インデックスを作成しクエリを高速化したい場合は、[Index]属性を追加し、以下のように自動的にコードを生成します。
update-database databaseを行った場合、エラーは以下の通りです:
System.Data.SqlClient.SqlException (0x80131904): table 'dbo. 「アカウント」の「電話」列はインデックスのキーカラムとして使用できません。
at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action'1 wrapCloseInAction)
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action'1 wrapCloseInAction)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
In System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout, Boolean asyncWrite)
In System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource'1 complete, String methodName, Boolean sendToPipe, Int32 timeout, Boolean& usedCache, Boolean asyncWrite、ブール値を inRetry)
In System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
System.Data.Entity.Infrastructure.Interception.DbCommandDispatcherにて。 <NonQuery>b__0(DbCommand t, DbCommandInterceptionContext'1 c)
System.Data.Entity.Infrastructure.Interception.InternalDispatcher'1.Dispatch[TTarget,TInterceptionContext,TResult](TTarget target, Func'3 operation, Ti nterceptionContext interceptionContext、Action'3実行中、Action'3実行完了)
System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.NonQuery(DbCommandコマンド、DbCommandInterceptionContext interceptionContext)
In System.Data.Entity.Internal.InterceptableDbCommand.ExecuteNonQuery()
In System.Data.Entity.Migrations.DbMigrator.ExecuteSql(MigrationStatement migrationStatement, DbConnection connection, DbTransaction transaction, DbInterceptionContext インターセプトコンテキスト)
System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.ExecuteSql(MigrationStatement migrationStatement, DbConnection connection, DbTransaction transaction transaction、DbInterceptionContext interceptionContext)
System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsInternal(IEnumerable'1 migrationStatements, DbConnection connection, DbTransaction transaction, DbInterceptionContext interceptionContext)
In System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsWithinTransaction(IEnumerable'1 migrationStatements, DbTransaction transaction, DbInterceptionContext インターセプトコンテキスト)
In System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsWithinNewTransaction(IEnumerable'1 migrationStatements, DbConnection connection, DbInterceptionContext インターセプトコンテキスト)
System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsInternal(IEnumerable'1 migrationStatements, DbConnection connection, DbInterceptionContext interceptionContext)
at System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsInternal(IEnumerable'1 migrationStatements, DbConnection connection)
System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClass32. <ExecuteStatements>b__30()
In System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.<>c__DisplayClass1. <Execute>b__0()
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func'1 operation)
System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action operation)
System.Data.Entity.Migrations.DbMigrator.ExecuteStatements(IEnumerable'1 migrationStatements, DbTransaction existingTransaction)
System.Data.Entity.Migrations.DbMigrator.ExecuteStatements(IEnumerable'1 migrationStatements)
at System.Data.Entity.Migrations.Infrastructure.MigratorBase.ExecuteStatements(IEnumerable'1 migrationStatements)
In System.Data.Entity.Migrations.DbMigrator.ExecuteOperations(String migrationId, VersionedModel targetModel, IEnumerable'1 operations, IEnumerable'1 systemOperations, Boolean ダウングレード、ブール自動)
at System.Data.Entity.Migrations.DbMigrator.ApplyMigration(DbMigration migration, DbMigration lastMigration)
System .Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.ApplyMigration(DbMigration migration, DbMigration lastMigration)
at System.Data.Entity.Migrations.DbMigrator.Upgrade(IEnumerable'1 pendingMigrations, String targetMigrationId, String lastMigrationId)
at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.Upgrade(IEnumerable'1 pendingMigrations, String targetMigrationId, string lastMigrationId)
at System.Data.Entity.Migrations.DbMigrator.UpdateInternal(String targetMigration)
In System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClasse. <Update>b__d()
at System.Data.Entity.Migrations.DbMigrator.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
at System.Data.Entity.Migrations.Infrastructure.MigratorBase.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
at System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration)
In System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update(String targetMigration)
at System.Data.Entity.Migrations.Design.ToolingFacade.UpdateRunner.RunCore()
In System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.Run()
ClientConnectionId:2b5f614b-caab-4be6-bc1b-a813b7356739
エラー番号:1919、州:1、クラス:16
テーブル、ドボ。 「アカウント」の「電話」列はインデックスのキーカラムとして使用できません。
このエラーの理由は、efのすべての文字列特性がデフォルトでNVARCHAR(Max)型であるためです。
解は以下の通りです:
文字列の長さを実行します
写真に示す通り、創作は成功しています!
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掲載地 2017/11/23 18:47:15
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