 47 doc 3 row 2');", conn)
            cmd.ExecuteNonQuery()
        End Using
        t.Commit()
    End Using

    With DataGridView1
        .AllowDrop = True
        .MultiSelect = False
        .Dock = DockStyle.Fill
        .SelectionMode = DataGridViewSelectionMode.FullRowSelect
        .AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.AllCells
        .Columns.Add("col1", "ID")
        .Columns.Add("col2", "Doc")
        .Columns.Add("col3", "Row")
        .Columns.Add("col4", "Description")
    End With

    FillData(0)
End Sub

Private Sub FillData(ByVal dropindex As Integer)

    DataGridView1.Rows.Clear()

    Try
        Using mCon As New NpgsqlConnection(String.Format( _
                      "Server={0};Port={1};User Id={2};Password={3};Database={4};", _
                      dServer, dPort, dUser, dPass, ddatabase))

            mCon.Open()
            Using mCmd = New NpgsqlCommand( _
                      "SELECT kalk_id, brkalk, brred, description " & _
                      "FROM kalksad1 " & _
                      "WHERE brkalk='2' ORDER BY brred", mCon)

                Using reader As NpgsqlDataReader = mCmd.ExecuteReader()
                    While (reader.Read())
                        DataGridView1.Rows.Add(New String() _
                        {CStr(reader("kalk_id")), _
                         CStr(reader("brkalk")), _
                         CStr(reader("brred")), _
                         CStr(reader("description"))})
                    End While
                End Using
            End Using
        End Using
    Catch ex As Exception
        Debug.Print(ex.Message)
    End Try

    ''selecting a row
    If dropindex < 0 Then dropindex = 0
    With DataGridView1
        .Rows(dropindex).Selected = True
        .CurrentCell = .Item(0, dropindex)
    End With
End Sub

#Region "dragdrop"
Private Sub DataGridView1_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles DataGridView1.DragDrop
    Dim p As Point = Me.PointToClient(New Point(e.X, e.Y))
    dropindex = DataGridView1.HitTest(p.X, p.Y).RowIndex

    If (e.Effect = DragDropEffects.Move) Then
        Dim dragRow As DataGridViewRow = CType(e.Data.GetData(GetType(DataGridViewRow)), DataGridViewRow)

        Dim _from As Integer = dragindex + 1 ''grid is zero based, document is 1 based
        Dim _to As Integer = dropindex + 1

        Dim updown As String = ""
        If _from < _to Then    ''correction for up
            _to = _to + 1
            updown = "!"
        End If

        '' PROCEDURE HERE -----------------------------------------------------------------
        Dim affected As Integer = 0
        Try
            Using conn As New NpgsqlConnection(String.Format( _
                          "Server={0};Port={1};User Id={2};Password={3};Database={4};", _
                          dServer, dPort, dUser, dPass, ddatabase))

                conn.Open()
                Using t As NpgsqlTransaction = conn.BeginTransaction()
                    Using cmd As New NpgsqlCommand( _
                          "UPDATE kalksad1 SET brred=_brred " & _
                              "FROM (" & _
                              "  SELECT " & _
                              "    row_number() OVER (" & _
                              "      ORDER BY brred<" & _to.ToString & " DESC, brred" & updown & "=" & _from.ToString & " DESC, brred>=" & _to.ToString & " DESC, brred" & _
                              "    ) AS _brred," & _
                              "    kalk_id AS _kalk_id " & _
                              "FROM kalksad1 " & _
                              "WHERE brkalk=2 " & _
                              "ORDER BY _kalk_id" & _
                              ") AS _ " & _
                              "WHERE kalk_id=_kalk_id AND brred!=_brred;", conn)

                        affected = CInt(cmd.ExecuteNonQuery())
                    End Using
                    If affected > 0 Then t.Commit()
                End Using
            End Using
        Catch ex As Exception
            Debug.Print(ex.Message)
        End Try
        ''---------------------------------------------------------------------------------
        FillData(dropindex) ''clear, fill and select dropped row
    End If
End Sub

Private Sub DataGridView1_DragOver(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles DataGridView1.DragOver
    e.Effect = DragDropEffects.Move
End Sub

Private Sub DataGridView1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles DataGridView1.MouseDown

    dragindex = DataGridView1.HitTest(e.X, e.Y).RowIndex
    If dragindex > -1 Then
        Dim dragSize As Size = SystemInformation.DragSize
        dragrect = New Rectangle(New Point(CInt(e.X - (dragSize.Width / 2)), CInt(e.Y - (dragSize.Height / 2))), dragSize)
    Else
        dragrect = Rectangle.Empty
    End If
End Sub

Private Sub DataGridView1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles DataGridView1.MouseMove

    If (e.Button And MouseButtons.Left) = MouseButtons.Left Then
        If (dragrect <> Rectangle.Empty AndAlso Not dragrect.Contains(e.X, e.Y)) Then
            Me.DoDragDrop(DataGridView1.Rows(dragindex), DragDropEffects.Move)
        End If
    End If
End Sub
#End Region

End Class

Answer 1

示例1：

update kalksad1 set brred=_brred
from (
  select
    row_number() over (
      order by brred<2 desc, brred=4 desc, brred>=2 desc, brred
    ) as _brred,
    kalk_id as _kalk_id
  from kalksad1
  where brkalk=2
  order by _kalk_id
) as _
where kalk_id=_kalk_id and brred!=_brred;

示例2：

update kalksad1 set brred=_brred
from (
  select
    row_number() over (
      order by brred<4 desc, brred!=1 desc, brred>=4 desc, brred
    ) as _brred,
    kalk_id as _kalk_id
  from kalksad1
  where brkalk=2
  order by _kalk_id
) as _
where kalk_id=_kalk_id and brred!=_brred;

如果您在(brkalk,brred)上有唯一索引，则会更复杂，因为在重新编号期间会有重复的brred。

但是对于很多行，我建议使用在8位计算机上使用BASIC语言时非常有用的东西 - 用差距对行进行编号。

所以而不是：

(26, 2, 1, 'text index 26 doc 2 row 1'),
(30, 2, 2, 'text index 30 doc 2 row 2'),
(42, 2, 3, 'text index 42 doc 2 row 3'),
(43, 2, 4, 'text index 43 doc 2 row 4'),
(12, 2, 5, 'text index 12 doc 2 row 5'),

使用：

(26, 2, 1024, 'text index 26 doc 2 row 1'),
(30, 2, 2048, 'text index 30 doc 2 row 2'),
(42, 2, 3072, 'text index 42 doc 2 row 3'),
(43, 2, 4096, 'text index 43 doc 2 row 4'),
(12, 2, 5120, 'text index 12 doc 2 row 5'),

然后你的例子就像：

示例1：update kalksad1 set brred=(2048+1024)/2 where kalk_id=43，将其更改为：

(26, 2, 1024, 'text index 26 doc 2 row 1'),
(43, 2, 1536, 'text index 43 doc 2 row 4'),
(30, 2, 2048, 'text index 30 doc 2 row 2'),
(42, 2, 3072, 'text index 42 doc 2 row 3'),
(12, 2, 5120, 'text index 12 doc 2 row 5'),

示例2：update kalksad1 set brred=(4096+3072)/2 where kalk_id=43，将其更改为：

(30, 2, 2048, 'text index 30 doc 2 row 2'),
(42, 2, 3072, 'text index 42 doc 2 row 3'),
(26, 2, 3584, 'text index 26 doc 2 row 1'),
(43, 2, 4096, 'text index 43 doc 2 row 4'),
(12, 2, 5120, 'text index 12 doc 2 row 5'),

只有当目标应该在的行之间没有间隙时，您才需要首先使用例如重新编号行：

update kalksad1 set brred=_brred*1024
from (
  select row_number() over (order by brred) as _brred, kalk_id as _kalk_id
  from kalksad1
  where brkalk=2
  order by _brred desc
) as _
where kalk_id=_kalk_id;

这比改变源和目标之间的每一行要多得多。但这只会在可能有很多行要改变时才会发生。

Answer 2

它通过一组触发器+相关函数来处理Tab键顺序。

更新特定brred的{{1}}会导致旧值和新值之间的所有值旋转，无论是向上还是向下。
DELETE将导致OLD值之上的所有brkalk值（对于相同的brred）递减（向下移动）
INSERT会导致所有brkalk值高于NEW值（对于相同的brred）递增（向上移动）

为了避免永久递归更新，每行需要额外的一些信息：brkalk（应该只触发触发器，不是应用程序代码。它可以通过视图隐藏应用程序

flipflag

结果：

ALTER TABLE kalksad1 ADD COLUMN flipflag boolean DEFAULT false;

        -- This should be an UNIQUE constraint
        -- , but that would need to be deferrable.
CREATE INDEX ON kalksad1 (brkalk,brred);


        -- Trigger functions for Insert/update/delete
CREATE function rotate_brred()
RETURNS TRIGGER AS $body$

BEGIN
        UPDATE kalksad1 fr
        SET brred = brred +1
        , flipflag = NOT flipflag       -- alternating bit protocol ;-)
        WHERE NEW.brred < OLD.brred
        -- AND OLD.flipflag = NEW.flipflag -- redundant condition
        -- AND OLD.brkalk = NEW.brkalk
        AND fr.brkalk = NEW.brkalk
        AND fr.brred >= NEW.brred
        AND fr.brred < OLD.brred
        AND fr.kalk_id <> NEW.kalk_id             -- exlude the initiating row
                ;
        UPDATE kalksad1 fr
        SET brred = brred -1
        , flipflag = NOT flipflag
        WHERE NEW.brred > OLD.brred
        -- AND OLD.flipflag = NEW.flipflag
        -- AND OLD.brkalk = NEW.brkalk
        AND fr.brkalk = NEW.brkalk
        AND fr.brred <= NEW.brred
        AND fr.brred > OLD.brred
        AND fr.kalk_id <> NEW.kalk_id
        ;
        RETURN NEW;
END;

$body$
language plpgsql;

CREATE function shift_down()
RETURNS TRIGGER AS $body$

BEGIN

        UPDATE kalksad1 fr
        SET brred = brred -1
        , flipflag = NOT flipflag       -- alternating bit protocol ;-)
        WHERE fr.brred > OLD.brred
        AND fr.brkalk = OLD.brkalk
                ;
        RETURN NEW;
END;

$body$
language plpgsql;

CREATE function shift_up()
RETURNS TRIGGER AS $body$

BEGIN
        UPDATE kalksad1 fr
        SET brred = brred +1
        , flipflag = NOT flipflag       -- alternating bit protocol ;-)
        WHERE fr.brred >= NEW.brred
        AND fr.brkalk = NEW.brkalk
                ;
        RETURN NEW;
END;

$body$
language plpgsql;


        -- Triggers for Insert/Update/Delete
        -- ONLY for the case where brkalk is NOT CHANGED
CREATE TRIGGER shift_brred_u
        AFTER UPDATE OF brred ON kalksad1
        FOR EACH ROW
        WHEN (OLD.flipflag = NEW.flipflag AND OLD.brkalk = NEW.brkalk AND OLD.brred <> NEW.brred)
        EXECUTE PROCEDURE rotate_brred()
        ;
CREATE TRIGGER shift_brred_d
        AFTER DELETE ON kalksad1
        FOR EACH ROW
        EXECUTE PROCEDURE shift_down()
        ;
CREATE TRIGGER shift_brred_i
        BEFORE INSERT ON kalksad1
        FOR EACH ROW
        EXECUTE PROCEDURE shift_up()
        ;

        -- Test it
UPDATE kalksad1
SET brred = 2
WHERE brkalk = 2
AND brred = 4;

SELECT * FROM kalksad1
ORDER BY brkalk, brred;

PostgreSQL，拖动和交换

2 个答案: