C# 如何找到违反约束的列？

我有一个强类型数据集，它为空值抛出这个错误

System.Data.ConstraintException:未能启用约束。一个或多个 更多行包含违反非空、唯一或外键的值 限制。在System.Data.DataTable.EnableConstraints处 System.Data.DataTable.EndLoadData位于 System.Data.Common.DataAdapter.FillFromReaderDataSet数据集， DataTable DataTable、字符串srcTable、dataReader容器dataReader、， Int32 startRecord、Int32 maxRecords、DataColumn parentChapterColumn、， 对象parentChapterValue位于 System.Data.Common.DataAdapter.FillDataTable[]数据表， IDataReader数据读取器，Int32 startRecord，Int32 maxRecords位于 System.Data.Common.DbDataAdapter.FillInternalDataSet数据集， DataTable[]datatables，Int32 startRecord，Int32 maxRecords，字符串 srcTable，IDbCommand命令，CommandBehavior行为 System.Data.Common.DbDataAdapter.FillDataTable[]数据表，Int32 startRecord、Int32 maxRecords、IDbCommand、CommandBehavior System.Data.Common.DbDataAdapter.FillDataTable上的行为 数据表位于 Fruits.DataAccess.FruitsStableApters.FruitsettableAdapter.GetFruitsString 用户，字符串筛选器位于 Fruits.DataAccess.FruitsDataAccess.GetFruitsString用户，字符串 在Fruits.WebServices.External.Fruity.getfruitssString处过滤 滤器

所有列都填充了一行，我正在测试它

USE [FruitDataBase]
GO

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[Fruits](
    [ID] [int] NOT NULL,
    [CategoryID] [int] NOT NULL,
    [Title] [nvarchar](255) NOT NULL,
    [URL] [nvarchar](255) NOT NULL,
    [Status] [nvarchar](70) NOT NULL,
    [Description] [nvarchar](1024) NULL,
    [User1] [nvarchar](50) NOT NULL,
    [Date] [datetime] NOT NULL,
    [User2] [nvarchar](50) NULL,
    [Date2] [datetime] NULL,
    [Impact] [nvarchar](255) NULL,
    [Solution] [nvarchar](1024) NULL,
 CONSTRAINT [PK_Fruits] PRIMARY KEY CLUSTERED 
(
    [ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

ALTER TABLE [dbo].[Fruits]  WITH CHECK ADD  CONSTRAINT [FK_Fruits_Categories] FOREIGN KEY([CategoryID])
REFERENCES [dbo].[Categories] ([ID])
GO

ALTER TABLE [dbo].[Fruits] CHECK CONSTRAINT [FK_Fruits_Categories]
GO

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问题是其中一个列名在数据集中不匹配，不确定是什么触发了它，但将列名与返回的列名匹配修复了该问题

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我还使用了强类型数据集的预览数据功能，这帮助我解决了问题。

数据集/数据表具有属性，可以获取有关错误的更多详细信息

因此，这些细节本身并不像你所想的那样是例外，这就是诀窍。看

样本：

catch (ConstraintException)
{
    DataRow[] rowErrors = this.YourDataSet.YourDataTable.GetErrors();

    System.Diagnostics.Debug.WriteLine("YourDataTable Errors:" 
        + rowErrors.Length);

    for (int i = 0; i < rowErrors.Length; i++)
    {
        System.Diagnostics.Debug.WriteLine(rowErrors[i].RowError);

        foreach (DataColumn col in rowErrors[i].GetColumnsInError())
        {
            System.Diagnostics.Debug.WriteLine(col.ColumnName 
                + ":" + rowErrors[i].GetColumnError(col));
        }
    }
}

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您可以在代码中使用此方法。NET检查数据集，从而引发异常

       public void CheckDataSet(DataSet dataSet)
       {                                                              
        Assembly assembly = Assembly.LoadFrom(@"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\System.Data.dll");
        Type type = assembly.GetType("System.Data.ConstraintEnumerator");
        ConstructorInfo ctor = type.GetConstructor(new[] { typeof(DataSet) });
        object instance = ctor.Invoke(new object[] { dataSet });                
        BindingFlags bf = BindingFlags.Instance | BindingFlags.Public;
        MethodInfo m_GetNext = type.GetMethod("GetNext", bf);

        while ((bool)m_GetNext.Invoke(instance, null))
        {
            bool flag = false;
            MethodInfo m_GetConstraint = type.GetMethod("GetConstraint", bf);                    
            Constraint constraint = (Constraint) m_GetConstraint.Invoke(instance, null);
            Type constraintType = constraint.GetType();
            BindingFlags bfInternal = BindingFlags.Instance | BindingFlags.NonPublic;
            MethodInfo m_IsConstraintViolated = constraintType.GetMethod("IsConstraintViolated", bfInternal);                    
            flag = (bool)m_IsConstraintViolated.Invoke(constraint, null);
            if (flag)                    
                Debug.WriteLine("Constraint violated, ConstraintName: " + constraint.ConstraintName + ", tableName: " + constraint.Table);                                            
        }

        foreach (DataTable table in dataSet.Tables)
        {
            foreach (DataColumn column in table.Columns)
            {
                Type columnType = column.GetType();
                BindingFlags bfInternal = BindingFlags.Instance | BindingFlags.NonPublic;

                bool flag = false;
                if (!column.AllowDBNull)
                {                            
                    MethodInfo m_IsNotAllowDBNullViolated = columnType.GetMethod("IsNotAllowDBNullViolated", bfInternal);                                                        
                    flag = (bool)m_IsNotAllowDBNullViolated.Invoke(column, null);
                    if (flag)
                    {
                        Debug.WriteLine("DBnull violated  --> ColumnName: " + column.ColumnName + ", tableName: " + column.Table.TableName);
                    }
                }
                if (column.MaxLength >= 0)
                {
                    MethodInfo m_IsMaxLengthViolated = columnType.GetMethod("IsMaxLengthViolated", bfInternal);                            
                    flag = (bool)m_IsMaxLengthViolated.Invoke(column, null);                            
                    if (flag)                            
                        Debug.WriteLine("MaxLength violated --> ColumnName: " + column.ColumnName + ", tableName: " + column.Table.TableName);
                }
            }
        }                                                    
}

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以防有人像我一样正在VB.NET中使用遗留项目的数据集来节省你们一分钟，我在@AFract答案上发布了一个VB.NET版本。希望它适合这里：

        Catch ex As ConstraintException
            Dim rowErrors = this.YourDataSet.YourDataTable.GetErrors()
            System.Diagnostics.Debug.WriteLine("YourDataTable Errors:" & rowErrors.Length)
            For i = 0 To rowErrors.Length - 1
                For Each col As DataColumn In rowErrors(i).GetColumnsInError()
                    System.Diagnostics.Debug.WriteLine(col.ColumnName & ":" & rowErrors(i).GetColumnError(col))
                Next
            Next
        End Try

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简短回答：不，你可以用动态sql做一些不好的事情，但我不建议这样做。谢谢@Tristan，我现在改变了我的问题尝试从dbo中选择f.*f。水果作为f，如果不存在，从dbo中选择1。类别作为c，其中c.id=f.categoryID；为了找出哪些行违反了FK约束。我没有对此进行测试，但我会接受它，感谢遗留项目中的Life saver。非常感谢。如果使用Visual Studio调试并在异常时停止，则可以在即时窗口中键入：yourDataset.yourTable.GetErrors[0].RowError，您将看到第一个约束错误