SqlServerDatabase.cs

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using System;using System.Configuration;using System.Data;using System.Data.SqlClient;public class SqlServerDatabase{    #region 变量    private static string _connectionString;    private static SqlConnection _connection;    private static SqlCommand _command;    #endregion    #region 实例化    private static SqlServerDatabase _instance;    public static SqlServerDatabase Instance => _instance ?? (_instance = new SqlServerDatabase());    public SqlServerDatabase()    {        _instance = this;    }    public SqlServerDatabase(string connName)    {        _instance = this;        Init(connName);    }    public SqlServerDatabase(string dataSource, string initialCatalog, string username, string password)    {        _instance = this;        Init(dataSource, initialCatalog, username, password);    }    #endregion    #region 公共调用方法    //初始化    public void Init(string connName)    {        _connectionString = ConfigurationManager.ConnectionStrings[connName].ToString();    }    //初始化    public void Init(string dataSource, string initialCatalog, string username, string password)    {        _connectionString = $"Data Source={dataSource};Initial Catalog={initialCatalog};user id={username};pwd={password}";    }    //打开    public void Open()    {        _connection = new SqlConnection(_connectionString);        _connection.Open();        _command = new SqlCommand { Connection = _connection };    }    //关闭    public void Close() => _connection.Close();    public DataTable GetTable(string sql)    {        var dt = new DataTable();        try        {            _command.CommandText = sql;            var dr = _command.ExecuteReader();            dt.Load(dr);            dr.Close();        }        catch        {            // ignored        }        return dt;    }    public int Perform(string sql)    {        try        {            _command.CommandText = sql;            return _command.ExecuteNonQuery();        }        catch        {            return 0;            // ignored        }    }    public int Perform(string sql, SqlParameter[] parameters = null)    {        var result = -1;        try        {            _command.CommandText = sql;            if (parameters != null)            {                _command.Parameters.AddRange(parameters);            }            result = _command.ExecuteNonQuery();        }        catch        {            // ignored        }        return result;    }    public bool Perform(string sql, out string err)    {        var result = false;        err = null;        try        {            _command.CommandText = sql;            _command.ExecuteNonQuery();            result = true;        }        catch (Exception ex)        {            err = ex.Message;        }        return result;    }    public string Query(string sql)    {        string result = null;        try        {            _command.CommandText = sql;            result = _command.ExecuteScalar().ToString();        }        catch        {            // ignored        }        return result;    }    #endregion}
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