Sqlite笔记2--Sqlite在C#中的应用

Sqlite Helper类:

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SQLite;
using System.Windows.Forms;

class SQLiteDatabase
{
	String dbConnection;

	/// 

	///     Default Constructor for SQLiteDatabase Class.
	/// 
	public SQLiteDatabase()
	{
		dbConnection = "Data Source=recipes.s3db";
	}

	/// 

	///     Single Param Constructor for specifying the DB file.
	/// 
	/// The File containing the DB
	public SQLiteDatabase(String inputFile)
	{
		dbConnection = String.Format("Data Source={0}", inputFile);
	}

	/// 

	///     Single Param Constructor for specifying advanced connection options.
	/// 
	/// A dictionary containing all desired options and their values
	public SQLiteDatabase(Dictionary connectionOpts)
	{
		String str = "";
		foreach (KeyValuePair row in connectionOpts)
		{
			str += String.Format("{0}={1}; ", row.Key, row.Value);
		}
		str = str.Trim().Substring(0, str.Length - 1);
		dbConnection = str;
	}

	/// 

	///     Allows the programmer to run a query against the Database.
	/// 
	/// The SQL to run
	/// A DataTable containing the result set.
	public DataTable GetDataTable(string sql)
	{
		DataTable dt = new DataTable();
		try
		{
			SQLiteConnection cnn = new SQLiteConnection(dbConnection);
			cnn.Open();
			SQLiteCommand mycommand = new SQLiteCommand(cnn);
			mycommand.CommandText = sql;
			SQLiteDataReader reader = mycommand.ExecuteReader();
			dt.Load(reader);
			reader.Close();
			cnn.Close();
		}
		catch (Exception e)
		{
			throw new Exception(e.Message);
		}
		return dt;
	}
	
	/// 

	///     Allows the programmer to interact with the database for purposes other than a query.
	/// 
	/// The SQL to be run.
	/// An Integer containing the number of rows updated.
	public int ExecuteNonQuery(string sql)
	{
		SQLiteConnection cnn = new SQLiteConnection(dbConnection);
		cnn.Open();
		SQLiteCommand mycommand = new SQLiteCommand(cnn);
		mycommand.CommandText = sql;
		int rowsUpdated = mycommand.ExecuteNonQuery();
		cnn.Close();
		return rowsUpdated;
	}

	/// 

	///     Allows the programmer to retrieve single items from the DB.
	/// 
	/// The query to run.
	/// A string.
	public string ExecuteScalar(string sql)
	{
		SQLiteConnection cnn = new SQLiteConnection(dbConnection);
		cnn.Open();
		SQLiteCommand mycommand = new SQLiteCommand(cnn);
		mycommand.CommandText = sql;
		object value = mycommand.ExecuteScalar();
		cnn.Close();
		if (value != null)
		{
			return value.ToString();
		}
		return "";
	}

	/// 

	///     Allows the programmer to easily update rows in the DB.
	/// 
	/// The table to update.
	/// A dictionary containing Column names and their new values.
	/// The where clause for the update statement.
	/// A boolean true or false to signify success or failure.
	public bool Update(String tableName, Dictionary data, String where)
	{
		String vals = "";
		Boolean returnCode = true;
		if (data.Count >= 1)
		{
			foreach (KeyValuePair val in data)
			{
				vals += String.Format(" {0} = '{1}',", val.Key.ToString(), val.Value.ToString());
			}
			vals = vals.Substring(0, vals.Length - 1);
		}
		try
		{
			this.ExecuteNonQuery(String.Format("update {0} set {1} where {2};", tableName, vals, where));
		}
		catch
		{
			returnCode = false;
		}
		return returnCode;
	}

	/// 

	///     Allows the programmer to easily delete rows from the DB.
	/// 
	/// The table from which to delete.
	/// The where clause for the delete.
	/// A boolean true or false to signify success or failure.
	public bool Delete(String tableName, String where)
	{
		Boolean returnCode = true;
		try
		{
			this.ExecuteNonQuery(String.Format("delete from {0} where {1};", tableName, where));
		}
		catch (Exception fail)
		{
			MessageBox.Show(fail.Message);
			returnCode = false;
		}
		return returnCode;
	}

	/// 

	///     Allows the programmer to easily insert into the DB
	/// 
	/// The table into which we insert the data.
	/// A dictionary containing the column names and data for the insert.
	/// A boolean true or false to signify success or failure.
	public bool Insert(String tableName, Dictionary data)
	{
		String columns = "";
		String values = "";
		Boolean returnCode = true;
		foreach (KeyValuePair val in data)
		{
			columns += String.Format(" {0},", val.Key.ToString());
			values += String.Format(" '{0}',", val.Value);
		}
		columns = columns.Substring(0, columns.Length - 1);
		values = values.Substring(0, values.Length - 1);
		try
		{
			this.ExecuteNonQuery(String.Format("insert into {0}({1}) values({2});", tableName, columns, values));
		}
		catch(Exception fail)
		{
			MessageBox.Show(fail.Message);
			returnCode = false;
		}
		return returnCode;
	}

	/// 

	///     Allows the programmer to easily delete all data from the DB.
	/// 
	/// A boolean true or false to signify success or failure.
	public bool ClearDB()
	{
		DataTable tables;
		try
		{
			tables = this.GetDataTable("select NAME from SQLITE_MASTER where type='table' order by NAME;");
			foreach (DataRow table in tables.Rows)
			{
				this.ClearTable(table["NAME"].ToString());
			}
			return true;
		}
		catch
		{
			return false;
		}
	}

	/// 

	///     Allows the user to easily clear all data from a specific table.
	/// 
	/// The name of the table to clear.
	/// A boolean true or false to signify success or failure.
	public bool ClearTable(String table)
	{
		try
		{
			
			this.ExecuteNonQuery(String.Format("delete from {0};", table));
			return true;
		}
		catch
		{
			return false;
		}
	}       
}