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使用SqlBulkCopy时，在错误的列上违反了唯一约束

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我试图使用 SqlBulkCopy 作为一次执行多个INSERT的方法但由于某种原因，我在运行 WriteToServer(DataTable) 时遇到了一个唯一的约束违规 . 关于这个 SqlException 的奇怪之处在于它是这么说的 .

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 中分配列名时混淆了列名，但是我多次检查它们并且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;
    }
}

enter image description here

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

编辑：我刚刚更改了我的架构，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，而是程序中的问题 .

c# sql-server

2 回答

  • 0

    因为您有一个标识列，所以批量插入正在尝试将 nameColumn 插入 ID （并忽略它，因为该列是标识列）并且 bulkInsertIDColumn 在 Name 中 . 只需在插入中添加以下内容即可告诉它转到正确的列 .

    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);
}

    另一个选项是将 ID 列添加到 table ，并且不要在其中添加任何值 .

    DataColumn idColumn = new DataColumn("ID");

DataColumn nameColumn = new DataColumn("Name");
//nameColumn.Unique = true; //SqlBulkCopy does not care about these settings.
//nameColumn.AllowDBNull = false;

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

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

foreach (string productName in productNames)
{
    DataRow row = table.NewRow();
    //We don't do anything with row[idColumn]
    row[nameColumn] = productName;
    row[bulkInsertIDColumn] = bulkInsertID;
    table.Rows.Add(row);
}
    回复于
  • 2

    看起来它正在为列 BulkInsertID 抛出 UNIQUE 约束违规但是从已发布的表格模式中标记有该约束并且在您的代码中我看到您有 bulkInsertIDColumn.Unique = false; . 你确定你没有把它设置到其他任何地方 true .

    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一个 Random() 的新实例，如下面所示的尖代码块

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

    在 generateID() 中，您正在创建Random类的新实例

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

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