c# - 在 C# 中，我想比较数据表

Question

我想比较两个数据表。我只需要知道 contents 是否不同。谁能推荐一种快速比较它们的方法？

我想知道内容(数据)是否不同

Answer 1

我以为我最近编写的代码遇到了这个问题，但发现我所做的并没有真正起作用。所以我不得不重新审视这个，最近看到了这篇文章。

我之前采用的方法是对内存流都使用 WriteXml 并一次遍历两个 256 个字符的字符串以查找差异。虽然这在大部分时间都有效，但我开始意识到尽管是从同一过程调用的，但我的行和列不一定与其他行和列的顺序相同。

所以我通过比较每一行的哈希码来重新设计它。这让我最终能够比较所有内容，尽管列和行的顺序不同。

首先，我尝试对行数和列数等差异进行一些快速测试，然后确保第一个表中的列存在于第二个表中。如果我们做到了那么远，那么就该使用散列码进行广泛的测试了。我以为它可能需要很长时间才能运行，但结果并没有我想象的那么糟糕。

我知道代码是在 Visual Basic 中，我很抱歉，因为我看到您正在寻找 C#，但我确信转换它很容易。

虽然这个线程很旧，但我希望这段代码可以帮助任何想要做同样事情的人。它肯定胜过逐个单元地检查。

''' <summary>
''' Compares the data between both datatables to check if they have the same content or not.
''' Columns and Rows do not need to be in the same order as the other, just that the data in any of them need to be the same.
''' </summary>
''' <param name="dtbl_a">The first datatable to compare.</param>
''' <param name="dtbl_b">The second datatable to compare.</param>
''' <param name="debug">For troubleshooting and checking the function is working correctly.  Typically this is 'false'.</param>
''' <returns>Boolean:  False if the data between the two datatables are different, True if the data between them are the same.</returns>
''' <remarks></remarks>
Public Function dataTablesAreEqual _
                                  (ByRef dtbl_a As System.Data.DataTable, _
                                   ByRef dtbl_b As System.Data.DataTable, _
                                   ByVal debug As System.Boolean) As System.Boolean

    Dim recordCount(1) As System.Int32
    Dim columnCount(1) As System.Int32
    Dim length(1) As System.Int32
    Dim dtbl_check(1) As System.Data.DataTable
    Dim debugMessage As New System.Text.StringBuilder
    Dim errorMessage As System.String
    Dim result As System.Boolean

    Try
        If debug = True Then
            debugMessage.AppendLine("checking:  priliminary (and easy to see) tests being done...")
            debugMessage.AppendLine("checking:  what is nothing and what is not nothing.")

        End If

        If dtbl_a Is Nothing And dtbl_b Is Nothing Then
            result = True

            If debug = True Then
                debugMessage.AppendLine("decision:  " & result.ToString & "!")
                debugMessage.AppendLine("  reason:  dtbl_a Is Nothing And dtbl_b Is Nothing.")

            End If

            Return result

        ElseIf dtbl_a Is Nothing And dtbl_b IsNot Nothing Then
            result = False

            If debug = True Then
                debugMessage.AppendLine("decision:  " & result.ToString & "!")
                debugMessage.AppendLine("  reason:  dtbl_a Is Nothing And dtbl_b IsNot Nothing.")

            End If

            Return result

        ElseIf dtbl_a IsNot Nothing And dtbl_b Is Nothing Then
            result = False

            If debug = True Then
                debugMessage.AppendLine("decision:  " & result.ToString & "!")
                debugMessage.AppendLine("  reason:  dtbl_a IsNot Nothing And dtbl_b Is Nothing.")

            End If

            Return result

        End If

        If debug = True Then
            debugMessage.AppendLine("checking:  differences in row and column counts.")

        End If

        recordCount(0) = dtbl_a.Rows.Count
        columnCount(0) = dtbl_a.Columns.Count

        recordCount(1) = dtbl_b.Rows.Count
        columnCount(1) = dtbl_b.Columns.Count

        If recordCount(0) <> recordCount(1) Then
            result = False

            If debug = True Then
                debugMessage.AppendLine("decision:  " & result.ToString & "!")
                debugMessage.AppendLine("  reason:  the # of rows are different.")
                debugMessage.AppendLine("  reason:  dtbl_a has " & recordCount(0) & " record(s) and dtbl_b has " & recordCount(1) & " record(s).")

            End If

            Return result

        ElseIf columnCount(0) <> columnCount(1) Then
            result = False

            If debug = True Then
                debugMessage.AppendLine("decision:  " & result.ToString & "!")
                debugMessage.AppendLine("  reason:  the # of columns are different.")
                debugMessage.AppendLine("  reason:  dtbl_a has " & columnCount(0) & " column(s) and dtbl_b has " & columnCount(1) & " column(s).")

            End If

            Return result

        End If

        Dim lowerBound_Records As System.Int32
        Dim upperBound_Records As System.Int32
        Dim current_Record As System.Int32
        Dim lowerBound_Columns As System.Int32
        Dim upperBound_Columns As System.Int32
        Dim current_Column As System.Int32

        lowerBound_Records = 0
        upperBound_Records = (recordCount(0) - 1)
        lowerBound_Columns = 0
        upperBound_Columns = (columnCount(0) - 1)

        If debug = True Then
            debugMessage.AppendLine("checking:  columns exist in both tables (can be in different order).")

        End If

        For current_Column = lowerBound_Columns To upperBound_Columns
            Dim columnName As System.String
            Dim exists As System.Boolean

            columnName = dtbl_a.Columns(current_Column).ColumnName
            exists = dtbl_b.Columns.Contains(columnName)

            If exists = False Then
                result = False

                If debug = True Then
                    debugMessage.AppendLine("decision:  " & result.ToString & "!")
                    debugMessage.AppendLine("  reason:  the column [" & columnName & "] in dtbl_a does NOT EXIST in dtbl_b.")

                End If

                Return result

            End If

        Next current_Column

        dtbl_check(0) = New System.Data.DataTable
        dtbl_check(0).Columns.Add("index", GetType(System.Int32))
        dtbl_check(0).Columns.Add("hashCode", GetType(System.Int32))
        dtbl_check(0).Columns.Add("checked", GetType(System.DateTime))

        If debug = True Then
            dtbl_check(0).Columns.Add("dataRow", GetType(System.String))

        End If

        dtbl_check(0).PrimaryKey = New System.Data.DataColumn() {dtbl_check(0).Columns("index"), dtbl_check(0).Columns("hashCode")}
        dtbl_check(1) = dtbl_check(0).Copy

        If debug = True Then
            debugMessage.AppendLine("checking:  going for the extensive data content check (rows can be in different order).")
            debugMessage.AppendLine("checking:  getting hashcodes from dtbl_a started:  " & System.DateTime.Now.ToString("MM/dd/yyyy hh:mm:ss.ffff"))

        End If

        For current_Record = lowerBound_Records To upperBound_Records
            Dim dataRow_check As New System.Text.StringBuilder

            dataRow_check.Append("<dataRow>")
            For current_Column = lowerBound_Columns To upperBound_Columns
                Dim columnName As System.String
                Dim valueIsNull As System.Boolean
                Dim value As System.String

                columnName = dtbl_a.Columns(current_Column).ColumnName
                valueIsNull = System.Convert.IsDBNull(dtbl_a.Rows(current_Record).Item(columnName))

                If valueIsNull = False Then
                    value = dtbl_a.Rows(current_Record).Item(columnName).ToString

                Else
                    value = "[null]"

                End If

                dataRow_check.Append("<" & columnName & ">" & value & "</" & columnName & ">")

            Next current_Column

            dataRow_check.Append("</dataRow>")

            Dim newRow As System.Data.DataRow = dtbl_check(0).NewRow
            Call newRow.BeginEdit()
            newRow.Item("index") = current_Record
            newRow.Item("hashCode") = dataRow_check.ToString.GetHashCode
            newRow.Item("checked") = System.Convert.DBNull

            If debug = True Then
                newRow.Item("dataRow") = dataRow_check.ToString

            End If

            Call newRow.EndEdit()
            Call dtbl_check(0).Rows.Add(newRow)
            dataRow_check = Nothing

        Next current_Record

        If debug = True Then
            debugMessage.AppendLine("checking:  finished hashcodes for dtbl_a ended:  " & System.DateTime.Now.ToString("MM/dd/yyyy hh:mm:ss.ffff"))
            debugMessage.AppendLine("checking:  getting hashcodes from dtbl_b and cross checking using dtbl_a started:  " & System.DateTime.Now.ToString("MM/dd/yyyy hh:mm:ss.ffff"))

        End If

        For current_Record = lowerBound_Records To upperBound_Records
            Dim dataRow_check As New System.Text.StringBuilder
            Dim checked As System.DateTime

            checked = System.DateTime.Now
            dataRow_check.Append("<dataRow>")

            For current_Column = lowerBound_Columns To upperBound_Columns
                Dim columnName As System.String
                Dim valueIsNull As System.Boolean
                Dim value As System.String

                columnName = dtbl_a.Columns(current_Column).ColumnName

                Try
                    valueIsNull = System.Convert.IsDBNull(dtbl_b.Rows(current_Record).Item(columnName))

                Catch exc As System.Exception
                    result = False
                    Return result

                End Try

                If valueIsNull = False Then
                    value = dtbl_b.Rows(current_Record).Item(columnName).ToString

                Else
                    value = "[null]"

                End If

                dataRow_check.Append("<" & columnName & ">" & value & "</" & columnName & ">")

            Next current_Column

            dataRow_check.Append("</dataRow>")

            Dim selectQuery As System.String
            Dim dataRows() As System.Data.DataRow
            Dim hashCode As System.Int32

            hashCode = dataRow_check.ToString.GetHashCode
            selectQuery = "[hashCode] = " & hashCode.ToString & " and [checked] is null "
            dataRows = dtbl_check(0).Select(selectQuery)

            If dataRows.Length > 0 Then
                Call dataRows(0).BeginEdit()
                dataRows(0).Item("checked") = checked
                Call dataRows(0).EndEdit()

                Dim newRow As System.Data.DataRow = dtbl_check(1).NewRow
                Call newRow.BeginEdit()
                newRow.Item("index") = dataRows(0).Item("index")
                newRow.Item("hashCode") = dataRows(0).Item("hashCode")
                newRow.Item("checked") = checked

                If debug = True Then
                    newRow.Item("dataRow") = dataRow_check.ToString

                End If

                Call newRow.EndEdit()
                Call dtbl_check(1).Rows.Add(newRow)

            Else
                result = False

                If debug = True Then
                    debugMessage.AppendLine("checking:  finished hashcodes for dtbl_b ended:  " & System.DateTime.Now.ToString("MM/dd/yyyy hh:mm:ss.ffff"))
                    debugMessage.AppendLine("decision:  " & result.ToString & "!")
                    debugMessage.AppendLine("  reason:  a row in dtbl_b doesn't match up in dtbl_a (either due to changes or didn't exist).")
                    debugMessage.AppendLine(" dataRow:  " & dataRow_check.ToString)

                End If

                dataRow_check = Nothing

                Return result

            End If

            dataRows = Nothing
            dataRow_check = Nothing

        Next current_Record

        result = True

        If debug = True Then
            debugMessage.AppendLine("checking:  finished hashcodes for dtbl_b ended:  " & System.DateTime.Now.ToString("MM/dd/yyyy hh:mm:ss.ffff"))
            debugMessage.AppendLine("decision:  " & result.ToString & "!")
            debugMessage.AppendLine("  reason:  all " & recordCount(0) & " record(s) match up between both tables.")

        End If

    Catch exc_Exception As System.Exception
        errorMessage = exc_Exception.Message
        result = False

        If debug = True Then
            debugMessage.AppendLine("exception in dataTablesAreEqual!")
            debugMessage.AppendLine("decision:  " & result.ToString & "!")
            debugMessage.AppendLine(" message:  " & errorMessage)

        End If

    Finally
        If dtbl_check(1) IsNot Nothing Then
            Call dtbl_check(1).Clear()
            dtbl_check(1) = Nothing

        End If

        If dtbl_check(0) IsNot Nothing Then
            Call dtbl_check(0).Clear()
            dtbl_check(0) = Nothing

        End If

        If debug = True Then
            Call System.Diagnostics.Debug.WriteLine(debugMessage.ToString)

        End If

        debugMessage = Nothing

    End Try

    Return result

End Function