Entity framework 和 sql 身份问题

Question

我需要重置我的 table ID（身份），因为每次更新时，我的 ID 都必须从 1 开始，因为他们每次都会将其增加到超过 60 000 条记录.我该怎么做？

using (DailyContext context= DailyContext.Create())
{
    //cleaning old prices
    foreach (var price in context.Prices)
    {
        context.DeleteObject(price);
    }
    context.SaveChanges();


    for (int i = 0; i < newElements.Total; i++)
    {
        var newPrice = new Price()
        {

            Date = newElements.From.AddDays(i),
            PriceFrom = newElements.Price,
            TotalNights = newElements.TotalNights,
            Profit = newElements.Profit
        };
        context.AddToPrices(newPrice);
    }

    context.SaveChanges();
}

Answer 1

要重置身份，您需要在 EF 之外进行，并且必须进行原始查询。您需要运行的查询是带有 RESEED 参数的 DBCC CHECKIDENT。

using (DailyContext context= DailyContext.Create())
{
    //cleaning old prices
    foreach (var price in context.Prices)
    {
        context.DeleteObject(price);
    }
    context.SaveChanges();

    //Reseed the identity to 0.
    context.Database.ExecuteSqlCommand("DBCC CHECKIDENT (Prices, RESEED, 0)");
    //Roll the identity forward till it finds the last used number.
    context.Database.ExecuteSqlCommand("DBCC CHECKIDENT (Prices, RESEED)");

    for (int i = 0; i < newElements.Total; i++)
    {
        var newPrice = new Price()
        {

            Date = newElements.From.AddDays(i),
            PriceFrom = newElements.Price,
            TotalNights = newElements.TotalNights,
            Profit = newElements.Profit
        };
        context.AddToPrices(newPrice);
    }

    context.SaveChanges();
}

编辑：

这是一个仅使用 SqlCommand 执行的版本，不依赖于 Entity Framework。

using (var connection = new SqlConnection(_connectionString))
{
    connection.Open();
    using (SqlTransaction trans = connection.BeginTransaction("PricesCleanup"))
    using (var command = new SqlCommand("", connection, trans))
    {
        //Reseed the identity to 0.
        command.CommandText = "DBCC CHECKIDENT (Prices, RESEED, 0)";
        command.ExecuteNonQuery();

        //Roll the identity forward till it finds the last used number.
        command.CommandText = "DBCC CHECKIDENT (Prices, RESEED)";
        command.ExecuteNonQuery();
        trans.Commit();
    }
}

Answer 2

不要在 EF 中单独循环和删除价格，只需使用 ExecuteSqlCommand 到 TRUNCATE table。

这既清空了它（比 DELETE 更有效）又重置了 IDENTITY 列值。

Entity framework 和 sql 身份问题

Entity framework and sql identity issue

c#

sql-server

asp.net

entity-framework

uniqueidentifier