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Refering to view values one by one

I have the following code which establishing an SQL connection inside of a project I am working on. What I want to do is to create a for loop which contains a method and every time the loop repeats the method runs with a different value until all views of the returned query are used.
I can't figure out how to refer to every value of the view without saving the view to a list or an array first. Any ideas?
SqlConnection Con = new SqlConnection(#"Data Source=localhost\**;Initial Catalog=ML;User Id=sa;Password='**'");
string sql = #"select product_id,Name from E_PRODUCT_PROPERTY";
var mylist = new List<WineRating>();
using (var command = new SqlCommand(sql, Con))
{
Con.Open();
using (var reader = command.ExecuteReader())
{
while (reader.Read())
new WineRating { product_id = reader.GetInt32(0), Name = reader.GetString(1) };
///Here goes the code I suppose
method_name(reader.GetInt32(0), reader.GetString(1));
}
}
public static int method_name(int product_id, string Name)
{
int num = x *2;
Console.WriteLine(num + Name);
}

Perhaps like this:
using (var reader = command.ExecuteReader())
{
while (reader.Read())
{
MyMethodToPrintToScreen(reader.GetInt32(0), reader.GetString(1));
}
}
With the method to print to screen
private static void MyMethodToPrintToScreen(int id, string product)
{
//Do whatever you wish with the data: example
Console.WriteLine($"My id: {id} | Product: {product}");
}
Edit
Let me make it even more obvious(using your exact code):
SqlConnection Con = new SqlConnection(#"Data Source=localhost\**;Initial Catalog=ML;User Id=sa;Password='**'");
string sql = #"select product_id,Name from E_PRODUCT_PROPERTY";
var mylist = new List<WineRating>();
using (var command = new SqlCommand(sql, Con))
{
Con.Open();
using (var reader = command.ExecuteReader())
{
while (reader.Read())
{
method_name(reader.GetInt32(0), reader.GetString(1));
}
}
}

how to add values from database to a list in unity

i have a data base in which i created a table
"CampWheelDenominationno", i have a specific row "quota"
i need to take the "slno" of corresponding "quota" when ever "quota"
becomes zero.
my sql code to do that is
"select slno from CampWheelDenomination where quota_allowded = 0"
now i need to add these "slno" to a list..i have done a method my own but t doesn't works
public int checkCodeinDb()
{
using (IDbConnection dbConnection = new SqliteConnection (connectionString))
{
dbConnection.Open ();
using (IDbCommand dbCmd = dbConnection.CreateCommand ())
{
string sqlQuery = "select slno from CampWheelDenomination where quota_allowded = 0";
dbCmd.CommandText = sqlQuery;
using (IDataReader reader = dbCmd.ExecuteReader ())
{
while (reader.Read ())
{
//slnolist is a list i have created at begining
SlNoList.Add (reader.GetString (0));
}
return slnolist ; //error at here
foreach (string st in SlNoList)// i have done this to check whether the slno is added to the list.
{
print (st);
}
dbConnection.Close ();
reader.Close ();
}
}
}
}
how to add these slno from the databse to the SlNOList
error is Cannot implicitly convert type System.Collections.Generic.List<string>' toint' occuring at line return SlNoList

Your are trying to trying to return List but you function return type is int. Change you function definition as follows:
public List<string> checkCodeinDb()
{
///your usual code here
Also looking at your code you probably should have a List inside your function and return it.
Example:
List<string> slnolist = checkCodeinDb();
public List<string> checkCodeinDb()
{
List<string> data;
///your usual code here and add your database returned value to data variable and finally return it
return data;
}

and also to add the values from database to list we can use this code
public void checkCodeinDb()
{
using (IDbConnection dbConnection = new SqliteConnection (connectionString))
{
dbConnection.Open ();
using (IDbCommand dbCmd = dbConnection.CreateCommand ())
{
string sqlQuery = "select slno from CampWheelDenomination where quota_allowded = 0";
dbCmd.CommandText = sqlQuery;
using (IDataReader reader = dbCmd.ExecuteReader ())
{
while (reader.Read ())
{
string ad = reader ["slno"].ToString();
SlNoList.Add (ad);
}
foreach (string st in SlNoList)
{
print (st);
}
dbConnection.Close ();
reader.Close ();
}
}
}
}

Must declare the scalar variable in Select command

I am passing a long list of employeeIds to employeeIdlist and I split them into a List. Using this list I am adding parameters to my query.
I am getting the following error
{"Must declare the scalar variable \"#EmployeeId\"."}
public List<versionInfo> GetVersion(string employeeIdlist)
{
DbHelper helper = new DbHelper();
List<versionInfo> empVerInfo = new List<versionInfo>();
using (SqlConnection conn = new SqlConnection(connString))
{
conn.Open();
using (SqlCommand getVersion = new SqlCommand())
{
getVersion.Connection = conn;
getVersion.CommandText = #"SELECT EmployeeId,Version
FROM [dbo].[EmployeeVersion]
WHERE EmployeeId in (#EmployeeId)";
getVersion.CommandType = CommandType.Text;
List<int> empIds = employeeIdlist.Split(',').Select(int.Parse).ToList();
StringBuilder sb = new StringBuilder();
int i = 0;
foreach (var emp in empIds)
{
// IN clause
sb.Append("#EmployeeId" + i.ToString() + ",");
// parameter
getVersion.Parameters.AddWithValue("#EmployeeId" + i.ToString(), emp);
i++;
}
// getVersion.Parameters.AddWithValue("#EmployeeId", employeeIdlist);
SqlDataReader rdr = getVersion.ExecuteReader();
while (rdr.Read())
{
versionInfo vi = new versionInfo();
vi.employeeId = helper.GetDb<int>(rdr, "EmployeeId");
vi.version = helper.GetDb<decimal>(rdr, "Version");
empVerInfo.Add(vi);
}
rdr.Close();
}
conn.Close();
}
return empVerInfo;
}

Remove the text after the IN
getVersion.CommandText = #"SELECT EmployeeId,Version
FROM [dbo].[EmployeeVersion]
WHERE EmployeeId in (";
then the foreach could build the full list of parameters and texts
foreach (var emp in empIds)
{
sb.Append("#EmployeeId" + i.ToString() + ",");
getVersion.Parameters.AddWithValue("#EmployeeId" + i.ToString(), emp);
i++;
}
after exiting the loop remove the last comma from the StringBuilder
sb.Length--;
finally, complete the command text appending the content of the StringBuilder and do not forget the closing parenthesys for the IN clause.
getVersion.CommandText += sb.ToString() + ")";
Now you can run the command with the correct IN clause and a matching list of parameters

If fails because your string query has one parameter named #EmployeeId and your Command object has many parameters with different names ("#EmployeeId1" is not equal to "#EmployeeId")
It seems like you are trying to apply this approach, which is a good idea.
You are two lines away of getting it to work:
Add this lines:
sb.Lenght--;
getVersion.CommandText = getVersion.CommandText.Replace("#EmployeeId",sb.ToString())
just before:
SqlDataReader rdr = getVersion.ExecuteReader();
After doing that your added parameters will match those #parameters existing in the sql string.

This is just another option. You can achieve the same result in 3 lines of code using Dapper ORM used in Stack Overflow.
You can download via NuGet.
public class VersionInfo
{
public int EmployeeId { get; set; }
public decimal Version { get; set; }
}
class Program
{
public static string connString = "...";
static void Main(string[] args)
{
var result = GetVersion(new List<int> {1, 2});
Console.ReadLine();
}
public static List<VersionInfo> GetVersion(IList<int> employeeIds)
{
using (IDbConnection conn = new SqlConnection(connString))
{
conn.Open();
var entities = conn.Query<VersionInfo>(
#"SELECT EmployeeId, Version from EmployeeVersion WHERE EmployeeId IN #EmployeeIds",
new {EmployeeIds = employeeIds});
return entities.ToList();
}
}
}

On your select statement you have to declare a value for your variable. I have made it an Integer. If it is a text value, then you can use varchar(25).
#"DECLARE #EmployeeId INT
SELECT EmployeeId,Version
FROM [dbo].[EmployeeVersion]
WHERE EmployeeId in (#EmployeeId)";

How to add item to a list<object> from database in C#?

I'm creating a list <object> and here I'm adding my data from a database.
But I totally don't know how to deal with a list <object>.
public class ClassList
{
public int Name { get; set; }
public string Birthday { get; set; }
}
private void GetClassList()
{
SqlConnection conn = new SqlConnection(GlobalVar.ConnString);
SqlCommand cmd = new SqlCommand
("SELECT * " +
"FROM Class_Data ", conn);
conn.Open();
SqlDataReader dr = cmd.ExecuteReader();
try
{
List<ClassList> ClassList = new List<ClassList>();
while (dr.Read())
{
ClassList.Add(new ClassList()
{
Name = ___?___, //what should i write here
Birthday = ___?___ //and here
});
}
}
catch{}
finally
{
dr.Close();
conn.Close();
}
}
Having been looking for lots of information but still fail to work it out.
I will be very appreciated if someone could help!

This should do it:
List<ClassList> ClassList = new List<ClassList>();
while (dr.Read())
{
ClassList.Add(new ClassList()
{
Name = (int)dr["Name"], //the name of the db column
Birthday = dr["Birthday"].ToString();
});
}
As a side note, it maybe worth altering your query from SELECT *... to just selecting the columns you require, from readability/maintenance point of view.
Also, is Name really an int seems like it could be a string.
You can also refer to the documentation:
SqlDataReader.Item Property (String)

You can use column name that are return by your database query with dr like dr["ColumnName"]
ClassList.Add(new ClassList()
{
Name = dr["NameColum"], //what should i write here
Birthday = dr["BrithColum"] //and here
});

Something like that:
// You don't use "this" in the context
// It seems, that you want to return the collected data (List<ClassList>)
private static List<ClassList> GetClassList() {
// Put IDisposable into using
using (SqlConnection conn = new SqlConnection(GlobalVar.ConnString)) {
conn.Connect();
// You want to fetch two fields only, right? Not the entire table (*)
String sql =
#"select Name,
BirthDay
from Class_Data"
using (SqlCommand cmd = new SqlCommand(sql, conn)) {
List<ClassList> result = new List<ClassList>();
using (SqlDataReader dr = cmd.ExecuteReader()) {
while (dr.Read()) {
result.Add(new ClassList() {
Name = Convert.ToString(dr[0]),
Birthday = Convert.ToDateTime(dr[1])
});
}
}
return result;
}
}
}

You can access the column values with dr["ColumnName"].

How to find particular value arraylist

I have one array list:
public ArrayList GetExpenseTypes()
{
ArrayList expArry = new ArrayList();
using (SqlConnection conn = new SqlConnection(connStr))
{
string sql = "SELECT ID, TITLE";
sql += " FROM EXPENSE_TYPE";
SqlCommand cmd = new SqlCommand(sql, conn);
SqlDataReader reader;
try
{
conn.Open();
reader = cmd.ExecuteReader();
while (reader.Read())
{
expArry.Add(new ListItem(reader["TITLE"].ToString(), reader["ID"].ToString()));
}
reader.Close();
}
catch (Exception ex)
{
}
finally
{
conn.Close();
}
}
return expArry;
}
My ArrayList like this
1 name1
2 name2
3 name3
4 name4
5 name6
if my value is 4 i need to display name4
How i achieve that?

Instead of ArrayList you might want to use Dictionary<string,string> like this.
public IDictionary<string,string> GetExpenseTypes()
{
Dictionary<string,string> expArry = new Dictionary<string,string>();
// Your sql code
while (reader.Read())
{
expArry.Add(reader["TITLE"].ToString(), reader["ID"].ToString());
}
// The rest of your code
}
Then you can get the value like this
var values = GetExpenseTypes();
string valueYouWant = values["4"];
If on the other hand your problem is that when you use the ListItems in a web control you are seeing the wrong values, then you need to swap the parameters when you create the ListItem because the first parameter is the text that is displayed and the second is the value. Like this.
expArry.Add(new ListItem(reader["ID"].ToString(), reader["TITLE"].ToString()));
In which case you should consider using a List<ListItem> instead of ArrayList

you could use BinarySearch method if you are searching for value types; in your case this does not seem possible.
I think you may need to use a loop assuming that you can not use Linq (because of the framework employed);
int index = -1;
for(int i=0; i<expArray.Count;i++)
{
ListItem temp = (expArray[i] as ListItem);
if(temp != null && temp.Value == "some value")
{
index = i;
break;
}
}

I'd recommend first changing ArrayList to List<ListItem>. If you can't do that for some reason you could use (assuming each item is unique):
var x = expArry.Cast<ListItem>().SingleOrDefault(exp => exp.Value == value);
if (x != null)
//item was found
If you know the item will always be there just use Single if it will only be there once.

Don't use ArrayList, do something like this using a generic dictionary
public IDictionary<int, string> GetExpenseTypes()
{
var result = new Dictionary<int, string>();
using (var conn = new SqlConnection(connStr))
{
var getExpenses = new SqlCommand(
"SELECT ID, TITLE FROM EXPENSE_TYPE",
conn);
conn.Open();
using (var reader = command.ExecureReader())
{
while (reader.Read())
{
result.Add(reader.GetInt32(0), reader.GetString(1));
}
}
}
return result;
}
Then you could look up your string like this
var type4 = GetExpenseTypes()[4];
alternatively, don't get the whole list to find one value.
public string GetExpenseType(int id)
{
using (var conn = new SqlConnection(connStr))
{
var getExpenseType = new SqlCommand(
"SELECT TITLE FROM EXPENSE_TYPE WHERE ID = #p0",
conn);
getExpenseType.Parameters.Add(id);
conn.Open();
return (string)getExpenseType.ExecuteScalar();
}
}
If, for some bad reason, you want to stick with your ArrayList returning function, you can find your item like this.
var expenseTypes = GetExpenseTypes().OfType<ListItem>().ToDictionary(
li => int.Parse(li.Text),
li => li.Value);
var type4 = expenseTypes[4];
or, if you want to do this once.
var type4 = GetExpenseTypes().OfType<ListItem>()
.Single(li => li.Text == "4").Value;