DTSPrecedenceEvalOp 枚举

定义

命名空间:

Microsoft.SqlServer.Dts.Runtime

程序集:

Microsoft.SqlServer.ManagedDTS.dll

指示优先约束使用的求值运算。

public enum class DTSPrecedenceEvalOp

public enum DTSPrecedenceEvalOp

type DTSPrecedenceEvalOp = 

Public Enum DTSPrecedenceEvalOp

继承

Enum

DTSPrecedenceEvalOp

字段

Constraint	2	指定执行结果确定受约束的容器或任务是否运行。 请将 Value 的 PrecedenceConstraint 属性设置为 DTSExecResult 枚举中的所需值。
Expression	1	指定表达式的值确定受约束的容器或任务是否运行。 请设置 Expression 的 PrecedenceConstraint 属性。
ExpressionAndConstraint	3	指定约束结果必须发生且表达式必须计算，受约束的容器或任务才能运行。 设置属性 Value 和 Expression 属性 PrecedenceConstraint，并将其 LogicalAnd 属性设置为 true。
ExpressionOrConstraint	4	指定约束结果必须发生，或者表达式必须计算，受约束的容器或任务才能运行。 设置属性 Value 和 Expression 属性 PrecedenceConstraint，并将其 LogicalAnd 属性设置为 false。

示例

下面的代码示例创建三个任务，并在它们之间放置优先约束。 PrecedenceConstraints使用集合，循环访问包中的约束，显示有关每个约束的信息，包括属性，其中包含EvalOp此枚举中的值之一。 然后，代码示例更改使用此枚举的值 EvalOp 。

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

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);  
            pcFileTasks.Name = "constraint between File System Tasks";  

            // 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);  
            pcFileTasks.Name = "constraint between File System and Bulk Insert Tasks";  

            // Obtain the precedence constraint collection.  
            PrecedenceConstraints pConsts = pkg.PrecedenceConstraints;  
            Boolean containsConstraint = pkg.PrecedenceConstraints.Contains("constraint between File System and Bulk Insert Tasks");  
            Console.WriteLine("Contains the constraint between File System and Bulk Insert Tasks? {0}", containsConstraint);  

            foreach (PrecedenceConstraint pc in pConsts)  
            {  
                Console.WriteLine("Constrained container  {0}", pc.ConstrainedExecutable);  
                Console.WriteLine("Evaluation operation   {0}", pc.EvalOp);  
                Console.WriteLine("Evaluates true         {0}", pc.EvaluatesTrue);  
                Console.WriteLine("ID                     {0}", pc.ID);  
                Console.WriteLine("LogicalAnd             {0}", pc.LogicalAnd);  
                Console.WriteLine("Precedence Executable  {0}", pc.PrecedenceExecutable);  
                Console.WriteLine("-----------------------------------");  
            }  

            // Set the EvalOp of the first constraint using the DtsPrecedenceEvalOp enumerator.  
            PrecedenceConstraint firstPC = pConsts[0];  
            firstPC.EvalOp = DTSPrecedenceEvalOp.Expression;  
            Console.WriteLine("Evaluation operation after {0}", firstPC.EvalOp);  
        }  
    }  
}  

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

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)   
            pcFileTasks.Name = "constraint between File System Tasks"  

            ' 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)   
            pcFileTasks.Name = "constraint between File System and Bulk Insert Tasks"  

            ' Obtain the precedence constraint collection.  
            Dim pConsts As PrecedenceConstraints =  pkg.PrecedenceConstraints   
            Dim containsConstraint As Boolean =  pkg.PrecedenceConstraints.Contains("constraint between File System and Bulk Insert Tasks")   
            Console.WriteLine("Contains the constraint between File System and Bulk Insert Tasks? {0}", containsConstraint)  

            Dim pc As PrecedenceConstraint  
            For Each pc In pConsts  
                Console.WriteLine("Constrained container  {0}", pc.ConstrainedExecutable)  
                Console.WriteLine("Evaluation operation   {0}", pc.EvalOp)  
                Console.WriteLine("Evaluates true         {0}", pc.EvaluatesTrue)  
                Console.WriteLine("ID                     {0}", pc.ID)  
                Console.WriteLine("LogicalAnd             {0}", pc.LogicalAnd)  
                Console.WriteLine("Precedence Executable  {0}", pc.PrecedenceExecutable)  
                Console.WriteLine("-----------------------------------")  
            Next  

            ' Set the EvalOp of the first constraint using the DtsPrecedenceEvalOp enumerator.  
            Dim firstPC As PrecedenceConstraint =  pConsts(0)   
            firstPC.EvalOp = DTSPrecedenceEvalOp.Expression  
            Console.WriteLine("Evaluation operation after {0}", firstPC.EvalOp)  
        End Sub  
    End Class  
End Namespace  

示例输出：

Contains the constraint between File System and Bulk Insert Tasks? True

Constrained container Microsoft.SqlServer.Dts.Runtime.TaskHost

Evaluation operation Constraint

Evaluates true True

ID {0EDDD5B8-7135-4A73-B240-EDF54C0E66AC}

LogicalAnd True

Precedence Executable Microsoft.SqlServer.Dts.Runtime.TaskHost

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

Constrained container Microsoft.SqlServer.Dts.Runtime.TaskHost

Evaluation operation Constraint

Evaluates true True

ID {80584B94-A3D0-4E08-B9C1-8CCC7BD7D086}

LogicalAnd True

Precedence Executable Microsoft.SqlServer.Dts.Runtime.TaskHost

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

Evaluation operation after Expression

注解

优先项是任务或容器，其表达式或执行结果 (完成、成功或失败) 确定下一个任务或容器（约束项）是否运行。 默认值为 Constraint。 有关详细信息，请参阅 优先约束。