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我目前正在处理的项目中遇到外键问题。我首先使用实体​​代码来创建我的数据库。这是我到目前为止所拥有的。

表

单位：身份证，...

类别：身份证，...

CategoryUnits：Id、CategoryId、UnitId

代码优先

类别.cs

public partial class Category : BaseEntity, ILocalizedEntity
{
    private ICollection<CategoryUnits> _categoryUnits;

    ...

    public virtual ICollection<CategoryUnits> CategoryUnits
    {
        get { return _categoryUnits ?? (_categoryUnits = new List<CategoryUnits>()); }
        protected set { _categoryUnits = value; }
    }
}

单位.cs

public class Units : BaseEntity
{
    ...
}

类别单位.cs

public partial class CategoryUnits : BaseEntity, ILocalizedEntity
{
    public virtual int UnitId { get; set; }
    public virtual int CategoryId { get; set; }

    public virtual Units Unit { get; set; }
    public virtual Category Category { get; set; }
}

CategoryUnitsMap.cs

public partial class CategoryUnitsMap : EntityTypeConfiguration<CategoryUnits>
{
    public CategoryUnitsMap()
    {
        this.ToTable("CategoryUnits");
        this.HasKey(cu => cu.Id);

        this.HasRequired(cu => cu.Unit)
            .WithMany()
            .HasForeignKey(cu => cu.UnitId);

        this.HasRequired(cu => cu.Category)
            .WithMany(c => c.CategoryUnits)
            .HasForeignKey(cu => cu.CategoryId);
    }
}

目前发生的情况是，当我在数据迁移程序期间尝试插入数据时收到以下消息：

INSERT 语句与 FOREIGN KEY 约束“CategoryUnits_Category”冲突。冲突发生在数据库“NopDB3”、表“dbo.Category”、“Id”列中。

这是我实际将数据放入表中的代码。

程序.cs

private static void AddDefaultOfficeSuppliesUnitRights()
    {
        try
        {
            var unitIds = new List<int>();
            var sqlSelectStatement = "Select * From Units With(NoLock)";
            var units = new DataSet();

            using (var sqlCommand = new SqlCommand(sqlSelectStatement, sqlCon))
            {
                var sqlAdapter = new SqlDataAdapter();
                sqlAdapter.SelectCommand = sqlCommand;
                sqlCon.Open();
                sqlAdapter.Fill(units);
                sqlCon.Close();
            }

            foreach (DataRow dr in units.Tables[0].Rows)
            {
                var unitId = Int32.Parse(dr["Id"].ToString());
                unitIds.Add(unitId);
            }

            var sqlInsertStatement = GenerateCategoryUnitsForOfficeSupplies("Insert Into CategoryUnits (UnitId, CategoryId) Values (cuUnitId, 19)", unitIds);
            using (var sqlCommand = new SqlCommand(sqlInsertStatement, sqlCon))
            {
                sqlCon.Open();
                sqlCommand.ExecuteNonQuery();
                sqlCon.Close();
            }

            Console.WriteLine("Default Office Supply CategoryUnits Added");
        }
        //Something went wrong
        catch (Exception ex)
        {
            Console.WriteLine("Error in Add Default Category Units for Office Supplies: " + ex.Message);
        }
        //Close out sql connection
        finally
        {
            if (sqlCon.State != ConnectionState.Closed) sqlCon.Close();
        }
    }

private static string GenerateCategoryUnitsForOfficeSupplies(string sqlInsertStatement, List<int> unitIds)
    {
        var sqlInsertStatements = string.Empty;
        foreach (var unitId in unitIds)
        {
            sqlInsertStatements += sqlInsertStatement.Replace("cuUnitId", unitId.ToString()) + "; ";
        }

        return sqlInsertStatements;
    }

最奇怪的是，当我通过 sql 语句手动插入数据时，它工作正常并且没有错误。任何的意见都将会有帮助。

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