ForLoop.EvalExpression Eigenschaft

Referenz

Definition

Namespace:: Microsoft.SqlServer.Dts.Runtime

Assembly:: Microsoft.SqlServer.ManagedDTS.dll

Wichtig

Einige Informationen beziehen sich auf Vorabversionen, die vor dem Release ggf. grundlegend überarbeitet werden. Microsoft übernimmt hinsichtlich der hier bereitgestellten Informationen keine Gewährleistungen, seien sie ausdrücklich oder konkludent.

Ruft den Ausdruck ab, der bei jedem Schleifendurchgang ausgewertet wird, oder legt ihn fest.

public:
 property System::String ^ EvalExpression { System::String ^ get(); void set(System::String ^ value); };

[Microsoft.SqlServer.Dts.Runtime.Localization.LocalizablePropertyDescription(typeof(Microsoft.SqlServer.Dts.Runtime.Localized), "EvalExpressionDesc")]
public string EvalExpression { get; set; }

[<Microsoft.SqlServer.Dts.Runtime.Localization.LocalizablePropertyDescription(typeof(Microsoft.SqlServer.Dts.Runtime.Localized), "EvalExpressionDesc")>]
member this.EvalExpression : string with get, set

Public Property EvalExpression As String

Eigenschaftswert

String

Eine Zeichenfolge, die den Ausdruck enthält, der verwendet wird, um zu testen, ob die Schleife die Schleife beenden oder fortsetzen soll.

Attribute: LocalizablePropertyDescriptionAttribute

Beispiele

Im folgenden Codebeispiel wird ein ForLoop erstellt und die drei Ausdruckseigenschaften festgelegt. Enthält ForLoop auch zwei Aufgaben mit einer Rangfolgeneinschränkung.

using System;  
using System.Collections.Generic;  
using System.Text;  
using Microsoft.SqlServer.Dts.Runtime;  
using Microsoft.SqlServer.Dts.Tasks.SendMailTask;  
using Microsoft.SqlServer.Dts.Tasks.BulkInsertTask;  

namespace ForLoopAPI  
{  
    class Program  
    {  
        static void Main(string[] args)  
        {  
            String varName = "MyVariable";  
            int INIT_COUNT = 2;  
            int MAX_COUNT = 5;  

            Package pkg = new Package();  
            Variable var = pkg.Variables.Add(varName, false, "", 0);  
            Variable var2 = pkg.Variables.Add("Counter", false, "", 0);  

            ForLoop forLoop = (ForLoop)pkg.Executables.Add("STOCK:ForLoop");  
            forLoop.InitExpression = "@"+varName+" = "+INIT_COUNT;  
            forLoop.EvalExpression = "@"+varName+" < "+MAX_COUNT;  
            forLoop.AssignExpression = "@" + varName + " = @" + varName + " + " + INIT_COUNT;  

            // Show a different syntax for setting these values.  
            //forLoop.InitExpression = "@Counter = 1";  
            //forLoop.AssignExpression = "@Counter = @Counter + 1";  
            //forLoop.EvalExpression = "@Counter <= 10";  

            // The ForLoop contains a Properties collection.   
           // Show how to set some properties using that collection.  
            forLoop.Properties["Name"].SetValue(forLoop, "ForLoop Container");  
            forLoop.Properties["Description"].SetValue(forLoop, "ForLoop Container");  

            // Review the PackagePath of the ForLoop container.  
            Console.WriteLine("PackagePath: {0}", forLoop.GetPackagePath());  

            // Because the ForLoop is a container, it can contain tasks  
            // that run at certain conditions.  
            TaskHost thLoopMail = (TaskHost)forLoop.Executables.Add("STOCK:SendMailTask");  
            TaskHost thLoopInsert = (TaskHost)forLoop.Executables.Add("STOCK:BulkInsertTask");  
            Executables loopExecs = forLoop.Executables;  
            Console.WriteLine("Number of Executables in ForLoop: {0}", loopExecs.Count);  

            // Like other containers, precedence constraints can be set on the  
            // contained tasks.  
            PrecedenceConstraint pc = forLoop.PrecedenceConstraints.Add((Executable)thLoopMail, thLoopInsert);  
            PrecedenceConstraints pcs = forLoop.PrecedenceConstraints;  
            Console.WriteLine("Number of precedence constraints: {0}", pcs.Count);  

            // Run the package. Because required properties on the tasks are not  
            //  set, current sample code will fail.  
            DTSExecResult result = pkg.Execute();  
        }  
    }  
}

Imports System  
Imports System.Collections.Generic  
Imports System.Text  
Imports Microsoft.SqlServer.Dts.Runtime  
Imports Microsoft.SqlServer.Dts.Tasks.SendMailTask  
Imports Microsoft.SqlServer.Dts.Tasks.BulkInsertTask  

Namespace ForLoopAPI  

   Class Program  

      'Entry point which delegates to C-style main Private Function  
      Public Overloads Shared Sub Main()  
         Main(System.Environment.GetCommandLineArgs())  
      End Sub  

      Overloads Shared Sub Main(args() As String)  
         Dim varName As String = "MyVariable"  
         Dim INIT_COUNT As Integer = 2  
         Dim MAX_COUNT As Integer = 5  

         Dim pkg As New Package()  
         Dim var As Variable = pkg.Variables.Add(varName, False, "", 0)  
         Dim var2 As Variable = pkg.Variables.Add("Counter", False, "", 0)  

         Dim forLoop As ForLoop = CType(pkg.Executables.Add("STOCK:ForLoop"), ForLoop)  
         forLoop.InitExpression = "@" + varName + " = " + INIT_COUNT  
         forLoop.EvalExpression = "@" + varName + " < " + MAX_COUNT  
         forLoop.AssignExpression = "@" + varName + " = @" + varName + " + " + INIT_COUNT  

         ' Show a different syntax for setting these values.  
         forLoop.InitExpression = "@Counter = 1"  
         forLoop.AssignExpression = "@Counter = @Counter + 1"  
         forLoop.EvalExpression = "@Counter <= 10"  
         ' The ForLoop contains a Properties collection.   
         ' Show how to set some properties using that collection.  
         forLoop.Properties("Name").SetValue(forLoop, "ForLoop Container")  
         forLoop.Properties("Description").SetValue(forLoop, "ForLoop Container")  

         ' Review the PackagePath of the ForLoop container.  
         Console.WriteLine("PackagePath: {0}", forLoop.GetPackagePath())  

         ' Because the ForLoop is a container, it can contain tasks  
         ' that run at certain conditions.  
         Dim thLoopMail As TaskHost = CType(forLoop.Executables.Add("STOCK:SendMailTask"), TaskHost)  
         Dim thLoopInsert As TaskHost = CType(forLoop.Executables.Add("STOCK:BulkInsertTask"), TaskHost)  
         Dim loopExecs As Executables = forLoop.Executables  
         Console.WriteLine("Number of Executables in ForLoop: {0}", loopExecs.Count)  

         ' Like other containers, precedence constraints can be set on the  
         ' contained tasks.  
         Dim pc As PrecedenceConstraint = forLoop.PrecedenceConstraints.Add(CType(thLoopMail, Executable), thLoopInsert)  
         Dim pcs As PrecedenceConstraints = forLoop.PrecedenceConstraints  
         Console.WriteLine("Number of precedence constraints: {0}", pcs.Count)  

         ' Run the package. Because required properties on the tasks are not  
         '  set, current sample code will fail.  
         Dim result As DTSExecResult = pkg.Execute()  
      End Sub 'Main  
   End Class 'Program  
End Namespace 'ForLoopAPI

Beispielausgabe:

PackagePath: \Package\{8A18B94E-1176-429E-BB3D-6F3F1E0C9070}

Anzahl ausführbarer Dateien in ForLoop: 2

Anzahl der Rangfolgeneinschränkungen: 1

Hinweise

In jeder Iteration der Schleife wertet der ForLoop Container einen Ausdruck aus und wiederholt seinen Workflow, bis der Ausdruck als falseausgewertet wird.

Gilt für:

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