SQLite 之 C#版 System.Data.SQLite 使用

簡介

SQLite簡介

    SQLite，是一款輕型的關係型數據庫。它的設計目標是嵌入式。

    它可以支持Windows/Linux/Unix等等主流的操做系統，同時可以跟不少程序語言相結合，好比 C++、C#、Object-C、PHP、Java等。

    我是作手遊開發的，在手機上使用SQLite 存儲數據是很方便的。 

System.Data.SqLite實踐前期準備

1. System.Data.SQLite 庫下載，用於C#操做SQLite的dll文件。下載地址：http://system.data.sqlite.org/index.html/doc/trunk/www/downloads.wiki
2. SQLite可視化工具下載，用於查看SQLite庫數據表數據。下載地址：http://www.sqliteexpert.com/download.html

Tips:

    1.根據本身的電腦是64bit或者32bit 以及使用的.NET Freamwork版本下載相應的的System.Data.SQLite。    下載解壓文件如：

 

     安裝在指定目錄後生成多個dll文件：

     本文測試用的只有 System.Data.SQLite.dll 。對於SQLite庫數據的增刪改查已經足夠用了。

 

    2.SQLite數據庫文件以.db爲後綴。安裝SQLite可視化工具後如圖：

     mydb是我測試用的數據庫。

實踐

    對SQLite的增、刪、改、查。

    測試環境：VS2015  語言：C#

 

    建立控制檯新工程，引入System.Data.SQLite.dll 文件。   

    1.編寫SQLite 操做類， 對SQLite數據操做進行封裝爲 SqLiteHelper，代碼以下：

    /// <summary>
    /// SQLite 操做類
    /// </summary>
    class SqLiteHelper
    {

        /// <summary>
        /// 數據庫鏈接定義
        /// </summary>
        private SQLiteConnection dbConnection;

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

        /// <summary>
        /// 數據讀取定義
        /// </summary>
        private SQLiteDataReader dataReader;

        /// <summary>
        /// 構造函數
        /// </summary>
        /// <param name="connectionString">鏈接SQLite庫字符串</param>
        public SqLiteHelper(string connectionString)
        {
            try
            {
                dbConnection = new SQLiteConnection(connectionString);
                dbConnection.Open();
            }catch(Exception e)
            {
                Log(e.ToString());
            }
        }
        /// <summary>
        /// 執行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>
        /// 關閉數據庫鏈接
        /// </summary>
        public void CloseConnection()
        {
            //銷燬Commend
            if(dbCommand !=null)
            {
                dbCommand.Cancel();
            }
            dbCommand = null;
            //銷燬Reader
            if(dataReader != null)
            {
                dataReader.Close();
            }
            dataReader = null;
            //銷燬Connection
            if(dbConnection != null)
            {
                dbConnection.Close();
            }
            dbConnection = null;

        }

        /// <summary>
        /// 讀取整張數據表
        /// </summary>
        /// <returns>The full table.</returns>
        /// <param name="tableName">數據表名稱</param>
        public SQLiteDataReader ReadFullTable(string tableName)
        {
            string queryString = "SELECT * FROM " + tableName;
            return ExecuteQuery(queryString);
        }


        /// <summary>
        /// 向指定數據表中插入數據
        /// </summary>
        /// <returns>The values.</returns>
        /// <param name="tableName">數據表名稱</param>
        /// <param name="values">插入的數值</param>
        public SQLiteDataReader InsertValues(string tableName, string[] values)
        {
            //獲取數據表中字段數目
            int fieldCount = ReadFullTable(tableName).FieldCount;
            //當插入的數據長度不等於字段數目時引起異常
            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>
        /// 更新指定數據表內的數據
        /// </summary>
        /// <returns>The values.</returns>
        /// <param name="tableName">數據表名稱</param>
        /// <param name="colNames">字段名</param>
        /// <param name="colValues">字段名對應的數據</param>
        /// <param name="key">關鍵字</param>
        /// <param name="value">關鍵字對應的值</param>
        /// <param name="operation">運算符：=,<,>,...，默認「=」</param>
        public SQLiteDataReader UpdateValues(string tableName, string[] colNames, string[] colValues, string key, string value, string operation="=")
        {
            //當字段名稱和字段數值不對應時引起異常
            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>
        /// 刪除指定數據表內的數據
        /// </summary>
        /// <returns>The values.</returns>
        /// <param name="tableName">數據表名稱</param>
        /// <param name="colNames">字段名</param>
        /// <param name="colValues">字段名對應的數據</param>
        public SQLiteDataReader DeleteValuesOR(string tableName, string[] colNames, string[] colValues, string[] operations)
        {
            //當字段名稱和字段數值不對應時引起異常
            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>
        /// 刪除指定數據表內的數據
        /// </summary>
        /// <returns>The values.</returns>
        /// <param name="tableName">數據表名稱</param>
        /// <param name="colNames">字段名</param>
        /// <param name="colValues">字段名對應的數據</param>
        public SQLiteDataReader DeleteValuesAND(string tableName, string[] colNames, string[] colValues, string[] operations)
        {
            //當字段名稱和字段數值不對應時引起異常
            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>
        /// 建立數據表
        /// </summary> +
        /// <returns>The table.</returns>
        /// <param name="tableName">數據表名</param>
        /// <param name="colNames">字段名</param>
        /// <param name="colTypes">字段名類型</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>
        /// 本類log
        /// </summary>
        /// <param name="s"></param>
        static void Log(string s)
        {
            Console.WriteLine("class SqLiteHelper:::" + s);
        }
    }

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

            2.引入System.Data.SQLite.dll的同時，須要將 System.Data.SQLite.dll.config 文件放在同級目錄下。不然加載dll文件時報錯。

 

    2.在工程主函數Main裏面添加測試代碼

class Program
    {
        private static SqLiteHelper sql;
        static void Main(string[] args)
        {
            sql = new SqLiteHelper("data source=mydb.db");
            
            
            //建立名爲table1的數據表
            sql.CreateTable("table1", new string[] { "ID", "Name", "Age", "Email" }, new string[] { "INTEGER", "TEXT", "INTEGER", "TEXT" });
            //插入兩條數據
            sql.InsertValues("table1",new string[]{"1","張三","22","Zhang@163.com" });
            sql.InsertValues("table1", new string[] { "2", "李四", "25", "Li4@163.com" });

            //更新數據，將Name="張三"的記錄中的Name改成"Zhang3"
            sql.UpdateValues("table1", new string[] { "Name" }, new string[] { "ZhangSan" }, "Name", "Zhang3");

            //刪除Name="張三"且Age=26的記錄,DeleteValuesOR方法相似
            sql.DeleteValuesAND("table1", new string[] { "Name", "Age" }, new string[] { "張三", "22" }, new string[] { "=", "=" });


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

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

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

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

 

 

    歡迎討論！