CODEWITHSUNDEEP
c#stringlistnpgsql
Imants Volkovs
Imants Volkovs

Reputation: 836

C# - store data from database in 2 column list

    public static List<string>[] ColumnToList2(string table, List<string>[]data, NpgsqlConnection ncon)
    {
        using (ncon)
        {
            NpgsqlDataAdapter da = new NpgsqlDataAdapter("SELECT id, name FROM " + table + "", ncon);
            DataSet ds = new DataSet();
            da.Fill(ds, "" + table + "");
            foreach (DataRow row in ds.Tables["" + table + ""].Rows)
            {
                //Testing area
                //Console.WriteLine(row["id"].ToString());
                //Console.WriteLine(row["name"].ToString());

                data[0].Add(row[0].ToString());
                data[1].Add(row[1].ToString());                    
            }
        }
        return data;
    }

Hello again! This time i want to ask advice for searching id from value, then storing both columns in list array. When i test input in console there is what i want, but when try to see after input in list, there isnt the resut i wanted (id name - list) Here goes definition of variables:

        List<string>[] data_array = new List<string>[];
        datu_array[0]=new List<string>();
        datu_array[1]=new List<string>();

When i try to see output through console, there is and error - that i havent defined array size

I hope u can help me solve this problem, thanks in advance.

Upvotes: 0

Views: 3320

Answers (3)

sparkyShorts
sparkyShorts

Reputation: 630

From what I understood from your question, I would suggest that you use a dictionary instead of a List of string arrays.

Upvotes: 1

Tim Schmelter
Tim Schmelter

Reputation: 460228

I assume that you actually want a List<string[]> instead of List<string>[]. So one list and for every row a string[] with all columns as strings.

You could use LINQ:

List<string[]> data = ds.Tables[0].AsEnumerable()
 .Select(row => row.ItemArray
    .Select(col => col.ToString())
    .ToArray())
 .ToList();

But why don't you stay with the DataTable which has some advantages over the list, for example the columns which you can either access via ordinal index or via name.

Upvotes: 1

Jonesopolis
Jonesopolis

Reputation: 25370

Arrays need to be assigned a size when they are instantiated:

List<string>[] data_array = new List<string>[2];

Upvotes: 4

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