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
- 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
- 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：
////// SQLite 操作类 /// class SqLiteHelper { ////// 数据库连接定义 /// private SQLiteConnection dbConnection; ////// SQL命令定义 /// private SQLiteCommand dbCommand; ////// 数据读取定义 /// private SQLiteDataReader dataReader; ////// 构造函数 /// /// 连接SQLite库字符串 public SqLiteHelper(string connectionString) { try { dbConnection = new SQLiteConnection(connectionString); dbConnection.Open(); }catch(Exception e) { Log(e.ToString()); } } ////// 执行SQL命令 /// ///The query. /// SQL命令字符串 public SQLiteDataReader ExecuteQuery(string queryString) { try { dbCommand = dbConnection.CreateCommand(); dbCommand.CommandText = queryString; dataReader = dbCommand.ExecuteReader(); }catch(Exception e) { Log(e.Message); } return dataReader; } ////// 关闭数据库连接 /// 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; } ////// 读取整张数据表 /// ///The full table. /// 数据表名称 public SQLiteDataReader ReadFullTable(string tableName) { string queryString = "SELECT * FROM " + tableName; return ExecuteQuery(queryString); } ////// 向指定数据表中插入数据 /// ///The values. /// 数据表名称 /// 插入的数值 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); } ////// 更新指定数据表内的数据 /// ///The values. /// 数据表名称 /// 字段名 /// 字段名对应的数据 /// 关键字 /// 关键字对应的值 /// 运算符：=,<,>,...，默认“=” 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); } ////// 删除指定数据表内的数据 /// ///The values. /// 数据表名称 /// 字段名 /// 字段名对应的数据 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); } ////// 删除指定数据表内的数据 /// ///The values. /// 数据表名称 /// 字段名 /// 字段名对应的数据 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); } ////// 创建数据表 /// + ///The table. /// 数据表名 /// 字段名 /// 字段名类型 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); } ////// Reads the table. /// ///The table. /// Table name. /// Items. /// Col names. /// Operations. /// Col values. 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); } ////// 本类log /// /// 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","[email protected]" });
sql.InsertValues("table1", new string[] { "2", "李四", "25", "[email protected]" });
//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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