如何生成列表 从SQL查询？(How to generate List fro

如果我有一个DbCommand规定执行是这样的：

SELECT Column1 FROM Table1

什么是生成的最好方法List<String>返回的记录？

没有LINQ的等，我使用VS2005。

Answer 1:

我认为这是你在找什么。

List<String> columnData = new List<String>();

using(SqlConnection connection = new SqlConnection("conn_string"))
{
    connection.Open();
    string query = "SELECT Column1 FROM Table1";
    using(SqlCommand command = new SqlCommand(query, connection))
    {
        using (SqlDataReader reader = command.ExecuteReader())
        {
            while (reader.Read())
            {
                columnData.Add(reader.GetString(0));
            }         
        }
    }
}

没测试过，但是这个应该工作正常。

Answer 2:

遍历项目，并添加到集合。 您可以使用Add方法

List<string>items=new List<string>();
using (var con= new SqlConnection("yourConnectionStringHere")
{
    string qry="SELECT Column1 FROM Table1";
    var cmd= new SqlCommand(qry, con);
    cmd.CommandType = CommandType.Text;
    con.Open();
    using (SqlDataReader objReader = cmd.ExecuteReader())
    {
        if (objReader.HasRows)
        {              
            while (objReader.Read())
            {
              //I would also check for DB.Null here before reading the value.
               string item= objReader.GetString(objReader.GetOrdinal("Column1"));
               items.Add(item);                  
            }
        }
    }
}

Answer 3:

或嵌套表（还行，OP是单个列，这是一个多列。）：

        //Base list is a list of fields, ie a data record
        //Enclosing list is then a list of those records, ie the Result set
        List<List<String>> ResultSet = new List<List<String>>();

        using (SqlConnection connection =
            new SqlConnection(connectionString))
        {
            // Create the Command and Parameter objects.
            SqlCommand command = new SqlCommand(qString, connection);

            // Create and execute the DataReader..
            connection.Open();
            SqlDataReader reader = command.ExecuteReader();
            while (reader.Read())
            {
                var rec = new List<string>();
                for (int i = 0; i <= reader.FieldCount-1; i++) //The mathematical formula for reading the next fields must be <=
                {                      
                    rec.Add(reader.GetString(i));
                }
                ResultSet.Add(rec);

            }
        }

Answer 4:

如果您想查询所有列

List<Users> list_users = new List<Users>();
MySqlConnection cn = new MySqlConnection("connection");
MySqlCommand cm = new MySqlCommand("select * from users",cn);
try
{
    cn.Open();
    MySqlDataReader dr = cm.ExecuteReader();
    while (dr.Read())
    {
        list_users.Add(new Users(dr));
    }
}
catch { /* error */ }
finally { cn.Close(); }

用户的构造函数会做所有的“dr.GetString（I）”

Answer 5:

当返回的数据是一个字符串; 你可以转换为不同的数据类型：

(from DataRow row in dataTable.Rows select row["columnName"].ToString()).ToList();

文章来源: How to generate List from SQL query?