将List <string>传递给SQL参数

Question

该程序在C#中,我正在尝试传递List<string>一个参数.

List<string> names = new List<string>{"john", "brian", "robert"};

在纯SQL中,查询将如下所示:

DELETE FROM Students
WHERE name = 'john' or name = 'brian' or name = 'robert'

在C#代码中运行SQL命令时,我知道正确的方法是使用参数而不是将所有内容连接成一个巨大的字符串.

command.CommmandText = "DELETE FROM Students WHERE name = @name";
command.Parameters.Add(new MySqlParameter("@name", String.Format("'{0}'", String.Join("' or name = '", names)));
command.NonQuery();

上述方法不起作用.它没有抛出任何错误/异常,它只是根本不按我想要的方式工作.

我应该怎么做呢？

我想过循环遍历List<string>并只执行每一个名字.

foreach(string name in names)
{
    command.CommmandText = "DELETE FROM Students WHERE name = @name";
    command.Parameters.Add(new MySqlParameter("@name", name));
    command.NonQuery();
    command.Parameters.Clear();
}

但这需要很长时间,因为实际List<string>情况非常大.我想尝试尽可能少地执行.

谢谢!

Answer 1

您可以在IN子句中参数化列表中的每个值:

List<string> names = new List<string> { "john", "brian", "robert" };
string commandText = "DELETE FROM Students WHERE name IN ({0})";
string[] paramNames = names.Select(
    (s, i) => "@tag" + i.ToString()
).ToArray();

string inClause = string.Join(",", paramNames);
using (var command = new SqlCommand(string.Format(commandText, inClause), con))
{
    for (int i = 0; i < paramNames.Length; i++)
    {
        command.Parameters.AddWithValue(paramNames[i], names[i]);
    }
    int deleted = command.ExecuteNonQuery();
} 

这类似于:

"... WHERE Name IN (@tag0,@tag1,@tag2)"

command.Parameters["@tag0"].Value = "john";
command.Parameters["@tag1"].Value = "brian";
command.Parameters["@tag2"].Value = "robert";

改编自:https://stackoverflow.com/a/337792/284240