Artikel
05/23/2011

PrecedenceConstraint.EvalOp Property

Gets or sets the evaluation operations used by the precedence constraint.

Namespace: Microsoft.SqlServer.Dts.Runtime
Assembly: Microsoft.SqlServer.ManagedDTS (in Microsoft.SqlServer.ManagedDTS.dll)

Syntax

'Declaration
Public Property EvalOp As DTSPrecedenceEvalOp
    Get
    Set
'Usage
Dim instance As PrecedenceConstraint
Dim value As DTSPrecedenceEvalOp

value = instance.EvalOp

instance.EvalOp = value

public DTSPrecedenceEvalOp EvalOp { get; set; }

public:
property DTSPrecedenceEvalOp EvalOp {
    DTSPrecedenceEvalOp get ();
    void set (DTSPrecedenceEvalOp value);
}

member EvalOp : DTSPrecedenceEvalOp with get, set

function get EvalOp () : DTSPrecedenceEvalOp
function set EvalOp (value : DTSPrecedenceEvalOp)

Property Value

Type: Microsoft.SqlServer.Dts.Runtime.DTSPrecedenceEvalOp
A value from the DTSPrecedenceEvalOp enumeration.

Remarks

The values in the enumeration

A precedence constraint links two executables: the precedence executable and the constrained executable. The precedence executable runs before the constrained executable, and the execution result of the precedence executable may determine whether the constrained executable runs. Whether or not the execution result of the precedence executable determines if the constrained executable runs is dependent on this property setting.

Examples

The following code example creates three tasks, and connects them by using precedence constraints. The sample then iterates over the constraints in the PrecedenceConstraints collection of the package, printing information about each constraint.

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.SqlServer.Dts.Runtime;

namespace PrecedenceConst
{
    class Program
    {
        static void Main(string[] args)
        {
            Package pkg = new Package();
            // Add a File System task.
            Executable eFileTask1 = pkg.Executables.Add("STOCK:FileSystemTask");
            TaskHost thFileTask1 = eFileTask1 as TaskHost;

            // Add a second File System task.
            Executable eFileTask2 = pkg.Executables.Add("STOCK:FileSystemTask");
            TaskHost thFileTask2 = eFileTask2 as TaskHost;

            // Add a Bulk Insert task.
            Executable eBulkInsert = pkg.Executables.Add("STOCK:BulkInsertTask");
            TaskHost thBulkInsert = eBulkInsert as TaskHost;

            // Add a precedence contraint between eFileTask1 and eFileTask2.
            // Set the constraint to be that eFileTask2 cannot run 
            // until eFileTask1 completes.
            PrecedenceConstraint pcFileTasks = pkg.PrecedenceConstraints.Add(eFileTask1, eFileTask2);

            // Add another precedence contraint. Add it between eFileTask2 and BulkInsert.
            // Again, set the constraint to be that BulkInsert cannot run 
            // until eFileTask2 completes.
            PrecedenceConstraint pcFiletoBulk = pkg.PrecedenceConstraints.Add(eFileTask2, eBulkInsert);

            // Obtain the precedence constraint collection, and display properties.
            // Some properties are read/write and have not been set.
            PrecedenceConstraints pConsts = pkg.PrecedenceConstraints;
            foreach (PrecedenceConstraint pc in pConsts)
            {
                Console.WriteLine("Constrained container  {0}", pc.ConstrainedExecutable);
                Console.WriteLine("Creation Name          {0}", pc.CreationName);
                Console.WriteLine("Description            {0}", pc.Description);
                Console.WriteLine("Evaluation operation   {0}", pc.EvalOp);
                Console.WriteLine("Evaluates true         {0}", pc.EvaluatesTrue);
                Console.WriteLine("Expression             {0}", pc.Expression);
                Console.WriteLine("ID                     {0}", pc.ID);
                Console.WriteLine("LogicalAnd             {0}", pc.LogicalAnd);
                Console.WriteLine("Name                   {0}", pc.Name);
                Console.WriteLine("Precedence Executable  {0}", pc.PrecedenceExecutable);
                Console.WriteLine("Value                  {0}", pc.Value);
                Console.WriteLine("-----------------------------------");
            }
        }
    }
}

Imports System
Imports System.Collections.Generic
Imports System.Text
Imports Microsoft.SqlServer.Dts.Runtime
 
Namespace PrecedenceConst
    Class Program
        Shared  Sub Main(ByVal args() As String)
            Dim pkg As Package =  New Package() 
            ' Add a File System task.
            Dim eFileTask1 As Executable =  pkg.Executables.Add("STOCK:FileSystemTask") 
            Dim thFileTask1 As TaskHost =  eFileTask1 as TaskHost 
 
            ' Add a second File System task.
            Dim eFileTask2 As Executable =  pkg.Executables.Add("STOCK:FileSystemTask") 
            Dim thFileTask2 As TaskHost =  eFileTask2 as TaskHost 
 
            ' Add a Bulk Insert task.
            Dim eBulkInsert As Executable =  pkg.Executables.Add("STOCK:BulkInsertTask") 
            Dim thBulkInsert As TaskHost =  eBulkInsert as TaskHost 
 
            ' Add a precedence contraint between eFileTask1 and eFileTask2.
            ' Set the constraint to be that eFileTask2 cannot run 
            ' until eFileTask1 completes.
            Dim pcFileTasks As PrecedenceConstraint =  pkg.PrecedenceConstraints.Add(eFileTask1,eFileTask2) 
 
            ' Add another precedence contraint. Add it between eFileTask2 and BulkInsert.
            ' Again, set the constraint to be that BulkInsert cannot run 
            ' until eFileTask2 completes.
            Dim pcFiletoBulk As PrecedenceConstraint =  pkg.PrecedenceConstraints.Add(eFileTask2,eBulkInsert) 
 
            ' Obtain the precedence constraint collection, and display properties.
            ' Some properties are read/write and have not been set.
            Dim pConsts As PrecedenceConstraints =  pkg.PrecedenceConstraints 
            Dim pc As PrecedenceConstraint
            For Each pc In pConsts
                Console.WriteLine("Constrained container  {0}", pc.ConstrainedExecutable)
                Console.WriteLine("Creation Name          {0}", pc.CreationName)
                Console.WriteLine("Description            {0}", pc.Description)
                Console.WriteLine("Evaluation operation   {0}", pc.EvalOp)
                Console.WriteLine("Evaluates true         {0}", pc.EvaluatesTrue)
                Console.WriteLine("Expression             {0}", pc.Expression)
                Console.WriteLine("ID                     {0}", pc.ID)
                Console.WriteLine("LogicalAnd             {0}", pc.LogicalAnd)
                Console.WriteLine("Name                   {0}", pc.Name)
                Console.WriteLine("Precedence Executable  {0}", pc.PrecedenceExecutable)
                Console.WriteLine("Value                  {0}", pc.Value)
                Console.WriteLine("-----------------------------------")
            Next
        End Sub
    End Class
End Namespace

Sample Output:

Constrained container Microsoft.SqlServer.Dts.Runtime.TaskHost

Creation Name

Description

Evaluation operation Constraint

Evaluates true True

Expression

ID {BA20A288-545D-4E48-864A-E6AF6C3B9AEE}

LogicalAnd True

Name {BA20A288-545D-4E48-864A-E6AF6C3B9AEE}

Precedence Executable Microsoft.SqlServer.Dts.Runtime.TaskHost

Value Success

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