C# SQLite 数据库

数据库

Oracle。Oracle的应用，主要在传统行业的数据化业务中，比如：银行、金融这样的对可用性、健壮性、安全性、实时性要求极高的业务

MS SQL Server。windows生态系统的产品，好处坏处都很分明。好处就是，高度集成化，微软也提供了整套的软件方案，基本上一套win系统装下来就齐活了。因此，不那么缺钱，但很缺IT人才的中小企业，会偏爱 MS SQL Server 。例如，自建ERP系统、商业智能、垂直领域零售商、餐饮、事业单位等等。

MySQL。MySQL基本是生于互联网，长于互联网。其应用实例也大都集中于互联网方向

SQLite介绍

SQLite，是一款轻型的数据库，是遵守ACID的关系型数据库管理系统，它包含在一个相对小的C库中。它的设计目标是嵌入式的，而且目前已经在很多嵌入式产品中使用了它，它占用资源非常的低，在嵌入式设备中，可能只需要几百K的内存就够了。

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#、PHP、Java等，还有ODBC接口。SQLite第一个Alpha版本诞生于2000年5月。 至2015年已经有15个年头。

Windows平台使用

1、在Assets目录下创建Plugins目录，将Mono.Data.Sqlite.dll、System.Data.dll、sqlite3.dll三个文件放到工程Plugins目录下。

2、在Assets目录下创建StreamingAssets目录，把db放在该目录内。

3、将DbAccess.cs脚本添加到工程中

Android平台使用

1、在Assets目录下创建Plugins目录，将Mono.Data.Sqlite.dll、System.Data.dll、sqlite3.dll三个文件放到工程Plugins目录下。

2、然后在Plugins目录下建立Android目录，再将libsqlite3.so放到Android目录下。

3、在Assets目录下创建StreamingAssets目录，把db放在该目录内。 4、将DbAccess.cs脚本添加到工程中。

SQLite的数据库常规操作封装的通用类

 using UnityEngine;
 using System;
 using System.Collections;
 using Mono.Data.Sqlite;
 /// <summary>
 /// SQLite数据库操作类
 /// </summary>
 public class DbAccess
 {
     private SqliteConnection conn; // SQLite连接
     private SqliteCommand cmd; // SQLite命令
     private SqliteDataReader reader;
     public DbAccess (string connectionString)
     {
         OpenDB (connectionString);
     }
     public DbAccess (){ }
     /// <summary>
     /// 打开数据库
     /// </summary>
     /// <param name="connectionString"></param>
     public void OpenDB (string connectionString)
     {
         try
         {
             conn = new SqliteConnection (connectionString);
             conn.Open ();
             Debug.Log ("Connected to db,连接数据库成功！");
         }
         catch(Exception e)
         {
             string temp1 = e.ToString();
             Debug.Log(temp1);
         }
     }
     /// <summary>
     /// 关闭数据库连接
     /// </summary>
     public void CloseSqlConnection ()
     {
         if (cmd != null) { cmd.Dispose (); cmd = null; }
         if (reader != null) { reader.Dispose (); reader = null;}
         if (conn != null) {    conn.Close (); conn = null;}
         Debug.Log ("Disconnected from db.关闭数据库！");
     }
     /// <summary>
     /// 执行SQL语句
     /// </summary>
     /// <param name="sqlQuery"></param>
     /// <returns></returns>
     public SqliteDataReader ExecuteQuery ( string sqlQuery )
     {
         Debug.Log( "ExecuteQuery:: " + sqlQuery );
         cmd = conn.CreateCommand ();
         cmd.CommandText = sqlQuery;
         reader = cmd.ExecuteReader ();
         return reader;
     }

     /// <summary>
     /// 查询表中全部数据 param tableName=表名
     /// </summary>
     public SqliteDataReader ReadFullTable (string tableName)
     {
         string query = "SELECT * FROM " + tableName;
         return ExecuteQuery (query);
     }
     /// <summary>
     /// 插入数据 param tableName=表名 values=插入数据内容
     /// </summary>
     public SqliteDataReader InsertInto (string tableName, string[] values)
     {
         string query = "INSERT INTO " + tableName + " VALUES (" + values[];
         for (int i = ; i < values.Length; ++i) {
             query += ", " + values[i];
         }
         query += ")";
         return ExecuteQuery (query);
     }
     /// <summary>
     /// 更新数据 param tableName=表名 cols=更新字段 colsvalues=更新内容 selectkey=查找字段（主键) selectvalue=查找内容
     /// </summary>
     public SqliteDataReader UpdateInto (string tableName, string []cols,string []colsvalues,string selectkey,string selectvalue)
     {
         string query = "UPDATE "+tableName+" SET "+cols[]+" = "+colsvalues[];
         for (int i = ; i < colsvalues.Length; ++i) {
             query += ", " +cols[i]+" ="+ colsvalues[i];
         }
         query += " WHERE "+selectkey+" = "+selectvalue+" ";
         return ExecuteQuery (query);
     }

     /// <summary>
     /// 删除数据 param tableName=表名 cols=字段 colsvalues=内容
     /// </summary>
     public SqliteDataReader Delete(string tableName,string []cols,string []colsvalues)
     {
         string query = "DELETE FROM "+tableName + " WHERE " +cols[] +" = " + colsvalues[];
         for (int i = ; i < colsvalues.Length; ++i) {
             query += " or " +cols[i]+" = "+ colsvalues[i];
         }
         return ExecuteQuery (query);
     }
     /// <summary>
     /// 插入数据 param tableName=表名 cols=插入字段 value=插入内容
     /// </summary>
     public SqliteDataReader InsertIntoSpecific (string tableName, string[] cols, string[] values)
     {
         if (cols.Length != values.Length) {
             throw new SqliteException ("columns.Length != values.Length");
         }
         string query = "INSERT INTO " + tableName + "(" + cols[];
         for (int i = ; i < cols.Length; ++i) {
             query += ", " + cols[i];
         }
         query += ") VALUES (" + values[];
         for (int i = ; i < values.Length; ++i) {
             query += ", " + values[i];
         }
         query += ")";
         return ExecuteQuery (query);
     }
     /// <summary>
     /// 删除表中全部数据
     /// </summary>
     public SqliteDataReader DeleteContents (string tableName)
     {
         string query = "DELETE FROM " + tableName;
         return ExecuteQuery (query);
     }
     /// <summary>
     /// 创建表 param name=表名 col=字段名 colType=字段类型
     /// </summary>
     public SqliteDataReader CreateTable (string name, string[] col, string[] colType)
     {
         if (col.Length != colType.Length) {
             throw new SqliteException ("columns.Length != colType.Length");
         }
         string query = "CREATE TABLE " + name + " (" + col[] + " " + colType[];
         for (int i = ; i < col.Length; ++i) {
             query += ", " + col[i] + " " + colType[i];
         }
         query += ")";
         return ExecuteQuery (query);
     }
     /// <summary>
     /// 按条件查询数据 param tableName=表名 items=查询字段 col=查找字段 operation=运算符 values=内容
     /// </summary>
     public SqliteDataReader SelectWhere (string tableName, string[] items, string[] col, string[] operation, string[] values)
     {
         if (col.Length != operation.Length || operation.Length != values.Length) {
             throw new SqliteException ("col.Length != operation.Length != values.Length");
         }
         string query = "SELECT " + items[];
         for (int i = ; i < items.Length; ++i) {
             query += ", " + items[i];
         }
         query += " FROM " + tableName + " WHERE " + col[] + operation[] + "'" + values[] + "' ";
         for (int i = ; i < col.Length; ++i) {
             query += " AND " + col[i] + operation[i] + "'" + values[i] + "' ";
         }
         return ExecuteQuery (query);
     }
     /// <summary>
     /// 查询表
     /// </summary>
     public SqliteDataReader Select(string tableName, string col, string values)
     {
         string query = "SELECT * FROM " + tableName  + " WHERE " + col + " = " + values;
         return ExecuteQuery (query);
     }
     public SqliteDataReader Select(string tableName, string col,string operation, string values)
     {
         string query = "SELECT * FROM " + tableName  + " WHERE " + col + operation + values;
         return ExecuteQuery (query);
     }
     /// <summary>
     /// 升序查询
     /// </summary>
     public SqliteDataReader SelectOrderASC (string tableName,string col)
     {
         string query = "SELECT * FROM " + tableName  + " ORDER BY " + col + " ASC";
         return ExecuteQuery (query);
     }
     /// <summary>
     /// 降序查询
     /// </summary>
     public SqliteDataReader SelectOrderDESC (string tableName,string col)
     {
         string query = "SELECT * FROM " + tableName  + " ORDER BY " + col + " DESC";
         return ExecuteQuery (query);
     }
     /// <summary>
     /// 查询表行数
     /// </summary>
     public SqliteDataReader SelectCount(string tableName)
     {
         string query = "SELECT COUNT(*) FROM " + tableName;
         return ExecuteQuery (query);
     }
 }

DbAccess

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using Mono .Data .Sqlite;

 namespace ns
 {
     /// <summary>
     ///  打开和关闭数据库
     /// </summary>
     public class SQLiteHelper : MonoBehaviour
     {
         protected string dbName = "test2.db"; // 文件名
         private string filePath // 文件路径
         {
             get { return Application .streamingAssetsPath + "/" + dbName; }
         }

         protected DbAccess db; // dbAccess实例
         protected SqliteDataReader reader;//
         /// <summary>
         /// 打开数据库
         /// </summary>
         protected void OpenDB()
         {
             db = new DbAccess( "URI=file:" + filePath );
         }
         /// <summary>
         /// 关闭数据库
         /// </summary>
         protected void CloseDB()
         {
             if( reader != null )
             {
                 reader .Close();
                 reader = null;
             }

             db .CloseSqlConnection();
         }
         /// <summary>
         /// 对象前后添加单引号
         /// </summary>
         /// <param name="o"></param>
         /// <returns></returns>
         protected string GetStr( object o )
         {
             return "'" + o + "'";
         }

     }
 }

SQLiteHelper

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using ns;

 public class MySQLiteDemo : MySQLiteHelper
 {
     /// <summary>
     /// 创建表
     /// </summary>
     private void CreateTable()
     {
         //打开数据库
         OpenDB();

         db.CreateTable("MyRole", new string[] { "id", "name", "age", "lv", "exp" },
             new string[] { "int", "text", "int", "int", "float" });
         //关闭数据库
         CloseDB();
     }

     /// <summary>
     /// 插入数据
     /// </summary>
     private void InsertData()
     {
         //打开数据库
         OpenDB();
         //插入数据库
         db.InsertInto
             ("MyRole", new string[] { GetStr(""), GetStr("张三"), GetStr(""), GetStr(""), GetStr("") });
         db.InsertInto
             ("MyRole", new string[] { GetStr(""), GetStr("李四"), GetStr(""), GetStr(""), GetStr("") });
         db.InsertInto
             ("MyRole", new string[] { GetStr(""), GetStr("王五"), GetStr(""), GetStr(""), GetStr("") });
         db.InsertInto
             ("MyRole", new string[] { GetStr(""), GetStr("赵六"), GetStr(""), GetStr(""), GetStr("") });

         //关闭数据库
         CloseDB();
     }

     /// <summary>
     /// 删除数据库
     /// </summary>
     private void DeleteData()
     {
         //打开数据库
         OpenDB();
         // 删除数据: 多个条件直接是或的关系
         // DELETE FROM Role WHERE id = 1 or lv = 13

         //db.Delete("MyRole",
         //    new string[] { "id", "lv" },
         //    new string[] { "1", "130" }
         //    );
         db.DeleteContents("MyRole");
         //关闭数据库

         CloseDB();
     }
     /// <summary>
     /// 更新数据
     /// </summary>
     private void UpdateData()
     {
         //打开数据库
         OpenDB();
         // 更新数据: id为1数据 exp改为350 lv改为16
         // UPDATE Role SET exp = 350, lv =16 WHERE id = 1
         db.UpdateInto("MyRole",
             new string[] { "exp", "lv" }, new string[] { "", "", }, "id", "");
         //关闭数据库
         CloseDB();
     }
     // 查找数据
     private void SearchData()
     {
         OpenDB();
         // 查询 查找id为3 lv为21的数据
         // 找到 name 和 age
         // 多个条件之间是与的关系
         // SELECT name, age FROM Role WHERE id='3'  AND lv='14'
         reader = db.SelectWhere("MyRole",
             new string[] { "name", "age" },
             new string[] { "id", "lv" },
             new string[] { "=", "=" },
             new string[] { "", "" }
             );
         if (reader.HasRows)
         {
             reader.Read();
             print(reader.GetString(reader.GetOrdinal("name")));
             print(reader.GetInt32(reader.GetOrdinal("age")));
         }

         CloseDB();
     }

     /// <summary>
     /// 查找多个数据
     /// </summary>
     private void SelectData()
     {
        // 打开数据库
             OpenDB();

             //reader = db .Select( "Role" , "id" , "2" );// 查询所有id 为 2的数据
             //reader = db .Select( "Role" , "id" , ">" , "1" ); // 查询所有id>1的数据
             //reader = db .ReadFullTable("Role"); // 读取整张表
             //reader = db .SelectOrderASC( "Role" , "age" ); // age从小到大排列
             reader = db .SelectOrderDESC( "MyRole" , "lv" ); //  lv从大到小
             if ( reader.HasRows )
             {
                 while( reader .Read() )
                 {
                     string s = "";
                     s += reader .GetInt32( reader .GetOrdinal( "id" ) ) + " , " ;
                     s += reader .GetString( reader .GetOrdinal( "name" ) ) + " , ";
                     s += reader .GetInt32( reader .GetOrdinal( "age" ) ) + " , ";
                     s += reader .GetInt32( reader .GetOrdinal( "lv" ) ) + " , ";
                     s += reader .GetFloat( reader .GetOrdinal( "exp" ) );
                     print( s );
                 }
             }
             // 关闭数据库
             CloseDB();
     }

     private void OnGUI()
     {
         if (GUILayout.Button("创建MyRole表"))
         {
             CreateTable();
         }
         if (GUILayout.Button("插入数据"))
         {
             InsertData();
         }
         if (GUILayout.Button("删除数据库"))
         {
             DeleteData();
         }
         if (GUILayout.Button("更新数据"))
         {
             UpdateData();
         }
         if (GUILayout.Button("查询数据"))
         {
             SearchData();
         }
         if (GUILayout.Button("多条数据查询"))
         {
             SelectData();
         }
     }

 }

MySQLiteDemo