ForEachLoop.PrecedenceConstraints 属性
定义
重要
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返回包含与 PrecedenceConstraints 关联的所有优先约束的 ForEachLoop 集合。
public:
property Microsoft::SqlServer::Dts::Runtime::PrecedenceConstraints ^ PrecedenceConstraints { Microsoft::SqlServer::Dts::Runtime::PrecedenceConstraints ^ get(); };public Microsoft.SqlServer.Dts.Runtime.PrecedenceConstraints PrecedenceConstraints { get; }member this.PrecedenceConstraints : Microsoft.SqlServer.Dts.Runtime.PrecedenceConstraintsPublic ReadOnly Property PrecedenceConstraints As PrecedenceConstraints属性值
一个 PrecedenceConstraints 集合。
实现
示例
下面的代码示例使用Properties集合创建ForEachLoop并设置一些属性。 将两个任务添加到 Executables 集合中，并在它们之间放置优先约束。
// 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)
示例输出：
ForLoop 中的可执行文件数：2
优先约束数：1
注解
集合中对象的执行顺序由 PrecedenceConstraints 添加到容器中确定。 PrecedenceConstraints 允许基于集合中可执行文件的成功、失败或完成执行分支。