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

参数

dataSet
DataSet

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

返回

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

实现

异常

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. 对于每个插入行、已修改行和已删除行,Update 方法将确定对其执行的更改类型(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,将执行 InsertUpdate,Delete 命令模板,以将已修改的行传播到数据源。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,DataAdapter 将检查 RowState 属性,并根据在 DataSet中配置的索引的顺序对每个行执行所需的 INSERT、UPDATE 或 DELETE 语句。When 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 DataTable中的行的顺序。For 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. 如果必须控制语句类型的顺序(例如,在 UPDATE 之前插入),则应用程序可以调用 GetChanges 方法。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,Update 方法将生成一个异常。If INSERT, UPDATE, or DELETE statements have not been specified, the Update method generates an exception. 不过,如果设置 .NET Framework 数据提供程序的 SelectCommand 属性,则可以创建 SqlCommandBuilderOleDbCommandBuilder 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 DataSet中。This 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.

在执行更新之前,Update 方法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. 然后,Update 使用 UpdatedRowSource 属性的值刷新该行。The 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.

将任何数据加载回 DataSet后,将引发 OnRowUpdated 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 Update时,执行顺序如下所示:When using Update, the order of execution is as follows:

  1. DataRow 中的值将移至参数值。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 DataRow中。If the command is set to FirstReturnedRecord, then the first returned result is placed in the DataRow.

  5. 如果有输出参数,它们会置于 DataRow中。If 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. 这将引发更新 DataRowDataTable.RowChangingDataTable.RowChanged 事件。This will raise both the DataTable.RowChanging and DataTable.RowChanged events for the updated DataRow.

DataAdapter 关联的每个命令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. 参数通过 .NET 数据提供程序的 Parameter 类的 SourceColumnSourceVersion 属性映射到当前行。Parameters are mapped to the current row through the SourceColumn and SourceVersion properties of a .NET data provider's Parameter class. SourceColumnDataAdapter 为获取当前行的参数值而引用的 DataTable 列。SourceColumn refers to a DataTable column that the DataAdapter references to obtain parameter values for the current row.

在应用任何表映射之前,SourceColumn 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 MissingMappingAction 值之一。If SourceColumn refers to a nonexistent column, the action taken depends on one of the following MissingMappingAction values.

枚举值Enumeration value 执行的操作Action taken
MissingMappingAction.Passthrough 如果不存在任何映射,请使用 DataSet 中的源列名称和表名称。Use the source column names and table names in the DataSet if no mapping is present.
MissingMappingAction.Ignore 生成一个 SystemExceptionA 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 生成一个 SystemExceptionA SystemException is generated.

SourceColumn 属性还用于将输出或输入/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.

.NET 数据提供程序的 Parameter 类的 SourceVersion 属性确定是否使用列值的原始版本、当前版本或建议版本。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 DataSetDataTable中的所有更改。Calling the AcceptChanges method or AcceptChanges method will commit all changes in the DataSet or DataTable. 如果在调用 Update 方法之前调用这两个方法中的任何一个,则调用 Update 方法时不会提交任何更改,除非从 AcceptChangesAcceptChanges 调用以来进行了进一步的更改。If 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,请在调用 Update之前将 ContinueUpdateOnError 属性设置为 trueTo 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 的 RowUpdated 事件内每行响应错误。You may also respond to errors on a per-row basis within the RowUpdated event of a DataAdapter. 若要在 RowUpdated 事件中继续执行更新操作而不生成异常,请将 RowUpdatedEventArgsStatus 属性设置为 "Continue"。To 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 Update上的数据源的每个列,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. 应将参数的 SourceColumn 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