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The DataContext object manages object identity for you so that rows retrieved from the database table are automatically logged in the DataContext object’s internal identity table by the row’s primary key when the object is created. If the same row is retrieved again by this DataContext object, the o 阅读全文
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Transactions have four essential attributes: atomicity, consistency, isolation, and durability (known as the ACID attributes). ■ Atomicity The work cannot be broken into smaller parts. Although... 阅读全文
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When DbDataAdapter is used to retrieve or update data, it examines the status of the con- nection. If the connection is open, the DbDataAdapter uses the open connection and leaves the connection... 阅读全文
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A DbDataReader object provides a high-performance method of retrieving data from the data store. It delivers a forward-only, read-only, server-side cursor. This makes the DbDataReader object a... 阅读全文
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It’s common practice to store connection strings in the Web.config file. This makes it easy to change the connection string without requiring a recompile of the application. However, connec-tion strings can contain logon information such as user names and passwords. You certainly don’t want this inf 阅读全文
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EXAM TIPRemember for the exam that setting the RemotingFormat property to SerializationFormat.Binary is required to obtain true binary serialization. 阅读全文
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//read xml file into datasetDataSet vendorData = new DataSet(); vendorData.ReadXmlSchema(desktopFileName("VendorSchema.xsd")); vendorData.ReadXml(desktopFileName("Vendors3.xml"), XmlReadMode.IgnoreSchema); 阅读全文
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When theXmlWriteMode.WriteSchema is used as parameter, the resulting XML file is substantiallylarger. When few files are being generated for this data, this approach is acceptable,but if many files are being created, it would be better to create a separate XSD file that can beloaded before the data. 阅读全文
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DataSet cars = new DataSet();cars.WriteXml(desktopFileName("CarWithSchema.xml"), XmlWriteMode.WriteSchema); 阅读全文
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TheImportRow method is useful when theCurrentand Original data row version must be maintained. For example, after editing a datatable, you might want to copy the changedDataRow objects to a different data table butmaintain theOriginal and Current data row version. The ImportRow method on the DataTab 阅读全文