table database db sql

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

public class DBManager {

	private DBHelper helper = null;
	public static SQLiteDatabase db = null;
	private static DBManager dbManager = null;

	public DBManager(Context context) {
		try {
			helper = new DBHelper(context);
			if (db == null)
				db = helper.getWritableDatabase();

		} catch (Exception e) {
			return;
		}
	}

	public static SQLiteDatabase getDB() {
		return db;
	}

	public static DBManager getDBManager(Context context) {
		if (dbManager == null)
			dbManager = new DBManager(context);

		return dbManager;
	}

	public void insert(String table, ContentValues cv) {
		try {
			if (db.isOpen())
				db.insert(table, null, cv);
			else {
				db = helper.getWritableDatabase();
				db.insert(table, null, cv);
			}
		} catch (Exception e) {
			return;
		}
	}

	public void delete(String sql) {
		try {
			if (db.isOpen())
				db.execSQL(sql);
			else {
				db = helper.getWritableDatabase();
				db.execSQL(sql);
			}
		} catch (Exception e) {
			return;
		}
	}

	public Cursor query(String sql) {
		try {
			if (db.isOpen()) {
				Cursor cursor = db.rawQuery(sql, null);

				return cursor;
			} else {
				db = helper.getWritableDatabase();
				Cursor cursor = db.rawQuery(sql, null);

				return cursor;
			}
		} catch (Exception e) {

			return null;
		}
	}

	public boolean update(String table, ContentValues cv, String where, String[] arr) {
		try {
			if (db.isOpen())
				db.update(table, cv, where, arr);
			else {
				db = helper.getWritableDatabase();
				db.update(table, cv, where, arr);
			}

			return true;
		} catch (Exception e) {

			return false;
		}
	}

	public void closdDB() {
		try {
			if (db != null) {
				if (db.isOpen()) {
					db.close();
				}
			}
		} catch (Exception e) {
			return;
		}
	}
}

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHelper extends SQLiteOpenHelper{
	private static final String DB_NAME = "mydb.db";
	public static final String CHAT_TABLE = "mytable";
	private static final int VERSION = 1; 
	
	private static final String TABLE_CREATE = "create table if not exists " + CHAT_TABLE +
                                               "(" + 
                                               "id integer primary key autoincrement," +
                                               "content text," +
                                               "name text)";
	
	public DBHelper(Context context){
		super(context, DB_NAME, null, VERSION);
	}

	@Override
	public void onCreate(SQLiteDatabase db){
		try{
			db.execSQL(TABLE_CREATE);
		}catch(Exception e){
			return;
		}
	}

	@Override
	public void onUpgrade(SQLiteDatabase db, int arg1, int arg2){

	}
}

ContentValues cv = new ContentValues();
cv.put("content","value1");
cv.put("name","jack");
DBManager.getDBManager(MainActivity.this).insert(DBHelper.CHAT_TABLE, cv);