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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)

public DTSPrecedenceEvalOp EvalOp { get; set; }

Property Value

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

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.

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("-----------------------------------");
            }
        }
    }
}

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

-----------------------------------

Constrained container Microsoft.SqlServer.Dts.Runtime.TaskHost

Creation Name

Description

Evaluation operation Constraint

Evaluates true True

Expression

ID {E8DBC95E-AF27-45D7-B961-17E908CC4530}

LogicalAnd True

Name {E8DBC95E-AF27-45D7-B961-17E908CC4530}

Precedence Executable Microsoft.SqlServer.Dts.Runtime.TaskHost

Value Success

-----------------------------------

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