converting resultset from OleDbDataReader into list
Consider a Winforms app connecting to a SQL Server 2008 database and running a SQL SELECT
statement:
string myConnectionString = "Provider=SQLO开发者_运维百科LEDB;Data Source=hermes;Initial Catalog=qcvaluestest;Integrated Security=SSPI;";
string mySelectQuery = "SELECT top 500 name, finalconc from qvalues where rowid between 0 and 25000;";
OleDbConnection myConnection = new OleDbConnection(myConnectionString);
OleDbCommand myCommand = new OleDbCommand(mySelectQuery, myConnection);
myCommand.Connection.Open();
OleDbDataReader myReader = myCommand.ExecuteReader(CommandBehavior.CloseConnection);
How can you read the results of the query into a list?
Assume you have defined a class that is something like
class MyData
{
public string Name {get; set;}
public int FinalConc {get; set;} // or whatever the type should be
}
You would iterate through the results of your query to load a list.
List<MyData> list = new List<MyData>();
while (myReader.Read())
{
MyData data = new MyData();
data.Name = (string)myReader["name"];
data.FinalConc = (int)myReader["finalconc"]; // or whatever the type should be
list.Add(data);
}
// work with the list
If you just need one of the given fields, you can forego the class definition and simply have a List<T>
, where T
is the type of whatever field you want to hold.
You can try something as (adapt it for your convenience):
public class Person
{
public string Name { get; set; }
public int Age { get; set; }
}
List<Person> dbItems = new List<Person>();
while(myReader.Read())
{
Person objPerson = new Person();
objPerson.Name = Convert.ToString(myReader["Name"]);
objPerson.Age = Convert.ToInt32(myReader["Age"]);
dbItems.Add(objPerson);
}
List of what? Do you have a class setup that has properties for name
and finalconc
? Saying you do, and it looks like this:
public class QueryResult
{
public string Name { get; set; }
//not sure what finalconc type would be, so here just using string
public string FinalConc { get; set; }
}
Then you would do something like this:
var queryResults = new List<QueryResult>();
using(var myReader = myCommand.ExecuteReader())
{
while(myReader.Read())
{
queryResults.Add(new QueryResult
{
Name = myReader.GetString(myReader.GetOrdinal("name")),
FinalConc = myReader.GetString(myReader.GetOrdinal("finalconc"))
});
}
}
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