一、NuGet引入SQLite库

在VS菜单:工具→NuGet包管理器→管理解决方案的NuGet程序包 打开NuGet解决方案窗口。

搜索 sqlite,选择官方的库安装到指定的项目中。:

提示:System.Data.SQLite 分为 x86 和 x64 版本,这里推荐使用NuGet自动安装。使用 Any CPU 编译的时候,会自动拷贝32位和64位 Interop DLL文件到子目录中。程序运行的时候会根据电脑的运行环境自动选择合适的dll。

二、DBHelper类库

using System.Collections.Generic;
using System.Data;
using System.Data.SQLite;
using System.Configuration;
using System.Data.SqlClient;
//using MySql.Data.MySqlClient;

namespace ConsoleApp5
{
    public class DBHelper
    {
        private readonly static string connStr = ConfigurationManager.ConnectionStrings["Data Source=mesclient.sqlite;Version=3"].ConnectionString;

        //获取 appsetting 设置的值
        //private readonly static string appStr = ConfigurationManager.AppSettings["TestKey"];

        //获取 connection 对象
        public static IDbConnection CreateConnection()
        {
            IDbConnection conn = new SQLiteConnection(connStr);//MySqlConnection //SqlConnection
            conn.Open();
            return conn;
        }

        //执行非查询语句
        public static int ExecuteNonQuery(IDbConnection conn, string sql, Dictionary<string, object> parameters)
        {
            using (IDbCommand cmd = conn.CreateCommand())
            {
                cmd.CommandText = sql;
                foreach (KeyValuePair<string, object> keyValuePair in parameters)
                {
                    IDbDataParameter parameter = cmd.CreateParameter();
                    parameter.ParameterName = keyValuePair.Key;
                    parameter.Value = keyValuePair.Value;
                    cmd.Parameters.Add(parameter);
                }
                return cmd.ExecuteNonQuery();
            }
        }

        //执行非查询语句-独立连接
        public static int ExecuteNonQuery(string sql, Dictionary<string, object> parameters)
        {
            using (IDbConnection conn = CreateConnection())
            {
                return ExecuteNonQuery(conn, sql, parameters);
            }
        }

        //查询首行首列
        public static object ExecuteScalar(IDbConnection conn, string sql, Dictionary<string, object> parameters)
        {
            using (IDbCommand cmd = conn.CreateCommand())
            {
                cmd.CommandText = sql;
                foreach (KeyValuePair<string, object> keyValuePair in parameters)
                {
                    IDbDataParameter parameter = cmd.CreateParameter();
                    parameter.ParameterName = keyValuePair.Key;
                    parameter.Value = keyValuePair.Value;
                    cmd.Parameters.Add(parameter);
                }
                return cmd.ExecuteScalar();
            }
        }

        //查询首行首列-独立连接
        public static object ExecuteScalar(string sql, Dictionary<string, object> parameters)
        {
            using (IDbConnection conn = CreateConnection())
            {
                return ExecuteScalar(conn, sql, parameters);
            }
        }

        //查询表
        public static DataTable ExecuteQuery(IDbConnection conn, string sql, Dictionary<string, object> parameters)
        {
            DataTable dt = new DataTable();
            using (IDbCommand cmd = conn.CreateCommand())
            {
                cmd.CommandText = sql;
                foreach (KeyValuePair<string, object> keyValuePair in parameters)
                {
                    IDbDataParameter parameter = cmd.CreateParameter();
                    parameter.ParameterName = keyValuePair.Key;
                    parameter.Value = keyValuePair.Value;
                    cmd.Parameters.Add(parameter);
                }
                using (IDataReader reader = cmd.ExecuteReader())
                {
                    dt.Load(reader);
                }
            }

            return dt;
        }

        //查询表--独立连接
        public static DataTable ExecuteQuery(string sql, Dictionary<string, object> parameters)
        {
            using (IDbConnection conn = CreateConnection())
            {
                return ExecuteQuery(conn, sql, parameters);
            }
        }
    }
}


三、基本使用

1. 判断数据文件是否存在

/// <summary>
/// 检查数据库是否存在不存在创建
/// </summary>
/// <returns></returns>
public static bool CheckDataBase()
{
    try
    {
        //判断数据文件是否存在
        bool dbExist = File.Exists("mesclient.sqlite");
        if (!dbExist)
        {
            SQLiteConnection.CreateFile("mesclient.sqlite");
        }


        return true;
    }
    catch (Exception)
    {
        return false;
    }


}

2. 判断表是否存在

/// <summary>
/// 检查数据表是否存在,不存在创建
/// </summary>
/// <returns></returns>
public static bool CheckDataTable(string connStr)
{
    try
    {
        using (SQLiteConnection conn = new SQLiteConnection(connStr))
        using (SQLiteCommand cmd = conn.CreateCommand())
        {
            conn.Open();
            cmd.CommandText = "SELECT count(*) FROM sqlite_master WHERE type = 'table' AND name = 'serverinfo'";
            object ob = cmd.ExecuteScalar();
            long tableCount = Convert.ToInt64(ob);
            if (tableCount == 0)
            {
                //创建表
                cmd.CommandText = @"
            BEGIN;
                create table serverinfo 
                (Id INTEGER PRIMARY KEY AUTOINCREMENT,Name TEXT,
                Url text,DelayTime integer,UsageCounter INTEGER,
                 Status integer,CreateTime DATETIME);
                CREATE UNIQUE INDEX idx_serverInfo ON serverinfo (Name);
            COMMIT;
            ";
                //此语句返回结果为0
                int rowCount = cmd.ExecuteNonQuery();
                return true;
            }
            else if (tableCount > 1)
            {
                return false;
            }
            else
            {
                return true;
            }
        }
    }
    catch (Exception ex)
    {
        return false;
    }
}

3. 查询

string sql = "SELECT * FROM serverinfo WHERE Name =@ServerName AND Url = @Url and date(CreateTime)=date(@Date);";
Dictionary<string, object> parameters = new Dictionary<string, object>();
parameters.Add("ServerName",endpointElement.Name);
parameters.Add("Url", endpointElement.Address);
parameters.Add("Date", DateTime.Now.ToString("yyyy-MM-dd"));
DataTable dt=SqliteHelper.ExecuteQuery(connStr, sql, parameters);
if (dt.Rows.Count>0)
{
    UsageCounter = dt.Rows[0].Field<long>("UsageCounter");
    GetTime = dt.Rows[0].Field<DateTime>("CreateTime");
}

4. 新增/修改

//存在更新,不存在插入
string updateSql = "REPLACE INTO serverinfo(Name,Url,DelayTime,UsageCounter, Status,CreateTime) VALUES(@Name,@Url,@DelayTime,@UsageCounter,@Status, @CreateTime)";
Dictionary<string, object> ups = new Dictionary<string, object>();
ups.Add("Name", name);
ups.Add("Url", url);
ups.Add("DelayTime", delayTime);
ups.Add("UsageCounter", usageCounter);
ups.Add("Status", status);
ups.Add("CreateTime", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"));
int count= SqliteHelper.ExecuteNonQuery(connStr, updateSql, ups);
if (count>0)
{
    return true;
}
else
{
    return false;
}

5. 删除

//删除记录
string updateSql =
    "DELETE FROM serverinfo where content=@Content and flag=@Flag;";
Dictionary<string, object> updateParameters = new Dictionary<string, object>();
updateParameters.Add("Content", Content);
updateParameters.Add("Flag", Flag);
int count = SqliteHelper.ExecuteNonQuery(connStr, updateSql, updateParameters);
if (count > 0)
{
    return true;
}
else
{
    return false;
}

四、参考文章

  1. Create SQLite Database and table

  2. Writing to a SQLite Database in C#

  3. SQLite with VS2012 and .NET 4.5 — ANY CPU Build

  4. how to check if a table exists in C#

  5. SQLite auto increment issue

  6. Inserting a date to SQLite

  7. SQLite REPLACE Statement

  8. sqlite select with condition on date

  9. Using SQLite how do I index columns in a CREATE TABLE statement?


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