I have a strongly typed data set which throws this error for null values,
System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. 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)
All of the columns are populated with 1 single row I am testing it with,
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
SELECT f.* FROM dbo.Fruits AS f WHERE NOT EXISTS (SELECT 1 FROM dbo.Categories AS c WHERE c.id = f.categoryID);
to find which rows violate the FK constraint. – ypercubeᵀᴹ