如果只是修改了字段,执行这些命令会提示 Table 'XXXXXXXXXXXXXXXXXXX' already exists 表示这个迁移会执行建表操作,已存在导致迁移失败。 楼主解决方法如下: 输入get-help entityframeworkcore 获取指令帮助。 使用Script-Migration Generates a SQL script from migrations.(脚本迁移从迁移生成SQL脚本。) 执行 执行完毕会...
Check if a table column value exists in another table column using linq Check to see if last record Checking Null in where condition using entity framework Code first approach with database table already exists. Code First Entity : The property is part of the object's key information and can...
注意使用 EnsureCreated 函数创建之后,将在下次调用 Database.Migrate 函数时提示下面代码 Microsoft.Data.Sqlite.SqliteException:“SQLite Error 1: 'table "ResourceModel" already exists'.” 1. 如果软件更新了,需要修改 ResourceModel 的内容,添加一个属性 public class ResourceModel { [DatabaseGenerated(DatabaseG...
该属性称为“已删除”,并应具有默认值"false“。数据库中的所有以前的条目都需要分配这个默认值。我使用的是自动迁移,因此不可能在迁移中更改向上和删除函数(至少据我所知)。 我尝试在group类中创建新属性,但是当psql中运行SQL代码(ALTER TABLE "dbo"."Group" ADD "Deleted" boolean NOT NU...
Would like to have a check for table exists before an exception is thrown when a table already exists for a call to RelationalDatabaseCreator.CreateTables() When attempting to execute the following code, with the intention of creating da...
It becomes tricky to know whether an optional dependent entity exists or not when it shares a table with its principal entity. This is because there is a row in the table for the dependent because the principal needs it, regardless of whether or not the dependent exists. The way to handle...
There is another way around the nullability problem, which is to simply map the value object type to its own table, thus physically splitting the value object data from the rest of the object to which it belongs. While this may be a good solution for some scenarios, ...
MagazineId = table.Column<int>(nullable: false) .Annotation("Sqlite:Autoincrement", true) Let’s continue to see how this works out. Using the migrations script command, “dotnet ef migrations script,” to show what will be sent to the database, I can see that the primary key value ...
DESCRIBE TABLE产生Error 1146。 创建`table`产生Error 1051: Table already exists。 SELECT * FROM information_schema.TABLES WHERE TABLE_NAME ='table'产生一个空结果集。 运行FLUSH TABLES命令,该命令已成功执行,但结果为0 row(s) affected。 REPAIR TABLE产生一个Operation failed消息,指出Table doesn't exist...
10 UniqueTableNameTempDb: true, 30 CustomSqlPostProcess: null, 11 CustomDestinationTableName: null, 31 IncludeGraph: false, 12 CustomSourceTableName: null, 32 OmitClauseExistsExcept: false, 13 CustomSourceDestinationMappingColumns: null, 33 DoNotUpdateIfTimeStampChanged: false, 14 OnConflictUpdateWh...