我正在尝试通过 MySql 数据库中的迁移来重命名列。
这是我的迁移:
public override void Up()
{
//RenameColumn("Docks", "ProfileId", "SecondId"); <!-- doesn't work either
RenameColumn("Docks", "ProfileId", "SecondId", anonymousArguments: new { ColumnType = "int" });
}
public override void Down()
{
//RenameColumn("Docks", "SecondId", "ProfileId"); <!-- doesn't work either
RenameColumn("Docks", "SecondId", "ProfileId", anonymousArguments: new { ColumnType = "int" });
}
当我运行 Update-Database 时，它向我喷出一个大错误(如果你想查看整个错误，请打开代码片段)，其中包括:
MySql.Data.MySqlClient.MySqlException (0x80004005): Parameter '@columnType' must be defined.
MySql.Data.MySqlClient.MySqlException(0x80004005): Fatal error encountered during command execution.-- - > MySql.Data.MySqlClient.MySqlException(0x80004005): Parameter '@columnType' must be defined. at MySql.Data.MySqlClient.Statement.SerializeParameter(MySqlParameterCollection
parameters, MySqlPacket packet, String parmName, Int32 parameterIndex) at MySql.Data.MySqlClient.Statement.InternalBindParameters(String sql, MySqlParameterCollection parameters, MySqlPacket packet) at MySql.Data.MySqlClient.Statement.BindParameters()
at MySql.Data.MySqlClient.PreparableStatement.Execute() at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior) at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior) at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery()
at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.
< NonQuery> b__0(DbCommand t, DbCommandInterceptionContext `1 c) at System.Data.Entity.Infrastructure.Interception.InternalDispatcher` 1. Dispatch[TTarget, TInterceptionContext, TResult](TTarget target, Func `3 operation, TInterceptionContext interceptionContext,
Action` 3 executing, Action `3 executed) at System.Data.Entity.Infrastructure.Interception.DbCommandDispatcher.NonQuery(DbCommand command, DbCommandInterceptionContext interceptionContext) at System.Data.Entity.Internal.InterceptableDbCommand.ExecuteNonQuery()
at System.Data.Entity.Migrations.DbMigrator.ExecuteSql(MigrationStatement migrationStatement, DbConnection connection, DbTransaction transaction, DbInterceptionContext interceptionContext) at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.ExecuteSql(MigrationStatement
migrationStatement, DbConnection connection, DbTransaction transaction, DbInterceptionContext interceptionContext) at System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsInternal(IEnumerable` 1 migrationStatements, DbConnection connection, DbTransaction
transaction, DbInterceptionContext interceptionContext) at System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsWithinTransaction(IEnumerable `1 migrationStatements, DbTransaction transaction, DbInterceptionContext interceptionContext) at System.Data.Entity.Migrations.DbMigrator.ExecuteStatementsWithinNewTransaction(IEnumerable`
1 migrationStatements, DbConnection connection, DbInterceptionContext interceptionContext) at 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) at System.Data.Entity.Migrations.DbMigrator.
<> c__DisplayClass32.
< ExecuteStatements> b__30() at System.Data.Entity.Infrastructure.DefaultExecutionStrategy.Execute(Action operation) at System.Data.Entity.Migrations.DbMigrator.ExecuteStatements(IEnumerable `1 migrationStatements, DbTransaction existingTransaction) at System.Data.Entity.Migrations.DbMigrator.ExecuteStatements(IEnumerable`
1 migrationStatements) at System.Data.Entity.Migrations.Infrastructure.MigratorBase.ExecuteStatements(IEnumerable `1 migrationStatements) at System.Data.Entity.Migrations.DbMigrator.ExecuteOperations(String migrationId, VersionedModel targetModel,
IEnumerable` 1 operations, IEnumerable `1 systemOperations, Boolean downgrading, Boolean auto) at System.Data.Entity.Migrations.DbMigrator.ApplyMigration(DbMigration migration, DbMigration lastMigration) at 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) at 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) at System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update(String targetMigration) at System.Data.Entity.Migrations.Design.ToolingFacade.UpdateRunner.RunCore() at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.Run()
Fatal error encountered during command execution.详细模式在抛出错误之前生成了以下 sql 查询:
set @columnType := (select case lower(IS_NULLABLE)
when 'no' then CONCAT(column_type, ' not null ')
when 'yes' then column_type end
from information_schema.columns
where table_name = 'Docks'
and column_name = 'ProfileId');
set @sqlstmt := (select concat('alter table `Docks`
change `ProfileId` `SecondId` ' , @columnType));
prepare stmt from @sqlstmt;
execute stmt;
deallocate prepare stmt;
我很好奇，所以我将 sql 复制并粘贴到数据库中，它按预期执行而没有错误，并成功地使用正确的 int(11) 类型重命名了该列。
那么，即使它正在生成(显然)有效的 sql，我该如何防止抛出此错误？
编辑:要注意，即使我没有使用 dotconnect，这里接受的答案对我也有效。
最佳答案
找到上述问题的解决方案:(MySql.Data.MySqlClient.MySqlException):据我所知，它与连接器的升级有关。
您需要在连接字符串中添加 Allow User Variables=True 才能使用自定义变量。
点击此链接供您引用:
关于c# - MySql 数据库中的 EF 重命名列，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49080607/