从 gridview 插入数据时处理 'NULL' 和键约束

Question

我正在尝试通过 C# Windows 应用程序中的 gridview 将值插入到数据库中。我尝试了两种不同的方法，但似乎都不适合我。 2种代码如下所示......

假设，即使下面的代码有效......我收到关于主键和外键约束的各种错误......

问题：

我有 confactorID 和 macroID 列作为整数，在目标中可以为空 businesslogic table.......我是不确定如何从 C# gridview 工具在这些列中插入 'NULL'...
即使我将整数值作为输入，也似乎存在外键和主键（重复）约束问题....

我需要在下面的代码中更改什么来解决这些问题....我已经被这些问题困扰了 8 个多小时...非常感谢任何帮助。

代码类型 1：

    private void ADD_button_Click(object sender, EventArgs e)
    {
        try
        {
            using (SqlConnection con = new SqlConnection(sqlconn))
            {
                using (SqlCommand cmd = new SqlCommand())
                {
                    cmd.Connection = con;
                    con.Open();

                    for (int i = 1; i < dataGridView.Rows.Count; i++)
                    {
                        string sql = @"INSERT INTO " + schemaName +"ERSBusinessLogic VALUES ("
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_ID"].Value + ", '"
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_Formula"].Value.ToString() + "', "
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_InputsCount"].Value + ",'"
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_Inputs"].Value.ToString() + "', "
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_ConvFactorID"].Value + ", "
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_MacroID"].Value + ", '"
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_DataSeries"].Value.ToString() + "', '"
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_InputTimeDimensionValue"].Value.ToString() + "', "
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_InputTimeDimensionType"].Value + ", "
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_GeographyDimensionID"].Value + ", "
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_InputsUnitsIDs"].Value + ", '"
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_Type"].Value + "', "
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_PrivacyID"].Value + ", '"
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_LongDesc"].Value.ToString() + "', '"
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_InputSources"].Value.ToString() + "', '"
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_OutputName"].Value.ToString() + "', "
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_OutputUnitID"].Value + ", '"
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_OutputDestination"].Value.ToString() + "', '"
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_OutputTimeDimensionValue"].Value.ToString() + "', "
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_OutputTimeDimensionType"].Value + ", "
                                        + dataGridView.Rows[i].Cells["ERSBusinessLogic_GroupID"].Value + ");";

                         if ((dataGridView.Rows[i].Cells["ERSBusinessLogic_ConvFactorID"].Value == " ") && (dataGridView.Rows[i].Cells["ERSBusinessLogic_MacroID"].Value == null))
                         {
                             Convert.ToInt32(dataGridView.Rows[i].Cells["ERSBusinessLogic_ConvFactorID"].Value = "NULL");
                             Convert.ToInt32 (dataGridView.Rows[i].Cells["ERSBusinessLogic_MacroID"].Value = "NULL");

                             cmd.CommandText = sql;
                             cmd.ExecuteNonQuery();
                         }
                         else
                         {
                             cmd.CommandText = sql;
                             cmd.ExecuteNonQuery();
                         }
                     }
                 }
             }
        }
        catch (Exception ex)
        {
            MessageBox.Show("Error : " + ex.Message);
        }
        finally
        {
            con.Close();
        }
    }

代码类型 2：

private void ADD_button_Click(object sender, EventArgs e)
{
    // Getting data from DataGridView
    DataTable myDt = new DataTable();
    myDt = GetDTfromDGV(dataGridView);

    // Writing to sql
    WriteToSQL(myDt);
}

private DataTable GetDTfromDGV(DataGridView dgv)
{
    // Making our DataTable
    DataTable dt = new DataTable();

    foreach (DataGridViewColumn column in dgv.Columns)
    {
        dt.Columns.Add(column.Name, typeof(string));
    }

    // Getting data
    foreach (DataGridViewRow dgvRow in dgv.Rows)
    {
        DataRow dr = dt.NewRow();

        for (int col = 0; col < dgv.Columns.Count; col++)
        {
            dr[col] = dgvRow.Cells[col].Value;
        }

        dt.Rows.Add(dr);
    }

    // removing empty rows
    for (int row = dt.Rows.Count - 1; row >= 0; row--)
    {
        bool flag = true;

        for (int col = 0; col < dt.Columns.Count; col++)
        {
            if (dt.Rows[row][col] != DBNull.Value)
            {
                flag = false;
                break;
            }
        }

        if (flag == true)
        {
            dt.Rows.RemoveAt(row);
        }
    }

    return dt;
}

private void WriteToSQL(DataTable dt)
{
    using (SqlConnection con = new SqlConnection(sqlconn))
    {
        SqlBulkCopy sqlBulkCopy = new SqlBulkCopy(con);
        // Setting the database table name
        sqlBulkCopy.DestinationTableName = "[AnimalProductsCoSD].[CoSD].[ERSBusinessLogic]";
        // Mapping the DataTable columns with that of the database table
        Convert.ToInt32 (sqlBulkCopy.ColumnMappings.Add(dt.Columns[0].ColumnName, "ERSBusinessLogic_ID"));
       Convert.ToString(sqlBulkCopy.ColumnMappings.Add(dt.Columns[1].ColumnName, "ERSBusinessLogic_Formula"));
       Convert.ToInt32 (sqlBulkCopy.ColumnMappings.Add(dt.Columns[2].ColumnName, "ERSBusinessLogic_InputsCount"));
        Convert.ToString (sqlBulkCopy.ColumnMappings.Add(dt.Columns[3].ColumnName, "ERSBusinessLogic_Inputs"));
        Convert.ToInt32 (sqlBulkCopy.ColumnMappings.Add(dt.Columns[4].ColumnName, "ERSBusinessLogic_ConvFactorID"));
        Convert.ToInt32 (sqlBulkCopy.ColumnMappings.Add(dt.Columns[5].ColumnName, "ERSBusinessLogic_MacroID"));

        Convert.ToString (sqlBulkCopy.ColumnMappings.Add(dt.Columns[6].ColumnName, "ERSBusinessLogic_DataSeries"));
        Convert.ToString (sqlBulkCopy.ColumnMappings.Add(dt.Columns[7].ColumnName, "ERSBusinessLogic_InputTimeDimensionValue"));
        Convert.ToInt32 (sqlBulkCopy.ColumnMappings.Add(dt.Columns[8].ColumnName, "ERSBusinessLogic_InputTimeDimensionType"));
        Convert.ToInt32 (sqlBulkCopy.ColumnMappings.Add(dt.Columns[9].ColumnName, "ERSBusinessLogic_GeographyDimensionID"));
        Convert.ToInt32 (sqlBulkCopy.ColumnMappings.Add(dt.Columns[10].ColumnName, "ERSBusinessLogic_InputsUnitsIDs"));
        Convert.ToString (sqlBulkCopy.ColumnMappings.Add(dt.Columns[11].ColumnName, "ERSBusinessLogic_Type"));

        Convert.ToInt32 (sqlBulkCopy.ColumnMappings.Add(dt.Columns[12].ColumnName, "ERSBusinessLogic_PrivacyID"));
        Convert.ToString (sqlBulkCopy.ColumnMappings.Add(dt.Columns[13].ColumnName, "ERSBusinessLogic_LongDesc"));
        Convert.ToString (sqlBulkCopy.ColumnMappings.Add(dt.Columns[14].ColumnName, "ERSBusinessLogic_InputSources"));
        Convert.ToString (sqlBulkCopy.ColumnMappings.Add(dt.Columns[15].ColumnName, "ERSBusinessLogic_OutputName"));
        Convert.ToInt32 (sqlBulkCopy.ColumnMappings.Add(dt.Columns[16].ColumnName, "ERSBusinessLogic_OutputUnitID"));
        Convert.ToString (sqlBulkCopy.ColumnMappings.Add(dt.Columns[17].ColumnName, "ERSBusinessLogic_OutputDestination"));

        Convert.ToString (sqlBulkCopy.ColumnMappings.Add(dt.Columns[18].ColumnName, "ERSBusinessLogic_OutputTimeDimensionValue"));
        Convert.ToInt32 (sqlBulkCopy.ColumnMappings.Add(dt.Columns[19].ColumnName, "ERSBusinessLogic_OutputTimeDimensionType"));
        Convert.ToInt32 (sqlBulkCopy.ColumnMappings.Add(dt.Columns[20].ColumnName, "ERSBusinessLogic_GroupID"));

        con.Open();
        sqlBulkCopy.WriteToServer(dt);
    }
}

谢谢

Answer 1

您可以使用参数化查询。例如：

            var sqlcommand = new SqlCommand
            {
                CommandText = "INSERT INTO TABLE(Column1,Column2) VALUES(@Column1Value,@Column2Value)"
            };
            var param1 = new SqlParameter("@Column1Value", SqlDbType.Int)
            {
                Value = (String.IsNullOrWhiteSpace(dataGridView.Rows[i].Cells["ERSBusinessLogic_ConvFactorID"].Value)) ? DBNull.Value: (object)(dataGridView.Rows[i].Cells["ERSBusinessLogic_ConvFactorID"].Value) 
            };
            var param2 = new SqlParameter("@Column2Value", SqlDbType.Int)
            {
                Value = (String.IsNullOrWhiteSpace(dataGridView.Rows[i].Cells["ERSBusinessLogic_MacroID"].Value)) ?  DBNull.Value : (object)dataGridView.Rows[i].Cells["ERSBusinessLogic_MacroID"].Value) 
            };
            sqlcommand.Parameters.Add(param1);
            sqlcommand.Parameters.Add(param2);

Answer 2

如果您使用尝试过的方法 1，您可能需要创建 SqlParameter 对象并参数化您的查询。请参阅此 SO post: Right syntax of SqlParameter. That being said, you just want to get it to work first I'm sure. You could check the value of the DataGridViewCell's Value property for the convFactorID and macroID. If either of these are null, then you can assign a string the text "NULL". For brevity, I've used the C# conditional operator (https://msdn.microsoft.com/en-us/library/ty67wk28.aspx)。这是您可以执行我所描述的操作的一种方式：

string convFactorIDText = (dataGridView.Rows[i].Cells["ERSBusinessLogic_ConvFactorID"].Value == null) ? "NULL" : dataGridView.Rows[i].Cells["ERSBusinessLogic_ConvFactorID"].Value.ToString();
string macroIDText = (dataGridView.Rows[i].Cells["ERSBusinessLogic_MacroID"].Value == null) ? "NULL" : dataGridView.Rows[i].Cells["ERSBusinessLogic_MacroID"].Value.ToString();

然后改变你 SQL 以包含包含实际值或 NULL 的字符串变量。

string sql = string.Format(@"INSERT INTO {0}.ERSBusinessLogic VALUES ({1}, '{2}', {3}, {4}, {5}, {6}"), 
    schemaName,
    dataGridView.Rows[i].Cells["ERSBusinessLogic_ID"].Value,
    dataGridView.Rows[i].Cells["ERSBusinessLogic_Formula"].Value.ToString(),
    dataGridView.Rows[i].Cells["ERSBusinessLogic_InputsCount"].Value,
    dataGridView.Rows[i].Cells["ERSBusinessLogic_Inputs"].Value,
    convFactorIDText,
    macroIDText
    // and so forth
);

Answer 3

首先检查您的数据库 table，保留来自另一个 table 的 ID 的列必须允许空值，如下所示：

如果你的table ID是自动递增的Identity列你不需要写ID，table会自动添加ID。

如果一切正常，请尝试这样做：

private DataTable GetDTfromDGV(DataGridView dgv)
    {
        // Macking our DataTable
        DataTable dt = new DataTable();
        //Another way to add columns
        dt.Columns.AddRange(new DataColumn[5]
            {
                //new DataColumn("table_ID", typeof(string)), if table_ID is not Identity column with auto increment then uncomment
                new DataColumn("sql_col2", typeof(string)),
                new DataColumn("sql_col3", typeof(string)),
                new DataColumn("sql_col4", typeof(string)),
                new DataColumn("Table_2_ID", typeof(int)),
                new DataColumn("Table_3_IDt", typeof(int))
            });
        // Getting data
        foreach (DataGridViewRow dgvRow in dgv.Rows)
        {
            DataRow dr = dt.NewRow();
            for (int col = 1; col < dgv.Columns.Count; col++) //if table_ID is not Identity column with auto increment then start with 0
            {
                dr[col - 1] = dgvRow.Cells[col].Value == null ? DBNull.Value : dgvRow.Cells[col].Value;
            }
            dt.Rows.Add(dr);
        }
        // removing empty rows
        ....
        return dt;
    }
    private void WriteToSQL(DataTable dt)
    {
        string connectionStringSQL = "Your connection string";
        using (SqlConnection sqlConn = new SqlConnection(connectionStringSQL))
        {
            SqlBulkCopy sqlBulkCopy = new SqlBulkCopy(sqlConn);
            // Setting the database table name
            sqlBulkCopy.DestinationTableName = "Table_1";
            // Mapping the DataTable columns with that of the database table
            //sqlBulkCopy.ColumnMappings.Add(dt.Columns[0].ColumnName, "table_ID"); table_ID is Identity column with auto increment
            sqlBulkCopy.ColumnMappings.Add(dt.Columns[0].ColumnName, "sql_col2");
            sqlBulkCopy.ColumnMappings.Add(dt.Columns[1].ColumnName, "sql_col3");
            sqlBulkCopy.ColumnMappings.Add(dt.Columns[2].ColumnName, "sql_col4");
            sqlBulkCopy.ColumnMappings.Add(dt.Columns[3].ColumnName, "Table_2_ID");
            sqlBulkCopy.ColumnMappings.Add(dt.Columns[4].ColumnName, "Table_3_ID");
            sqlConn.Open();
            sqlBulkCopy.WriteToServer(dt);
        }
    }

我试过了，这就是我得到的：

从 gridview 插入数据时处理 'NULL' 和键约束

Handling 'NULL' and key constraints when inserting data from a gridview

c#

.net

winforms

datagridview

windows-applications