如何找到违反约束条件的列？

Question

我有一个强类型数据集，在处理空值时出现以下错误：

System.Data.ConstraintException: 无法启用约束条件。一个或多个行包含违反非空、惟一或外键约束条件的值。 at System.Data.DataTable.EnableConstraints() at System.Data.DataTable.EndLoadData() at System.Data.Common.DataAdapter.FillFromReader(DataSet dataset, DataTable datatable, String srcTable, DataReaderContainer dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) at System.Data.Common.DataAdapter.Fill(DataTable[] dataTables, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) at System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataTable[] dataTables, Int32 startRecord, Int32 maxRecords, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataTable dataTable) at Fruits.DataAccess.FruitsTableAdapters.FruitsExtTableAdapter.GetFruits(String User, String Filter) at Fruits.DataAccess.FruitsDataAccess.GetFruits(String User, String Filter) at Fruits.WebServices.External.Fruity.GetFruits(String Filter)

所有列都填充了我正在测试它的单行记录。

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

- Mathematics

---

简短回答：不行 你可以使用动态SQL做一些不好的事情，但我不建议这样做。 - Tristan

谢谢@Tristan，我现在修改了我的问题。 - Mathematics

尝试使用 SELECT f.* FROM dbo.Fruits AS f WHERE NOT EXISTS (SELECT 1 FROM dbo.Categories AS c WHERE c.id = f.categoryID); 查找违反外键约束的行。 - ypercubeᵀᴹ

Answer 1

DataSet / DataTable有属性可获取关于错误的更多详细信息，因此这些详细信息并非像您可能认为的那样在异常本身中，这就是诀窍。请参见http://www.codeproject.com/Tips/405938/Debugging-DataSet-Constraint-Errors

示例：

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));
        }
    }
}

- AFract

---

在传统项目中的救星。谢谢！ - Kamil Stadryniak

如果在Visual Studio上调试并停在异常处，您可以在即时窗口中键入：yourDataset.yourTable.GetErrors()[0].RowError，然后您将看到第一个约束错误。 - Ken Richards

Answer 2

您可以在您的代码中使用这种方法。.NET检查数据集从而抛出异常。

       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);
                }
            }
        }                                                    
}

- Javier Gaviria

---

我没有测试过这个，但我会因为你的努力而接受它，谢谢。 - Mathematics

Answer 3

如果有人（就像我现在这样）正在使用VB.NET中的DataSet处理遗留项目，为了节省大家一分钟的时间，我发布了@AFract答案的VB.NET版本。希望它适用于这里：

        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

- Kamil Stadryniak

Answer 4

问题出在数据集中的一列名称不匹配，不确定是什么触发了它，但将列名与一个返回的固定列名匹配解决了问题。

我还使用了强类型数据集的“预览数据”功能，这帮助我找到了问题。

- Mathematics