Question

我想使用Entity Framework 4+删除所有表（所有实体）的内容。怎么办呢？

Answer 1

假设底层数据库是MSSQL，这将比涉及删除单个实体对象的任何内容执行更多，更多。

foreach (var tableName in listOfTableNames)
{
    context.ExecuteStoreCommand("TRUNCATE TABLE [" + tableName + "]");
}

当然，如果您的表具有外键关系，则需要按正确的顺序设置表名列表，以便在清除任何可能的主键表之前清除外键表。依靠。

Answer 2

对于懒惰的代码，我在寻找答案时自己出现了代码：

public static void ClearDatabase<T>() where T : DbContext, new()
    {
        using (var context = new T())
        {
            var tableNames = context.Database.SqlQuery<string>("SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = 'BASE TABLE' AND TABLE_NAME NOT LIKE '%Migration%'").ToList();
            foreach (var tableName in tableNames)
            {
                context.Database.ExecuteSqlCommand(string.Format("DELETE FROM {0}", tableName));
            }

            context.SaveChanges();
        }
    }

简短说明：我没有因为缺少权限而截断表，如果这对你来说不是问题，请随意这样做。 where语句忽略表__MigrationHistory。

更新：经过一些研究后，我想出了更好的解决方案（不是很好但只删除了必需的列）：

public static void ClearDatabase(DbContext context)
    {
        var objectContext = ((IObjectContextAdapter)context).ObjectContext;
        var entities = objectContext.MetadataWorkspace.GetEntityContainer(objectContext.DefaultContainerName, DataSpace.CSpace).BaseEntitySets;
        var method = objectContext.GetType().GetMethods().First(x => x.Name == "CreateObjectSet");
        var objectSets = entities.Select(x => method.MakeGenericMethod(Type.GetType(x.ElementType.FullName))).Select(x => x.Invoke(objectContext, null));
        var tableNames = objectSets.Select(objectSet => (objectSet.GetType().GetProperty("EntitySet").GetValue(objectSet, null) as EntitySet).Name).ToList();

        foreach (var tableName in tableNames)
        {
            context.Database.ExecuteSqlCommand(string.Format("DELETE FROM {0}", tableName));
        }

        context.SaveChanges();
    }

Answer 3

对于EF 6：

DbSet<Entity>.RemoveRange(DbSet<Entity>);

Answer 4

使用类似的代码遍历表格：

context.GetType().GetProperties()
.Where(propertyInfo => propertyInfo.PropertyType == typeof(Table<>))
.Select(propertyInfo => propertyInfo.GetValue(context, null) as ITable).ToList()
.Foreach(table =>
{
    //code that deletes the actual tables records.
}
);

Answer 5

我想尝试改善@Wojciech Markowski的优秀答案。

如果你像我一样懒，不想检查外键限制，你可以使用这种方法：

        private void ClearDatabase(TContext context)
    {
            // disable all foreign keys
            //context.Database.ExecuteSqlCommand("EXEC sp_MSforeachtable @command1 = 'ALTER TABLE ? NOCHECK CONSTRAINT all'");

            List<string> tableNames = context.Database.SqlQuery<string>("SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = 'BASE TABLE' AND TABLE_NAME NOT LIKE '%Migration%'").ToList();

            for (int i = 0; tableNames.Count>0; i++)
            {
                try
                {
                    context.Database.ExecuteSqlCommand(string.Format("DELETE FROM {0}", tableNames.ElementAt(i % tableNames.Count)));
                    tableNames.RemoveAt(i % tableNames.Count);
                    i = 0;
                }
                catch { } // ignore errors as these are expected due to linked foreign key data             
            }


            context.SaveChanges();
    }

ClearDatabase方法遍历表列表并清除它们。如果找到FK约束，则捕获异常并继续下一个表。最后，所有表格都将被删除。

此外，如果您不介意放弃所有FK约束，您可以通过以下行禁用所有这些约束：

context.Database.ExecuteSqlCommand("EXEC sp_MSforeachtable @command1 = 'ALTER TABLE ? NOCHECK CONSTRAINT all'");

还有一件事：如果要删除所有表而不是清除它们，请替换以下行：

context.Database.ExecuteSqlCommand(string.Format("DELETE FROM {0}", tableNames.ElementAt(i % tableNames.Count)));

使用：

context.Database.ExecuteSqlCommand(string.Format("DROP TABLE {0}", tableNames.ElementAt(i % tableNames.Count)));

我亲自在实体框架6上使用代码优先迁移检查了这个答案。

编辑：更好的版本：

        private void ClearDatabase(MrSaleDbContext context)
    {
        //Optional: disable all foreign keys (db-schema will be loosed).
        //context.Database.ExecuteSqlCommand("EXEC sp_MSforeachtable @command1 = 'ALTER TABLE ? NOCHECK CONSTRAINT all'");

        List<string> tableNames = context.Database.SqlQuery<string>("SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = 'BASE TABLE' AND TABLE_NAME NOT LIKE '%Migration%' AND TABLE_NAME NOT LIKE 'AspNet%'").ToList();

        for (int i = 0; tableNames.Count > 0; i++)
        {
            try
            {
                //To delete all tables and not just clean them from data, replace "DELETE FROM {0}" in "DROP TABLE {0}":
                context.Database.ExecuteSqlCommand(string.Format("DELETE FROM {0}", tableNames.ElementAt(i % tableNames.Count)));
                tableNames.RemoveAt(i % tableNames.Count);
                i = -1; //flag: a table was removed. in the next iteration i++ will be the 0 index.
            }
            catch (System.Data.SqlClient.SqlException e)   // ignore errors as these are expected due to linked foreign key data    
            {                    
                if ((i % tableNames.Count) == (tableNames.Count - 1))
                {
                    //end of tables-list without any success to delete any table, then exit with exception:
                    throw new System.Data.DataException("Unable to clear all relevant tables in database (foriegn key constraint ?). See inner-exception for more details.", e);
                }

            }

        }

catch块中的if语句检查我是否到达了表列表的最后一个索引而没有删除任何表。在这种情况下，不是进入无限循环，而是抛出异常并退出for。

Answer 6

truncate无法在外键中删除。

然后我为DbContext做了扩展方法。

用法很简单。

db.Truncates（）; //所有表删除。

db.Truncates（＆＃34; Test1＆＃34;，＆＃34; Test2＆＃34;）; //仅＆＃34; Test1，Test2＆＃34;表删除

public static class DbContextExtension
{
    public static int Truncates(this DbContext db, params string[] tables)
    {
        List<string> target = new List<string>();
        int result = 0;

        if (tables == null || tables.Length == 0)
        {
            target = db.GetTableList();
        }
        else
        {
            target.AddRange(tables);
        }

        using (TransactionScope scope = new TransactionScope())
        {
            foreach (var table in target)
            {
                result += db.Database.ExecuteSqlCommand(string.Format("DELETE FROM  [{0}]", table));
                db.Database.ExecuteSqlCommand(string.Format("DBCC CHECKIDENT ([{0}], RESEED, 0)", table));
            }

            scope.Complete();
        }

        return result;
    }

    public static List<string> GetTableList(this DbContext db)
    {
        var type = db.GetType();

        return db.GetType().GetProperties()
            .Where(x => x.PropertyType.Name == "DbSet`1")
            .Select(x => x.Name).ToList();
    }
}

Answer 7

（在.NetCore中）您可以在表上使用RemoveRange，并将表本身作为参数。

Tablename.RemoveRange(Tablename);

Answer 8

这对我有用... EF v3.1.5

stdin_open: true
tty: true

删除实体框架中的所有实体

8 个答案: