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、Ja
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：
/// <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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