using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Data.SQLite;
using System.Data;

namespace DeiNiu.Data.BaseObject
{
	public class SQLiteHelper
    {
        //创建数据库文件
        public static void CreateDBFile(string fileName)
        {
            string path = System.Environment.CurrentDirectory + @"/Data/";
            if (!Directory.Exists(path))
            {
                Directory.CreateDirectory(path);
            }
            string databaseFileName = path + fileName;
            if (!File.Exists(databaseFileName))
            {
                SQLiteConnection.CreateFile(databaseFileName);
            }
        }
 
        //生成连接字符串
         private static string CreateConnectionString()
        {
            SQLiteConnectionStringBuilder connectionString = new SQLiteConnectionStringBuilder();
            connectionString.DataSource = @"data/ScriptHelper.db";
 
            string conStr = connectionString.ToString();
            return conStr;
        }
 
        /// <summary>
        /// 对插入到数据库中的空值进行处理
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        public static object ToDbValue(object value)
        {
            if (value == null)
            {
                return DBNull.Value;
            }
            else
            {
                return value;
            }
        }
 
        /// <summary>
        /// 对从数据库中读取的空值进行处理
        /// </summary>
        /// <param name="value"></param>
        /// <returns></returns>
        public static object FromDbValue(object value)
        {
            if (value == DBNull.Value)
            {
                return null;
            }
            else
            {
                return value;
            }
        }
 
        /// <summary>
        /// 执行非查询的数据库操作
        /// </summary>
        /// <param name="sqlString">要执行的sql语句</param>
        /// <param name="parameters">参数列表</param>
        /// <returns>返回受影响的条数</returns>
        public static int ExecuteNonQuery(string sqlString, params SQLiteParameter[] parameters)
        {
            string connectionString=CreateConnectionString();
            using (SQLiteConnection conn = new SQLiteConnection(connectionString))
            {
                conn.Open();
                using (SQLiteCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sqlString;
                    foreach (SQLiteParameter parameter in parameters)
                    {
                        cmd.Parameters.Add(parameter);
                    }
                    return cmd.ExecuteNonQuery();
                }
            }
        }
 
        /// <summary>
        /// 执行查询并返回查询结果第一行第一列
        /// </summary>
        /// <param name="sqlString">SQL语句</param>
        /// <param name="sqlparams">参数列表</param>
        /// <returns></returns>
        public static object ExecuteScalar(string sqlString, params SQLiteParameter[] parameters)
        {
            string connectionString = CreateConnectionString();
            using (SQLiteConnection conn = new SQLiteConnection(connectionString))
            {
                conn.Open();
                using (SQLiteCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sqlString;
                    foreach (SQLiteParameter parameter in parameters)
                    {
                        cmd.Parameters.Add(parameter);
                    }
                    return cmd.ExecuteScalar();
                }
            }
        }
 
        /// <summary>
        /// 查询多条数据
        /// </summary>
        /// <param name="sqlString">SQL语句</param>
        /// <param name="parameters">参数列表</param>
        /// <returns>返回查询的数据表</returns>
        public static DataTable GetDataTable(string sqlString,params SQLiteParameter[] parameters)
        {
            string connectionString = CreateConnectionString();
            using (SQLiteConnection conn = new SQLiteConnection(connectionString))
            {
                conn.Open();
                using (SQLiteCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sqlString;
                    foreach (SQLiteParameter parameter in parameters)
                    {
                        cmd.Parameters.Add(parameter);
                    }
                    DataSet ds = new DataSet();
                    SQLiteDataAdapter adapter = new SQLiteDataAdapter(cmd);
                    adapter.Fill(ds);
                    return ds.Tables[0];
                }
            }
        }
    }
}