Свойство PrecedenceConstraints

Синтаксис

'Декларация
Public ReadOnly Property PrecedenceConstraints As PrecedenceConstraints
    Get
'Применение
Dim instance As ForEachLoop
Dim value As PrecedenceConstraints

value = instance.PrecedenceConstraints

public PrecedenceConstraints PrecedenceConstraints { get; }

public:
virtual property PrecedenceConstraints^ PrecedenceConstraints {
    PrecedenceConstraints^ get () sealed;
}

abstract PrecedenceConstraints : PrecedenceConstraints
override PrecedenceConstraints : PrecedenceConstraints

final function get PrecedenceConstraints () : PrecedenceConstraints

Реализует интерфейс

IDTSSequence. . :: . .PrecedenceConstraints

Замечания

The order of execution of the objects in the collection is determined by the PrecedenceConstraints added to the container. PrecedenceConstraints allow execution branching based on the success, failure, or completion of an executable in the collection.

Примеры

The following code example creates a ForEachLoop and sets some properties using the Properties collection. Two tasks are added to the Executables collection, and a precedence constraint is put between them.

// Create the package.
Package package = new Package();
// Add variables.
package.Variables.Add("Id", false, "User", 0);

// Create ForEachLoop task
Executables executables = package.Executables;
ForEachLoop forEachLoop = executables.Add("STOCK:FOREACHLOOP") as ForEachLoop;

// The ForEachLoop is a container. Add some task executables and
// create a precedence constraint. The tasks can run when
// certain conditions in the loop are met.
TaskHost thLoopMail = (TaskHost)forEachLoop.Executables.Add("STOCK:SendMailTask");
TaskHost thLoopInsert = (TaskHost)forEachLoop.Executables.Add("STOCK:BulkInsertTask");
Executables loopExecs = forEachLoop.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 = forEachLoop.PrecedenceConstraints.Add((Executable)thLoopMail, thLoopInsert);
PrecedenceConstraints pcs = forEachLoop.PrecedenceConstraints;
Console.WriteLine("Number of precedence constraints: {0}", pcs.Count);

' Create the package.
Dim package As Package =  New Package() 
' Add variables.
package.Variables.Add("Id", False, "User", 0)
 
' Create ForEachLoop task
Dim executables As Executables =  package.Executables 
Dim forEachLoop As ForEachLoop =  executables.Add("STOCK:FOREACHLOOP") as ForEachLoop 
 
' The ForEachLoop is a container. Add some task executables and
' create a precedence constraint. The tasks can run when
' certain conditions in the loop are met.
Dim thLoopMail As TaskHost = CType(forEachLoop.Executables.Add("STOCK:SendMailTask"), TaskHost)
Dim thLoopInsert As TaskHost = CType(forEachLoop.Executables.Add("STOCK:BulkInsertTask"), TaskHost)
Dim loopExecs As Executables =  forEachLoop.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 =  forEachLoop.PrecedenceConstraints.Add(CType(thLoopMail,thLoopInsert, Executable)) 
Dim pcs As PrecedenceConstraints =  forEachLoop.PrecedenceConstraints 
Console.WriteLine("Number of precedence constraints: {0}", pcs.Count)

Sample Output:

Number of Executables in ForLoop: 2

Number of precedence constraints: 1

См. также

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