SQLite之C#版 System.Data.SQLite使用方法

SQLite简介

SQLite，是一款轻型的关系型数据库。它的设计目标是嵌入式。

它能够支持Windows/Linux/Unix等等主流的操作系统，同时能够跟很多程序语言相结合，比如 C++、C#、Object-C、PHP、Java等。

我是做手游开发的，在手机上使用SQLite 存储数据是很方便的。

System.Data.SqLite实践前期准备

1. System.Data.SQLite 库下载，用于C#操作SQLite的dll文件。下载地址：http://system.data.sqlite.org/index.html/doc/trunk/www/downloads.wiki
2. SQLite可视化工具下载，用于查看SQLite库数据表数据。下载地址：http://www.sqliteexpert.com/download.html

Tips:

1.根据自己的电脑是64bit或者32bit 以及使用的.NET Freamwork版本下载相应的的System.Data.SQLite。    下载解压文件如：

安装在指定目录后生成多个dll文件：

本文测试用的只有 System.Data.SQLite.dll 。对于SQLite库数据的增删改查已经足够用了。

2.SQLite数据库文件以.db为后缀。安装SQLite可视化工具后如图：

mydb是我测试用的数据库。

实践

对SQLite的增、删、改、查。

测试环境：VS2015 语言：C#

创建控制台新工程，引入System.Data.SQLite.dll 文件。

1.编写SQLite 操作类， 对SQLite数据操作进行封装为 SqLiteHelper，代码如下：

/// <summary>
  /// SQLite 操作类
  /// </summary>
  class SqLiteHelper
  {

    /// <summary>
    /// 数据库连接定义
    /// </summary>
    private SQLiteConnection dbConnection;

    /// <summary>
    /// SQL命令定义
    /// </summary>
    private SQLiteCommand dbCommand;

    /// <summary>
    /// 数据读取定义
    /// </summary>
    private SQLiteDataReader dataReader;

    /// <summary>
    /// 构造函数
    /// </summary>
    /// <param name="connectionString">连接SQLite库字符串</param>
    public SqLiteHelper(string connectionString)
    {
      try
      {
        dbConnection = new SQLiteConnection(connectionString);
        dbConnection.Open();
      }catch(Exception e)
      {
        Log(e.ToString());
      }
    }
    /// <summary>
    /// 执行SQL命令
    /// </summary>
    /// <returns>The query.</returns>
    /// <param name="queryString">SQL命令字符串</param>
    public SQLiteDataReader ExecuteQuery(string queryString)
    {
      try
      {
        dbCommand = dbConnection.CreateCommand();
        dbCommand.CommandText = queryString;
        dataReader = dbCommand.ExecuteReader();
      }catch(Exception e)
      {
        Log(e.Message);
      }

      return dataReader;
    }
    /// <summary>
    /// 关闭数据库连接
    /// </summary>
    public void CloseConnection()
    {
      //销毁Commend
      if(dbCommand !=null)
      {
        dbCommand.Cancel();
      }
      dbCommand = null;
      //销毁Reader
      if(dataReader != null)
      {
        dataReader.Close();
      }
      dataReader = null;
      //销毁Connection
      if(dbConnection != null)
      {
        dbConnection.Close();
      }
      dbConnection = null;

    }

    /// <summary>
    /// 读取整张数据表
    /// </summary>
    /// <returns>The full table.</returns>
    /// <param name="tableName">数据表名称</param>
    public SQLiteDataReader ReadFullTable(string tableName)
    {
      string queryString = "SELECT * FROM " + tableName;
      return ExecuteQuery(queryString);
    }

    /// <summary>
    /// 向指定数据表中插入数据
    /// </summary>
    /// <returns>The values.</returns>
    /// <param name="tableName">数据表名称</param>
    /// <param name="values">插入的数值</param>
    public SQLiteDataReader InsertValues(string tableName, string[] values)
    {
      //获取数据表中字段数目
      int fieldCount = ReadFullTable(tableName).FieldCount;
      //当插入的数据长度不等于字段数目时引发异常
      if (values.Length != fieldCount)
      {
        throw new SQLiteException("values.Length!=fieldCount");
      }

      string queryString = "INSERT INTO " + tableName + " VALUES (" + "'"+ values[0]+"'";
      for (int i = 1; i < values.Length; i++)
      {
        queryString += ", " + "'"+values[i] + "'";
      }
      queryString += " )";
      return ExecuteQuery(queryString);
    }

    /// <summary>
    /// 更新指定数据表内的数据
    /// </summary>
    /// <returns>The values.</returns>
    /// <param name="tableName">数据表名称</param>
    /// <param name="colNames">字段名</param>
    /// <param name="colValues">字段名对应的数据</param>
    /// <param name="key">关键字</param>
    /// <param name="value">关键字对应的值</param>
    /// <param name="operation">运算符：=,<,>,...，默认“=”</param>
    public SQLiteDataReader UpdateValues(string tableName, string[] colNames, string[] colValues, string key, string value, string operation="=")
    {
      //当字段名称和字段数值不对应时引发异常
      if (colNames.Length != colValues.Length)
      {
        throw new SQLiteException("colNames.Length!=colValues.Length");
      }

      string queryString = "UPDATE " + tableName + " SET " + colNames[0] + "=" + "'" + colValues[0] + "'";
      for (int i = 1; i < colValues.Length; i++)
      {
        queryString += ", " + colNames[i] + "=" + "'" + colValues[i] + "'";
      }
      queryString += " WHERE " + key + operation + "'" + value + "'";
      return ExecuteQuery(queryString);
    }

    /// <summary>
    /// 删除指定数据表内的数据
    /// </summary>
    /// <returns>The values.</returns>
    /// <param name="tableName">数据表名称</param>
    /// <param name="colNames">字段名</param>
    /// <param name="colValues">字段名对应的数据</param>
    public SQLiteDataReader DeleteValuesOR(string tableName, string[] colNames, string[] colValues, string[] operations)
    {
      //当字段名称和字段数值不对应时引发异常
      if (colNames.Length != colValues.Length || operations.Length != colNames.Length || operations.Length != colValues.Length)
      {
        throw new SQLiteException("colNames.Length!=colValues.Length || operations.Length!=colNames.Length || operations.Length!=colValues.Length");
      }

      string queryString = "DELETE FROM " + tableName + " WHERE " + colNames[0] + operations[0] + "'" + colValues[0] + "'";
      for (int i = 1; i < colValues.Length; i++)
      {
        queryString += "OR " + colNames[i] + operations[0] + "'" + colValues[i] + "'";
      }
      return ExecuteQuery(queryString);
    }

    /// <summary>
    /// 删除指定数据表内的数据
    /// </summary>
    /// <returns>The values.</returns>
    /// <param name="tableName">数据表名称</param>
    /// <param name="colNames">字段名</param>
    /// <param name="colValues">字段名对应的数据</param>
    public SQLiteDataReader DeleteValuesAND(string tableName, string[] colNames, string[] colValues, string[] operations)
    {
      //当字段名称和字段数值不对应时引发异常
      if (colNames.Length != colValues.Length || operations.Length != colNames.Length || operations.Length != colValues.Length)
      {
        throw new SQLiteException("colNames.Length!=colValues.Length || operations.Length!=colNames.Length || operations.Length!=colValues.Length");
      }

      string queryString = "DELETE FROM " + tableName + " WHERE " + colNames[0] + operations[0] + "'" + colValues[0] + "'";
      for (int i = 1; i < colValues.Length; i++)
      {
        queryString += " AND " + colNames[i] + operations[i] + "'" + colValues[i] + "'";
      }
      return ExecuteQuery(queryString);
    }

    /// <summary>
    /// 创建数据表
    /// </summary> +
    /// <returns>The table.</returns>
    /// <param name="tableName">数据表名</param>
    /// <param name="colNames">字段名</param>
    /// <param name="colTypes">字段名类型</param>
    public SQLiteDataReader CreateTable(string tableName, string[] colNames, string[] colTypes)
    {
      string queryString = "CREATE TABLE IF NOT EXISTS " + tableName + "( " + colNames[0] + " " + colTypes[0];
      for (int i = 1; i < colNames.Length; i++)
      {
        queryString += ", " + colNames[i] + " " + colTypes[i];
      }
      queryString += " ) ";
      return ExecuteQuery(queryString);
    }

    /// <summary>
    /// Reads the table.
    /// </summary>
    /// <returns>The table.</returns>
    /// <param name="tableName">Table name.</param>
    /// <param name="items">Items.</param>
    /// <param name="colNames">Col names.</param>
    /// <param name="operations">Operations.</param>
    /// <param name="colValues">Col values.</param>
    public SQLiteDataReader ReadTable(string tableName, string[] items, string[] colNames, string[] operations, string[] colValues)
    {
      string queryString = "SELECT " + items[0];
      for (int i = 1; i < items.Length; i++)
      {
        queryString += ", " + items[i];
      }
      queryString += " FROM " + tableName + " WHERE " + colNames[0] + " " + operations[0] + " " + colValues[0];
      for (int i = 0; i < colNames.Length; i++)
      {
        queryString += " AND " + colNames[i] + " " + operations[i] + " " + colValues[0] + " ";
      }
      return ExecuteQuery(queryString);
    }

    /// <summary>
    /// 本类log
    /// </summary>
    /// <param name="s"></param>
    static void Log(string s)
    {
      Console.WriteLine("class SqLiteHelper:::" + s);
    }
  }

Tips:1.别忘了引入：using System.Data.SQLite;

2.引入System.Data.SQLite.dll的同时，需要将 System.Data.SQLite.dll.config 文件放在同级目录下。否则加载dll文件时报错。

2.在工程主函数Main里面添加测试代码

class Program
  {
    private static SqLiteHelper sql;
    static void Main(string[] args)
    {
      sql = new SqLiteHelper("data source=mydb.db");

      //创建名为table1的数据表
      sql.CreateTable("table1", new string[] { "ID", "Name", "Age", "Email" }, new string[] { "INTEGER", "TEXT", "INTEGER", "TEXT" });
      //插入两条数据
      sql.InsertValues("table1",new string[]{"1","张三","22","Zhang@163.com" });
      sql.InsertValues("table1", new string[] { "2", "李四", "25", "Li4@163.com" });

      //更新数据，将Name="张三"的记录中的Name改为"Zhang3"
      sql.UpdateValues("table1", new string[] { "Name" }, new string[] { "ZhangSan" }, "Name", "Zhang3");

      //删除Name="张三"且Age=26的记录,DeleteValuesOR方法类似
      sql.DeleteValuesAND("table1", new string[] { "Name", "Age" }, new string[] { "张三", "22" }, new string[] { "=", "=" });

      //读取整张表
      SQLiteDataReader reader = sql.ReadFullTable("table1");
      while (reader.Read())
      {
        //读取ID
        Log(""+reader.GetInt32(reader.GetOrdinal("ID")));
        //读取Name
        Log(""+reader.GetString(reader.GetOrdinal("Name")));
        //读取Age
        Log(""+reader.GetInt32(reader.GetOrdinal("Age")));
        //读取Email
        Log(reader.GetString(reader.GetOrdinal("Email")));
      }

      while (true)
      {
        Console.ReadLine();
      }
    }

    static void Log(string s)
    {
      Console.WriteLine(""+s);
    }
  }

Tips:1.别忘了引入：using System.Data.SQLite;

vs2015有NuGet，vs2013默认没有这个插件。

System.Data.SQLite 可以在VS中直接通过NuGet获取到。

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