DataAdapter.Update(DataSet) 方法

定义

从名为“Table”的 DataSet 为指定的 DataTable 中每个已插入、已更新或已删除的行调用相应的 INSERT、UPDATE 或 DELETE 语句。Calls the respective INSERT, UPDATE, or DELETE statements for each inserted, updated, or deleted row in the specified DataSet from a DataTable named "Table."

public:
 virtual int Update(System::Data::DataSet ^ dataSet);
public:
 abstract int Update(System::Data::DataSet ^ dataSet);
public virtual int Update (System.Data.DataSet dataSet);
public abstract int Update (System.Data.DataSet dataSet);
abstract member Update : System.Data.DataSet -> int
override this.Update : System.Data.DataSet -> int
abstract member Update : System.Data.DataSet -> int
Public Overridable Function Update (dataSet As DataSet) As Integer
Public MustOverride Function Update (dataSet As DataSet) As Integer

参数

dataSet
DataSet

用于更新数据源的 DataSetThe DataSet used to update the data source.

返回

Int32

DataSet 中成功更新的行数。The number of rows successfully updated from the DataSet.

实现

例外

源表无效。The source table is invalid.

尝试执行 INSERT、UPDATE 或 DELETE 语句,但没有记录受到影响。An attempt to execute an INSERT, UPDATE, or DELETE statement resulted in zero records affected.

示例

下面的示例使用派生类 OleDbDataAdapterUpdate 数据源。The following example uses the derived class, OleDbDataAdapter, to Update the data source.

static private DataSet CreateCommandAndUpdate(
    string connectionString,
    string queryString)
{
    DataSet dataSet = new DataSet();

    using (OleDbConnection connection =
               new OleDbConnection(connectionString))
    {
        connection.Open();
        OleDbDataAdapter adapter =
            new OleDbDataAdapter();
        adapter.SelectCommand =
            new OleDbCommand(queryString, connection);
        OleDbCommandBuilder builder =
            new OleDbCommandBuilder(adapter);

        adapter.Fill(dataSet);

        // Code to modify data in the DataSet here.

        // Without the OleDbCommandBuilder, this line would fail.
        adapter.UpdateCommand = builder.GetUpdateCommand();
        adapter.Update(dataSet);
    }
    return dataSet;
}
Public Function CreateCommandAndUpdate( _
    ByVal connectionString As String, _
    ByVal queryString As String) As DataSet

    Dim dataSet As New DataSet()

    Using connection As New OleDbConnection(connectionString)
        connection.Open()
        Dim adapter As New OleDbDataAdapter()

        adapter.SelectCommand = New OleDbCommand( _
            queryString, connection)

        Dim builder As OleDbCommandBuilder = _
            New OleDbCommandBuilder(adapter)

        adapter.Fill(dataSet)

        ' Code to modify the data in the DataSet here. 

        ' Without the OleDbCommandBuilder this line would fail.
        builder.GetUpdateCommand()
        adapter.Update(dataSet)
    End Using
    Return dataSet
End Function

注解

更新按行执行。The update is performed on a by-row basis. 对于每个已插入的、已修改的和已删除的行,该 Update 方法将确定对其执行的更改的类型 (Insert、Update 或 Delete) 。For every inserted, modified, and deleted row, the Update method determines the type of change that has been performed on it (Insert, Update or Delete). 根据更改的类型,将 Insert Update, Delete 执行或命令模板,以将修改后的行传播到数据源。Depending on the type of change, the Insert, Update, or Delete command template executes to propagate the modified row to the data source. 当应用程序调用 Update 方法时,将 DataAdapter 检查 RowState 属性,并根据中配置的索引的顺序,对每个行重复执行所需的 INSERT、UPDATE 或 DELETE 语句 DataSetWhen an application calls the Update method, the DataAdapter examines the RowState property, and executes the required INSERT, UPDATE, or DELETE statements iteratively for each row, based on the order of the indexes configured in the DataSet. 例如, Update 可能会执行 DELETE 语句,后跟 INSERT 语句,然后执行另一 delete 语句,因为中的行的顺序 DataTableFor example, Update might execute a DELETE statement, followed by an INSERT statement, and then another DELETE statement, due to the ordering of the rows in the DataTable.

应注意的是,这些语句不作为批处理执行;每一行都单独更新。It should be noted that these statements are not performed as a batch process; each row is updated individually. 应用程序可以 GetChanges 在以下情况下调用方法:在此情况下,必须控制语句类型的序列 (例如,在 UPDATE) 之前插入。An application can call the GetChanges method in situations where you must control the sequence of statement types (for example, INSERT before UPDATE). 有关详细信息,请参阅 用 Dataadapter 更新数据源For more information, see Updating Data Sources with DataAdapters.

如果尚未指定 INSERT、UPDATE 或 DELETE 语句,则该方法将 Update 生成一个异常。If INSERT, UPDATE, or DELETE statements have not been specified, the Update method generates an exception. 但是, SqlCommandBuilder OleDbCommandBuilder 如果您设置了 SelectCommand .NET Framework 数据提供程序的属性,则可以创建或对象以自动为单表更新生成 SQL 语句。However, you can create a SqlCommandBuilder or OleDbCommandBuilder object to automatically generate SQL statements for single-table updates if you set the SelectCommand property of a .NET Framework data provider. 然后, CommandBuilder将生成未设置的任何其他 SQL 语句。Then, any additional SQL statements that you do not set are generated by the CommandBuilder. 此代逻辑要求密钥列信息存在于中 DataSetThis generation logic requires key column information to be present in the DataSet. 有关详细信息,请参阅 通过 Commandbuilder 生成命令For more information see Generating Commands with CommandBuilders.

Update 执行更新之前,方法将从第一个映射中列出的表中检索行。The Update method retrieves rows from the table listed in the first mapping before performing an update. Update然后,使用属性的值刷新该行 UpdatedRowSourceThe Update then refreshes the row using the value of the UpdatedRowSource property. 将忽略返回的任何其他行。Any additional rows returned are ignored.

在将任何数据加载回后 DataSet ,将 OnRowUpdated 引发事件,从而允许用户检查已协调的 DataSet 行和该命令返回的任何输出参数。After any data is loaded back into the DataSet, the OnRowUpdated event is raised, allowing the user to inspect the reconciled DataSet row and any output parameters returned by the command. 成功更新行后,将接受对该行所做的更改。After a row updates successfully, the changes to that row are accepted.

使用时 Update ,执行顺序如下所示:When using Update, the order of execution is as follows:

  1. 中的值 DataRow 将被移动到参数值中。The values in the DataRow are moved to the parameter values.

  2. 引发 OnRowUpdating 事件。The OnRowUpdating event is raised.

  3. 命令执行。The command executes.

  4. 如果命令设置为 FirstReturnedRecord ,则将第一个返回的结果放置在中 DataRowIf the command is set to FirstReturnedRecord, then the first returned result is placed in the DataRow.

  5. 如果有输出参数,则将它们放在中 DataRowIf there are output parameters, they are placed in the DataRow.

  6. 引发 OnRowUpdated 事件。The OnRowUpdated event is raised.

  7. 调用 DataRow.AcceptChangesDataRow.AcceptChanges is called. 这会 DataTable.RowChanging DataTable.RowChanged 为更新后引发和事件 DataRowThis will raise both the DataTable.RowChanging and DataTable.RowChanged events for the updated DataRow.

与关联的每个命令 DataAdapter 通常都具有与之关联的参数集合。Each command associated with the DataAdapter usually has a parameters collection associated with it. 通过 SourceColumn SourceVersion .net 数据提供程序的类的和属性,将参数映射到当前行 ParameterParameters are mapped to the current row through the SourceColumn and SourceVersion properties of a .NET data provider's Parameter class. SourceColumn 引用 DataTable DataAdapter 用于获取当前行的参数值的列。SourceColumn refers to a DataTable column that the DataAdapter references to obtain parameter values for the current row.

SourceColumn 在应用了任何表映射之前引用未映射的列名称。SourceColumn refers to the unmapped column name before any table mappings have been applied. 如果 SourceColumn 引用不存在的列,则执行的操作取决于下列值之一 MissingMappingActionIf SourceColumn refers to a nonexistent column, the action taken depends on one of the following MissingMappingAction values.

枚举值Enumeration value 采取的操作Action taken
MissingMappingAction.Passthrough 如果不存在映射,请使用中的源列名称和表名称 DataSetUse the source column names and table names in the DataSet if no mapping is present.
MissingMappingAction.Ignore SystemException生成。A SystemException is generated. 当显式设置映射时,缺少输入参数的映射通常是由错误引起的。When the mappings are explicitly set, a missing mapping for an input parameter is usually the result of an error.
MissingMappingAction.Error SystemException生成。A SystemException is generated.

SourceColumn属性还可用于将输出或输入/输出参数的值映射回 DataSetThe SourceColumn property is also used to map the value for output or input/output parameters back to the DataSet. 如果引用不存在的列,则会生成异常。An exception is generated if it refers to a nonexistent column.

SourceVersion.Net 数据提供程序的类的属性 Parameter 确定是使用列值的原始版本、当前版本还是建议的版本。The SourceVersion property of a .NET data provider's Parameter class determines whether to use the Original, Current, or Proposed version of the column value. 此功能通常用于在 UPDATE 语句的 WHERE 子句中包含原始值,以检查是否存在开放式并发冲突。This capability is often used to include original values in the WHERE clause of an UPDATE statement to check for optimistic concurrency violations.

调用 AcceptChanges 方法或 AcceptChanges 方法将提交或中的所有更改 DataSet DataTableCalling the AcceptChanges method or AcceptChanges method will commit all changes in the DataSet or DataTable. 如果在调用方法之前调用这些方法中的任何一个 Update ,则调用方法时不会提交任何更改 Update ,除非从或调用以来进行了进一步的更改 AcceptChanges AcceptChangesIf either of these methods are called before the Update method is called, no changes will be committed when the Update method is called, unless further changes have been made since AcceptChanges or AcceptChanges was called.

备注

如果在更新行时出现错误,则会引发异常并中止执行更新。If an error occurs while updating a row, an exception is thrown and execution of the update is discontinued. 若要在遇到错误时继续执行更新操作而不生成异常,请在 ContinueUpdateOnError 调用之前将属性设置为 true UpdateTo continue the update operation without generating exceptions when an error is encountered, set the ContinueUpdateOnError property to true before calling Update. 您还可以在 DataAdapter 事件内每行响应错误 RowUpdatedYou may also respond to errors on a per-row basis within the RowUpdated event of a DataAdapter. 若要继续执行更新操作而不在事件中生成异常 RowUpdated ,请将 Status 的属性设置 RowUpdatedEventArgsContinueTo continue the update operation without generating an exception within the RowUpdated event, set the Status property of the RowUpdatedEventArgs to Continue.

对于传播到上的数据源的每个列 Update ,应将参数添加到 InsertCommandUpdateCommandDeleteCommandFor every column that you propagate to the data source on Update, a parameter should be added to the InsertCommand, UpdateCommand, or DeleteCommand. SourceColumn应将参数的属性设置为列的名称。The SourceColumn property of the parameter should be set to the name of the column. 此设置指示参数的值不是手动设置的,而是从当前处理的行中的特定列获取的。This setting indicates that the value of the parameter is not set manually, but is taken from the particular column in the currently processed row.

适用于

另请参阅