C# SQLite数据库入门使用说明

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,  > parameters)
  {
   using (IDbCommand cmd = conn.CreateCommand())
   {
    cmd.CommandText = sql;
    foreach (KeyValuePair<string,  > 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,  > parameters)
  {
   using (IDbConnection conn = CreateConnection())
   {
    return ExecuteNonQuery(conn, sql, parameters);
   }
  }

  //查询首行首列
  public static   ExecuteScalar(IDbConnection conn, string sql, Dictionary<string,  > parameters)
  {
   using (IDbCommand cmd = conn.CreateCommand())
   {
    cmd.CommandText = sql;
    foreach (KeyValuePair<string,  > 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   ExecuteScalar(string sql, Dictionary<string,  > parameters)
  {
   using (IDbConnection conn = CreateConnection())
   {
    return ExecuteScalar(conn, sql, parameters);
   }
  }

  //查询表
  public static DataTable ExecuteQuery(IDbConnection conn, string sql, Dictionary<string,  > parameters)
  {
   DataTable dt = new DataTable();
   using (IDbCommand cmd = conn.CreateCommand())
   {
    cmd.CommandText = sql;
    foreach (KeyValuePair<string,  > 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,  > parameters)
  {
   using (IDbConnection conn = CreateConnection())
   {
    return ExecuteQuery(conn, sql, parameters);
   }
  }
 }
}

/// <summary>
/// 检查数据库是否存在不存在创建
/// </summary>
/// <returns></returns>
public static bool CheckData ()
{
 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;
 }
}

/// <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\'\";
     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;
 }
}

string sql = \"SELECT * FROM serverinfo WHERE Name =@ServerName AND Url = @Url and date(CreateTime)=date(@Date);\";
Dictionary<string,  > parameters = new Dictionary<string,  >();
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\");
}

//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,  > ups = new Dictionary<string,  >();
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;
}

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