postgresql - 在 .net core 3.0 中使用 postgresql 作为数据库时代码优先错误中的数据迁移

Question

我正在使用代码优先方法迁移数据，数据库是 postgresql，添加迁移工作正常，但更新数据库给出错误“42601:语法错误在或接近“已生成”，下面有更多详细信息:

> PM> add-migration migration
>     Build started...
>     Build succeeded.
>     To undo this action, use Remove-Migration.
>     PM> update-database
>     Build started...
>     Build succeeded.
>     [15:18:48 Error] Microsoft.EntityFrameworkCore.Database.Command
>     Failed executing DbCommand (298ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
>     CREATE TABLE "Customers" (
>         "CustomerId" integer NOT NULL GENERATED BY DEFAULT AS IDENTITY,
>         "CustomerName" text NULL,
>         CONSTRAINT "PK_Customers" PRIMARY KEY ("CustomerId")
>     );
>     
>     Npgsql.PostgresException (0x80004005): 42601: syntax error at or near "GENERATED"
>        at Npgsql.NpgsqlConnector.<>c__DisplayClass160_0.<<DoReadMessage>g__ReadMessageLong|0>d.MoveNext()
>     --- End of stack trace from previous location where exception was thrown ---
>        at Npgsql.NpgsqlConnector.<>c__DisplayClass160_0.<<DoReadMessage>g__ReadMessageLong|0>d.MoveNext()
>     --- End of stack trace from previous location where exception was thrown ---
>        at Npgsql.NpgsqlDataReader.NextResult(Boolean async, Boolean isConsuming)
>        at Npgsql.NpgsqlDataReader.NextResult()
>        at Npgsql.NpgsqlCommand.ExecuteReaderAsync(CommandBehavior behavior, Boolean async, CancellationToken cancellationToken)
>        at Npgsql.NpgsqlCommand.ExecuteNonQuery(Boolean async, CancellationToken cancellationToken)
>        at Npgsql.NpgsqlCommand.ExecuteNonQuery()
>        at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteNonQuery(RelationalCommandParameterObject
> parameterObject)
>        at Microsoft.EntityFrameworkCore.Migrations.MigrationCommand.ExecuteNonQuery(IRelationalConnection
> connection, IReadOnlyDictionary`2 parameterValues)
>        at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.ExecuteNonQuery(IEnumerable`1
> migrationCommands, IRelationalConnection connection)
>        at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String
> targetMigration)
>        at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String
> targetMigration, String contextType)
>        at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabaseImpl(String
> targetMigration, String contextType)
>        at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase.<>c__DisplayClass0_0.<.ctor>b__0()
>        at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action
> action)
>       Exception data:
>         Severity: ERROR
>         SqlState: 42601
>         MessageText: syntax error at or near "GENERATED"
>         Position: 63
>         File: src\backend\parser\scan.l
>         Line: 1067
>         Routine: scanner_yyerror
>     42601: syntax error at or near "GENERATED"

(由于这是代码优先方法，所以下面是模型) 型号:

     public class Customer1
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int CustomerId { get; set; }
        public string CustomerName { get; set; }
    }


**Update: Got a solution:
in migrationbuilder(created after add-migration command),i simply changed** 
NpgsqlValueGenerationStrategy.IdentityByDefaultColumn 
to 
NpgsqlValueGenerationStrategy.serialcolumn
**and saved it ,and then run the command update-database ,and it worked**

Answer 1

您似乎正在激活 IDENTITY columns 功能，该功能仅在 PostgreSQL 10 中引入。(当您是 9.4.20 时)

我建议您可以升级到更新版本的 PostgreSQL。

引用https://dba.stackexchange.com/questions/198777/how-to-add-a-postgresql-10-identity-column-to-an-existing-table