C # Examples of database connection operations

An XML file was added to the program: app. config

<?xml version= "1.0"?>

<configuration>

<configSections>

<sectiongroup name= "usersettings" type= "System.Configuration.UserSettingsGroup, System, version=4.0.0.0, Culture =neutral, publickeytoken=b77a5c561934e089 ">

<section name= "message.sysfrm" type= "System.Configuration.ClientSettingsSection, System, version=4.0.0.0, Culture=neutral, publickeytoken=b77a5c561934e089 "allowexedefinition=" Machinetolocaluser "requirePermission=" False "/>

<section name= "Message.system" type= "System.Configuration.ClientSettingsSection, System, version=4.0.0.0, Culture=neutral, publickeytoken=b77a5c561934e089 "allowexedefinition=" Machinetolocaluser "requirePermission=" False "/>

</sectionGroup>

</configSections>

<startup>

<supportedruntime version= "v4.0" sku= ". netframework,version=v4.5 "/>

</startup>

<connectionStrings>

<add name= "connstring" connectionstring= "Initial catalog=message; User Id=sa; pwd=112442; Connect timeout=5; "/>

</connectionStrings>

<userSettings>

<Message.sysFrm>

<setting name= "Sysfirststart" serializeas= "String" >

<value>True</value>

</setting>

<setting name= "comsetting" serializeas= "String" >

<value/>

</setting>

<setting name= "portsetting" serializeas= "String" >

<value/>

</setting>

<setting name= "serversetting" serializeas= "String" >

<value/>

</setting>

</Message.sysFrm>

<Message.system>

<setting name= "comsetting" serializeas= "String" >

<value/>

</setting>

</Message.system>

</userSettings>

</configuration>

namespace message{    class dbhelper    {         private static sysfrm syssetting = new sysfrm ();// Define Application settings File         public static readonly string  connstr =  "Data source="  + sysSetting.serverSetting +  system.configuration.configurationmanager.connectionstrings["ConnString"]. connectionstring;        //         public static int executenonquery (string sqlstr, params sqlparameter[]  param)//executenonquery Returns the number of rows affected by the statement and returns if a SELECT statement -1;        {             int res = 0;             using  (SqlconNection conn = new sqlconnection ())              {                 conn. connectionstring = connstr;                 using  (Sqlcommand cmd = new sqlcommand ())                  {                     cmd. commandtext = sqlstr;                     cmd. connection = conn;                     if  (param != null) &NBSP;&NBSP;&NBsp;                      cmd. Parameters.addrange (param);//The  sqlparameter is already included in another  SqlParameterCollection .                      //  Summary: Adds an array of values to the end of  System.Data.SqlClient.SqlParameterCollection .                      //  Parameters: Values: The  System.Data.SqlClient.SqlParameter  value to add.                                           try                     {                         conn. Open ();                         res = cmd. ExecuteNonQuery ();                     }                                              catch  (Exception ex)                      {                         mesSagebox.show (ex. Message);                     }                     //cmd. Parameters.clear ();//The  sqlparameter is already included in another  SqlParameterCollection . Can solve the problem of error, but whether the impact of performance is still to be verified                      return res;                 }             }        }        public  static object executescalar (String sqlstr, params sqlparameter[] param)// Executes the query and returns the first row and first column of the query results &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;{&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&Nbsp;     using  (Sqlconnection conn = new sqlconnection ())             {                 conn. connectionstring = connstr;                 using  (Sqlcommand cmd = new sqlcommand ())                  {                     cmd. connection = conn;                     cmd. commandtext = sqlstr;                     if  (param != null)                          cmd. Parameters.addrange (param);                     conn. Open ();//Opening Database                                          return cmd. ExecuteScalar ();                                      }            }         }       &nBsp;public static sqldatareader executereader (String sqlstr, params sqlparameter [] param)         {             sqlconnection conn = new sqlconnection ();             conn. connectionstring = connstr;             using  (Sqlcommand cmd = new sqlcommand ())              {                 cmd. connection = conn;                 cmd. commandtext = sqlstr;                 if  (param != null)                      cmd. Parameters.addrange (param);                                  try                {                      conn. Open ();                                }                 catch  (System.exception ex)                 {                     messagebox.show ("Error getting database server and instance in network! "  + ex. ToString (),  "hint", messageboxbuttons.ok, messageboxicon.information);                     return null;                 }                 sqldatareader dr  = cmd. ExecuteReader (commandbehavior.closeconnection);                 return dr;             }        }         public static DataTable DataAdapter (String sqlstr, params sqlparameter[] param)          {                  sqldataadapter da = new sqldataadapter (SQLSTR,&NBSP;CONNSTR);             datatable dt = new datatable () ;             da. SelectCommand.Parameters.AddRange (param);             //dataset ds = new dataset ();             da. Fill (DT);            int ias =    dt. rows.count;            for  (int i =  0; i <&nBsp;dt. Rows.count; ++i)             {                 datarow dr =  dt. rows[i];            }             return dt;         }    }    }

This article is from the "Radisson Blu Still" blog, please be sure to keep this source http://wangwentao2015.blog.51cto.com/5601365/1689848

C # Examples of database connection operations