C#中增加SQLite事务操作支持与使用方法

本文实例讲述了C#中增加SQLite事务操作支持与使用方法。分享给大家供大家参考，具体如下：

在C#中使用Sqlite增加对transaction支持

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SQLite;
using System.Globalization;
using System.Linq;
using System.Windows.Forms;
namespace Simple_Disk_Catalog
{
  public class SQLiteDatabase
  {
    String DBConnection;
    private readonly SQLiteTransaction _sqLiteTransaction;
    private readonly SQLiteConnection _sqLiteConnection;
    private readonly bool _transaction;
    /// <summary>
    ///   Default Constructor for SQLiteDatabase Class.
    /// </summary>
    /// <param name="transaction">Allow programmers to insert, update and delete values in one transaction</param>
    public SQLiteDatabase(bool transaction = false)
    {
      _transaction = transaction;
      DBConnection = "Data Source=recipes.s3db";
      if (transaction)
      {
        _sqLiteConnection = new SQLiteConnection(DBConnection);
        _sqLiteConnection.Open();
        _sqLiteTransaction = _sqLiteConnection.BeginTransaction();
      }
    }
    /// <summary>
    ///   Single Param Constructor for specifying the DB file.
    /// </summary>
    /// <param name="inputFile">The File containing the DB</param>
    public SQLiteDatabase(String inputFile)
    {
      DBConnection = String.Format("Data Source={0}", inputFile);
    }
    /// <summary>
    ///   Commit transaction to the database.
    /// </summary>
    public void CommitTransaction()
    {
      _sqLiteTransaction.Commit();
      _sqLiteTransaction.Dispose();
      _sqLiteConnection.Close();
      _sqLiteConnection.Dispose();
    }
    /// <summary>
    ///   Single Param Constructor for specifying advanced connection options.
    /// </summary>
    /// <param name="connectionOpts">A dictionary containing all desired options and their values</param>
    public SQLiteDatabase(Dictionary<String, String> connectionOpts)
    {
      String str = connectionOpts.Aggregate("", (current, row) => current + String.Format("{0}={1}; ", row.Key, row.Value));
      str = str.Trim().Substring(0, str.Length - 1);
      DBConnection = str;
    }
    /// <summary>
    ///   Allows the programmer to create new database file.
    /// </summary>
    /// <param name="filePath">Full path of a new database file.</param>
    /// <returns>true or false to represent success or failure.</returns>
    public static bool CreateDB(string filePath)
    {
      try
      {
        SQLiteConnection.CreateFile(filePath);
        return true;
      }
      catch (Exception e)
      {
        MessageBox.Show(e.Message, e.GetType().ToString(), MessageBoxButtons.OK, MessageBoxIcon.Error);
        return false;
      }
    }
    /// <summary>
    ///   Allows the programmer to run a query against the Database.
    /// </summary>
    /// <param name="sql">The SQL to run</param>
    /// <param name="allowDBNullColumns">Allow null value for columns in this collection.</param>
    /// <returns>A DataTable containing the result set.</returns>
    public DataTable GetDataTable(string sql, IEnumerable<string> allowDBNullColumns = null)
    {
      var dt = new DataTable();
      if (allowDBNullColumns != null)
        foreach (var s in allowDBNullColumns)
        {
          dt.Columns.Add(s);
          dt.Columns[s].AllowDBNull = true;
        }
      try
      {
        var cnn = new SQLiteConnection(DBConnection);
        cnn.Open();
        var mycommand = new SQLiteCommand(cnn) {CommandText = sql};
        var reader = mycommand.ExecuteReader();
        dt.Load(reader);
        reader.Close();
        cnn.Close();
      }
      catch (Exception e)
      {
        throw new Exception(e.Message);
      }
      return dt;
    }
    public string RetrieveOriginal(string value)
    {
      return
        value.Replace("&", "&").Replace("<", "<").Replace(">", "<").Replace(""", "\"").Replace(
          "'", "'");
    }
    /// <summary>
    ///   Allows the programmer to interact with the database for purposes other than a query.
    /// </summary>
    /// <param name="sql">The SQL to be run.</param>
    /// <returns>An Integer containing the number of rows updated.</returns>
    public int ExecuteNonQuery(string sql)
    {
      if (!_transaction)
      {
        var cnn = new SQLiteConnection(DBConnection);
        cnn.Open();
        var mycommand = new SQLiteCommand(cnn) {CommandText = sql};
        var rowsUpdated = mycommand.ExecuteNonQuery();
        cnn.Close();
        return rowsUpdated;
      }
      else
      {
        var mycommand = new SQLiteCommand(_sqLiteConnection) { CommandText = sql };
        return mycommand.ExecuteNonQuery();
      }
    }
    /// <summary>
    ///   Allows the programmer to retrieve single items from the DB.
    /// </summary>
    /// <param name="sql">The query to run.</param>
    /// <returns>A string.</returns>
    public string ExecuteScalar(string sql)
    {
      if (!_transaction)
      {
        var cnn = new SQLiteConnection(DBConnection);
        cnn.Open();
        var mycommand = new SQLiteCommand(cnn) {CommandText = sql};
        var value = mycommand.ExecuteScalar();
        cnn.Close();
        return value != null ? value.ToString() : "";
      }
      else
      {
        var sqLiteCommand = new SQLiteCommand(_sqLiteConnection) { CommandText = sql };
        var value = sqLiteCommand.ExecuteScalar();
        return value != null ? value.ToString() : "";
      }
    }
    /// <summary>
    ///   Allows the programmer to easily update rows in the DB.
    /// </summary>
    /// <param name="tableName">The table to update.</param>
    /// <param name="data">A dictionary containing Column names and their new values.</param>
    /// <param name="where">The where clause for the update statement.</param>
    /// <returns>A boolean true or false to signify success or failure.</returns>
    public bool Update(String tableName, Dictionary<String, String> data, String where)
    {
      String vals = "";
      Boolean returnCode = true;
      if (data.Count >= 1)
      {
        vals = data.Aggregate(vals, (current, val) => current + String.Format(" {0} = '{1}',", val.Key.ToString(CultureInfo.InvariantCulture), val.Value.ToString(CultureInfo.InvariantCulture)));
        vals = vals.Substring(0, vals.Length - 1);
      }
      try
      {
        ExecuteNonQuery(String.Format("update {0} set {1} where {2};", tableName, vals, where));
      }
      catch
      {
        returnCode = false;
      }
      return returnCode;
    }
    /// <summary>
    ///   Allows the programmer to easily delete rows from the DB.
    /// </summary>
    /// <param name="tableName">The table from which to delete.</param>
    /// <param name="where">The where clause for the delete.</param>
    /// <returns>A boolean true or false to signify success or failure.</returns>
    public bool Delete(String tableName, String where)
    {
      Boolean returnCode = true;
      try
      {
        ExecuteNonQuery(String.Format("delete from {0} where {1};", tableName, where));
      }
      catch (Exception fail)
      {
        MessageBox.Show(fail.Message, fail.GetType().ToString(), MessageBoxButtons.OK, MessageBoxIcon.Error);
        returnCode = false;
      }
      return returnCode;
    }
    /// <summary>
    ///   Allows the programmer to easily insert into the DB
    /// </summary>
    /// <param name="tableName">The table into which we insert the data.</param>
    /// <param name="data">A dictionary containing the column names and data for the insert.</param>
    /// <returns>returns last inserted row id if it's value is zero than it means failure.</returns>
    public long Insert(String tableName, Dictionary<String, String> data)
    {
      String columns = "";
      String values = "";
      String value;
      foreach (KeyValuePair<String, String> val in data)
      {
        columns += String.Format(" {0},", val.Key.ToString(CultureInfo.InvariantCulture));
        values += String.Format(" '{0}',", val.Value);
      }
      columns = columns.Substring(0, columns.Length - 1);
      values = values.Substring(0, values.Length - 1);
      try
      {
        if (!_transaction)
        {
          var cnn = new SQLiteConnection(DBConnection);
          cnn.Open();
          var sqLiteCommand = new SQLiteCommand(cnn)
                    {
                      CommandText =
                        String.Format("insert into {0}({1}) values({2});", tableName, columns,
                               values)
                    };
          sqLiteCommand.ExecuteNonQuery();
          sqLiteCommand = new SQLiteCommand(cnn) { CommandText = "SELECT last_insert_rowid()" };
          value = sqLiteCommand.ExecuteScalar().ToString();
        }
        else
        {
          ExecuteNonQuery(String.Format("insert into {0}({1}) values({2});", tableName, columns, values));
          value = ExecuteScalar("SELECT last_insert_rowid()");
        }
      }
      catch (Exception fail)
      {
        MessageBox.Show(fail.Message, fail.GetType().ToString(), MessageBoxButtons.OK, MessageBoxIcon.Error);
        return 0;
      }
      return long.Parse(value);
    }
    /// <summary>
    ///   Allows the programmer to easily delete all data from the DB.
    /// </summary>
    /// <returns>A boolean true or false to signify success or failure.</returns>
    public bool ClearDB()
    {
      try
      {
        var tables = GetDataTable("select NAME from SQLITE_MASTER where type='table' order by NAME;");
        foreach (DataRow table in tables.Rows)
        {
          ClearTable(table["NAME"].ToString());
        }
        return true;
      }
      catch
      {
        return false;
      }
    }
    /// <summary>
    ///   Allows the user to easily clear all data from a specific table.
    /// </summary>
    /// <param name="table">The name of the table to clear.</param>
    /// <returns>A boolean true or false to signify success or failure.</returns>
    public bool ClearTable(String table)
    {
      try
      {
        ExecuteNonQuery(String.Format("delete from {0};", table));
        return true;
      }
      catch
      {
        return false;
      }
    }
    /// <summary>
    ///   Allows the user to easily reduce size of database.
    /// </summary>
    /// <returns>A boolean true or false to signify success or failure.</returns>
    public bool CompactDB()
    {
      try
      {
        ExecuteNonQuery("Vacuum;");
        return true;
      }
      catch (Exception)
      {
        return false;
      }
    }
  }
}

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