SQLiteDatabase.cs

using System;
using System.Data;// DataTable
using System.Data.SQLite;
using System.IO;

// SQLiteConnection,SQLiteCommand,SQLiteDataReader

/// <summary>
/// SQLiteDatabase 的摘要说明
/// </summary>
public class SQLiteDatabase
{
#region 变量
private SQLiteConnection _dbConnection;

#endregion

#region 属性
public string FileName { get; set; }
public string DataSource => $"Data Source={FileName};Version=3;";

#endregion

#region 实例化
private static SQLiteDatabase _instance;
public static SQLiteDatabase Instance => _instance ?? (_instance = new SQLiteDatabase());
public SQLiteDatabase()
{
FileName = "SQLite.s3db";
}
public SQLiteDatabase(string fileName)
{
FileName = fileName;
}

#endregion

public void Open()
{
if (!File.Exists(FileName)) SQLiteConnection.CreateFile(FileName);
_dbConnection = new SQLiteConnection(DataSource);
_dbConnection.Open();
}

public void Close()
{
_dbConnection.Close();
}

public DataTable GetDataTable(string sql)
{
var dt = new DataTable();
try
{
var cmd = new SQLiteCommand(_dbConnection) { CommandText = sql };
var dr = cmd.ExecuteReader();
dt.Load(dr);
dr.Close();
}
catch
{
// ignored
}
return dt;
}

public int Perform(string sql)
{
var result = -1;
try
{
var cmd = new SQLiteCommand(_dbConnection) { CommandText = sql };
result = cmd.ExecuteNonQuery();
}
catch
{
// ignored
}
return result;
}

public bool Perform(string sql, out string err)
{
var result = false;
err = null;
try
{
var cmd = new SQLiteCommand(_dbConnection) { CommandText = sql };
cmd.ExecuteNonQuery();
result = true;
}
catch (Exception ex)
{
err = ex.Message;
}
return result;
}

public string Query(string sql)
{
string result = null;
try
{
var cmd = new SQLiteCommand(_dbConnection) { CommandText = sql };
result = cmd.ExecuteScalar().ToString();
}
catch
{
// ignored
}
return result;
}

}