asp: share a tool class that operates a SQL Server database

1 usingSystem;2 usingSystem.Collections.Generic;3 usingSystem.Linq;4 usingsystem.web;5 usingSystem.Collections;6 usingSystem.Data.SqlClient;7 8  Public classDatabasehelper9 {Ten     Private stringConnectionString =Constants.connectionurl; One      A     //Hidden constructors; -     PrivateDatabasehelper () -     { the     } -  -     PrivateDatabasehelper (stringconnectionString) -     { +          This. connectionString =connectionString; -     } +  A     //default parameter connection database; at      PublicSqlConnection getconnection () -     { -SqlConnection connection =NewSqlConnection ( This. connectionString); -         returnconnection; -     } -  in     //Specifies the connection string to connect to the database; -      PublicSqlConnection getconnection (stringconnectionString) to     { +SqlConnection connection =NewSqlConnection (connectionString); -         returnconnection; the     } *  $     //executes the SQL SELECT query statement, returning the query results in JSON format;Panax Notoginseng      Public stringQuery (SqlConnection connection,stringSQLStatement) { -         stringstr ="["; the  + connection. Open (); ASqlCommand Command =connection. CreateCommand (); theCommand.commandtext =SQLStatement; +SqlDataReader DataReader =command. ExecuteReader (); -         inti =0; $ArrayList ArrayList =NewArrayList (); $          for(i =0; i < Datareader.fieldcount; i++) -         { - Arraylist.add (Datareader.getname (i)); the         } -          while(Datareader.read ())Wuyi         {  thestr + ="{"; -              for(i =0; i < Datareader.fieldcount; i++) Wu             { -str + = Arraylist[i]. ToString () +":"+Datareader[i]. ToString (); About                 if(! (i = = Datareader.fieldcount-1)) $                 { -str + =","; -                 } -             } Astr + ="},"; +         } the datareader.close (); - connection. Close (); $         intindex = str. LastIndexOf (","); thestr =Str. Remove (index); thestr + ="]"; the         returnstr; the     } -  in     //Execute SQL INSERT statement; the      Public voidInsert (SqlConnection connection,stringSQLStatement) the     { About connection. Open (); theSqlCommand Command =connection. CreateCommand (); theCommand.commandtext =SQLStatement; the command. ExecuteNonQuery (); + connection. Close (); -     } the Bayi     //Execute SQL UPDATE statement; the      Public voidUpdate (SqlConnection connection,stringSQLStatement) the     { - connection. Open (); -SqlCommand Command =connection. CreateCommand (); theCommand.commandtext =SQLStatement; the command. ExecuteNonQuery (); the connection. Close (); the     } -  the     //executes the SQL DELETE statement; the      Public voidDelete (SqlConnection connection,stringSQLStatement) the     {94 connection. Open (); theSqlCommand Command =connection. CreateCommand (); theCommand.commandtext =SQLStatement; the command. ExecuteNonQuery ();98 connection. Close (); About     } - 101     //returns the instance object of the default argument;102      Public Staticdatabasehelper getinstance ()103     {104         return NewDatabasehelper (); the     }106 107     //returns an instance object of the specified argument;108      Public StaticDatabasehelper getinstance (stringconnectionString)109     { the         return NewDatabasehelper (connectionString);111     } the}

asp: share a tool class that operates a SQL Server database