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tomato-magnet-regulato
Asked:2022-08-10 18:21:03 +0000 UTC2022-08-10 18:21:03 +0000 UTC

更新sql - c#添加到表+1中的数字

  • 772

危险代码：

using(var con = new SqlConnection(connection))
                {
                    con.Open();
                    string update = "update [DataBase] set [count] = [count]+ 1 where [id] = @id'";
                    using (var comm = new SqlCommand(update, con))
                    {
                        /* ------ */
                    }
                }

你能给我解释一下吗。SELECT如果我想在条件下显示某些东西，我理解使用：

string show = $"select name from DataBase where ID = '{id}'";
            using (var con = new SqlConnection(connection))
            using (var comm = new SqlCommand())
            {
                con.Open();
                comm.Connection = con;
                comm.CommandText = show;
                using(var reader = comm.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        CB.Items.Add(reader[0].ToString()); 
                    }
                }
            }

我什至学会了如何使用INSERT——通过 SQL server 中的存储过程。但我完全不知道如何int通过 ID 简单地通过 C#（上面的代码）添加到类型表 + 1。

using(var con = new SqlConnection(connection))
                    {
                        con.Open();
                        string update = $"update [DataBase] set [count] = [count]+ 1 where [id] = '{id(параметр метода, например)}'";
                        using (var comm = new SqlCommand(update, con))
                        {
                            /* ------ */
                        }
                    }

我有什么：

private void update(string table_number)
        {
            using(var con = new SqlConnection(connection))
            {
                con.Open();
                string update = $"update DataBase set count = count + 1 where id = '{table_number}'";
                using (var comm = new SqlCommand(update, con))
                {                    
                    comm.ExecuteNonQuery();                    
                }
            }
        }
c# sql-server

1 个回答

  1. Best Answer

    数据库中一个典型的 SQL 查询示例增加 1

    var connectionString = @"Data Source=.\SQLEXPRESS;Initial Catalog=usersdb;Integrated Security=True";
var sqlQuery = "UPDATE DataBase SET count += 1 WHERE id = '*someId*'";
     
using (var connection = new SqlConnection(connectionString))
{
    connection.Open();
    var command = new SqlCommand(sqlQuery, connection);
    int addRowsCount = command.ExecuteNonQuery();
    Console.WriteLine("Обновлено строк: {0}", addRowsCount);
}

    以一种友好的方式，值得以参数化查询的形式稍微调整一下。它更安全。它看起来像这样：

    var connectionString = @"Data Source=.\SQLEXPRESS;Initial Catalog=usersdb;Integrated Security=True";
var sqlQuery = "UPDATE DataBase SET count += 1 WHERE id = @id";
     
using (var connection = new SqlConnection(connectionString))
{
    connection.Open();
    var command = new SqlCommand(sqlQuery, connection);
    var id = new SqlParameter("@id", *someId*);
    command.Parameters.Add(id);
    int addRowsCount = command.ExecuteNonQuery();
    Console.WriteLine("Обновлено строк: {0}", addRowsCount);
}
    • 2

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