Question

我尝试使用SqlBulkCopy作为一次执行多个INSERT的方法，但由于某些原因，我在运行WriteToServer(DataTable)时遇到了唯一的约束违规。关于这个SqlException的奇怪之处在于它是这样说的。

我的表架构：

CREATE TABLE Product (
  ID   INT IDENTITY (1, 1) PRIMARY KEY,
  Name NVARCHAR(450) UNIQUE NOT NULL, -- Unique constraint being called
  BulkInsertID NCHAR(6) -- Column the constraint is being called on
);

我能想到为什么会发生这种情况的唯一原因是因为我在DataColumn内分配列名时混淆了列名，但我多次检查它们，我找不到它们的任何问题。

Minimal, Complete and Verifiable Example:

class Program
{
    private static SqlConnection connection;
    private static string connectionURL = "Server=ASUS-X750JA\\DIRECTORY;Database=directory;Integrated Security=True;";
    private static Random _random = new Random();

    public static SqlConnection openConnection()
    {
        connection = new SqlConnection(connectionURL);
        connection.Open();
        Console.WriteLine("Opened connection to DB");
        return connection;
    }

    public static void closeConnection()
    {
        connection.Close();
        Console.WriteLine("Closed connection to DB");
    }

    static void Main(string[] args)
    {
        List<string> productNames = new List<string>();
        productNames.Add("Diamond");
        productNames.Add("Gold");
        productNames.Add("Silver");
        productNames.Add("Platinum");
        productNames.Add("Pearl");
        addProducts(productNames);
    }

    private static void addProducts(List<string> productNames)
    {
        const string tableName = "Product";
        DataTable table = new DataTable(tableName);

        string bulkInsertID;
        do
        {
            bulkInsertID = generateID();
        } while (isDuplicateBulkInsertID(tableName, bulkInsertID));

        DataColumn nameColumn = new DataColumn("Name");
        nameColumn.Unique = true;
        nameColumn.AllowDBNull = false;

        DataColumn bulkInsertIDColumn = new DataColumn("BulkInsertID");
        bulkInsertIDColumn.Unique = false;
        bulkInsertIDColumn.AllowDBNull = true;

        table.Columns.Add(nameColumn);
        table.Columns.Add(bulkInsertIDColumn);

        foreach (string productName in productNames)
        {
            DataRow row = table.NewRow();
            row[nameColumn] = productName;
            row[bulkInsertIDColumn] = bulkInsertID;
            table.Rows.Add(row);
        }

        using (SqlConnection connection = openConnection())
        {
            using (SqlBulkCopy bulkCopy = new SqlBulkCopy(connection))
            {
                bulkCopy.DestinationTableName = table.TableName;
                bulkCopy.WriteToServer(table);
            }
        }
    }

    /// <summary>
    /// Generates random 6-character string but it's not like GUID so may need to check for duplicates
    /// </summary>
    /// <returns></returns>
    public static string generateID()
    {
        char[] _base62chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".ToCharArray();
        int length = 6;

        var sb = new StringBuilder(length);

        for (int i = 0; i < length; i++)
            sb.Append(_base62chars[_random.Next(62)]);

        return sb.ToString();
    }

    public static bool isDuplicateBulkInsertID(string tableName, string bulkInsertID)
    {
        string query = string.Format("SELECT BulkInsertID FROM {0} WHERE BulkInsertID = @bulkinsertid", tableName);
        SqlCommand command = new SqlCommand(query, openConnection());
        SqlParameter bulkInsertIDParam = new SqlParameter("@bulkinsertid", SqlDbType.NChar, bulkInsertID.Length);
        bulkInsertIDParam.Value = bulkInsertID;

        command.Parameters.Add(bulkInsertIDParam);
        command.Prepare();
        Task<SqlDataReader> asyncTask = command.ExecuteReaderAsync();
        SqlDataReader reader = asyncTask.Result;
        bool isDuplicate = reader.HasRows;

        closeConnection();
        return isDuplicate;
    }
}

屏幕截图中显示的唯一约束属于Name列，但重复的键值正在发送到BulkInsertID列，我不知道为什么会抛出错误。

编辑：我刚刚更改了架构，使用uniqueidentifier作为bulkInsertID列，并将row[bulkInsertIDColumn] = bulkInsertID更改为row[bulkInsertIDColumn] = Guid.NewGuid().ToString()。当我重新编写代码时，我发现生成的GUID已经运行但是当我查看表时，GUID位于名称列中。所以我可以得出结论，这不是服务器问题，而是程序中的一个问题。

Answer 1

因为您有一个标识列，所以批量插入会尝试将nameColumn插入ID（并忽略它，因为该列是标识列）并且bulkInsertIDColumn插入{{1} }}。只需在插入中添加以下内容即可告诉它转到正确的列。

Name

另一个选项是向using (SqlBulkCopy bulkCopy = new SqlBulkCopy(connection)) { bulkCopy.ColumnMappings.Add("Name", "Name"); //NEW bulkCopy.ColumnMappings.Add("BulkInsertID", "BulkInsertID"); //NEW bulkCopy.DestinationTableName = table.TableName; bulkCopy.WriteToServer(table); }添加ID列，并且不要在其中添加任何值。

table

Answer 2

看起来它会对列UNIQUE抛出BulkInsertID约束违规但是从发布的表架构中看不到它标有该约束，并且在您的代码中我看到您有bulkInsertIDColumn.Unique = false;。您确定没有将其设置为true其他地方。

顺便说一句，对我来说，看起来它正在抛出异常，因为你试图在循环中创建Random()的新实例，如下面的尖代码块所示

    do
    {
        bulkInsertID = generateID(); //calling method generateID
    } while (isDuplicateBulkInsertID(tableName, bulkInsertID));

在generateID()中创建Random class

的新实例

public static string generateID()
{
   ........
    Random _random = new Random(); // creating new instance every time

使用SqlBulkCopy

2 个答案: