CODEWITHSUNDEEP
c#sqlite
black_belt
black_belt

Reputation: 6799

sqlite database connection class in C#

I am very new to C#, I am trying to create a sqlite database connection class. I have created a new class file by clicking on my project name> Add > Class. I have the following code in this file.

The problem is I am getting error in every lines after SQLiteDataReader

  1. If I hover over sqlite_conn then it says '... is a field but is used like a type'
  2. if I hover over SQLiteConnection then it says ... method must have a return type
  3. If I hover over ("Data Source=database.db;Version=3;New=True;Compress=True;") then it says Type expected

` 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Finisar.SQLite;

namespace learningCsharp
{
class database
{
    // We use these three SQLite objects:
    SQLiteConnection sqlite_conn;
    SQLiteCommand sqlite_cmd;
    SQLiteDataReader sqlite_datareader;

    // Getting error in every lines after this 

    // create a new database connection:
    sqlite_conn = new SQLiteConnection("Data Source=database.db;Version=3;New=True;Compress=True;");

   //open the connection:
     sqlite_conn.Open();

   // create a new SQL command:
     sqlite_cmd = sqlite_conn.CreateCommand();

}
}

Could you please help me to solve this problem and create a working sqlite database connection class?

Upvotes: 1

Views: 5920

Answers (4)

Bart Friederichs
Bart Friederichs

Reputation: 33491

You never create methods or constructors.

class database
{
    // Here you define properties: OK
    SQLiteConnection sqlite_conn;
    SQLiteCommand sqlite_cmd;
    SQLiteDataReader sqlite_datareader;


    // Then, you do stuff to them: NOT OK
    sqlite_conn = new SQLiteConnection("Data Source=database.db;Version=3;New=True;Compress=True;");

   //open the connection:
     sqlite_conn.Open();

   // create a new SQL command:
     sqlite_cmd = sqlite_conn.CreateCommand();

}
}

You could fix it, by putting your "doing-stuff" code in a method:

class database
{
    // Here you define properties: OK
    SQLiteConnection sqlite_conn;
    SQLiteCommand sqlite_cmd;
    SQLiteDataReader sqlite_datareader;

    void public DoStuff() {
       // Then, you do stuff to them: NOT OK
       sqlite_conn = new SQLiteConnection("Data Source=database.db;Version=3;New=True;Compress=True;");

      //open the connection:
      sqlite_conn.Open();

      // create a new SQL command:
      sqlite_cmd = sqlite_conn.CreateCommand();

    }
  }
}

Then, you can instantiate and run like this:

database db = new database();
db.DoStuff();

This is all basic C#, OO programming. I strongly advise you learn C# first, before getting into SQLite database programming.

Upvotes: 0

Damith
Damith

Reputation: 63065

You need to put the line in error in a class constructor or a method.

public class database
{
    // We use these three SQLite objects:
    public SQLiteConnection sqlite_conn;
    public SQLiteCommand sqlite_cmd;
    public SQLiteDataReader sqlite_datareader;

    public database()
    {
         sqlite_conn = new SQLiteConnection("Data Source=database.db;Version=3;New=True;Compress=True;");
         sqlite_conn.Open();
         sqlite_cmd = sqlite_conn.CreateCommand();
     }   

}

Upvotes: 1

andrewb
andrewb

Reputation: 3095

You need to instantiate the SQLiteDataReader class by something like

SQLiteDataReader reader = sqlite_cmd.ExecuteReader();

See http://zetcode.com/db/sqlitecsharp/read/

Upvotes: 0

gzaxx
gzaxx

Reputation: 17590

You can't initialize fields (outside of methods) in different lines. Change your class to this:

namespace learningCsharp
{
    class Database
    {
        // We use these three SQLite objects:
        SQLiteConnection sqlite_conn;
        SQLiteCommand sqlite_cmd;
        SQLiteDataReader sqlite_datareader;

        //constructor called when initializing new instance
        public Database()
        {
            sqlite_conn = new SQLiteConnection("Data Source=database.db;Version=3;New=True;Compress=True;");
            sqlite_conn.Open();
            sqlite_cmd = sqlite_conn.CreateCommand();
        }
    }
}

Upvotes: 0

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