全局 SqlConnection
class SqlHelper { public static SqlConnection conn; public static SqlConnection Open(string connStr) { if (!string.IsNullOrEmpty(connStr)) { SqlConnection conn = new SqlConnection(connStr); try { conn.Open(); return conn; } catch (Exception) { } } return null; } public static bool Open(SqlConnection conn) { if (conn != null && conn.State != ConnectionState.Open) { try { conn.Open(); return true; } catch (Exception ex) { MessageBox.Show(ex.Message); return false; } } return false; } public static DataTable DB_Select(SqlConnection conn, string text, params SqlParameter[] parameters) { if (Open(conn)) { DataTable dt = new DataTable(); SqlDataAdapter da = new SqlDataAdapter(text, conn); da.Fill(dt); return dt; } return null; } public static void Close(SqlConnection conn) { if (conn != null && conn.State != ConnectionState.Closed) conn.Close(); } }