c# - The variable name '@VarName' has already been declared Issue -


i inserting multiple items table based on selection drop down list. when select 1 item drop down works fine when select multiple items error

the variable name '@compname' has been declared. variable names must unique within query batch or stored procedure.

what doing wrong? here code

protected void dv_test_iteminserting(object sender, detailsviewinserteventargs e)     {         foreach (listitem listitem in cblcustomerlist.items)         {             if (listitem.selected)             {                 string name= listitem.value;                 sqlcon.open();                 string compname= ((textbox)dv_test.findcontrol("txtcompname")).text.tostring();                 string num = ((textbox)dv_test.findcontrol("txtnum")).text.tostring();                 sqlcommand cmd = new sqlcommand("select compnamefrom mytable compname= '" + compname+ "' , num = '" + num + "' , name= '" + name+ "'    ", sqlcon);                 sqldatareader dr = cmd.executereader();                 if (dr.read())                 {                     lblmsg.text = "not valid";                 }                 else                 {                     dr.close();                      sqlcmd.commandtext = "insert mytable(compname, num, name) values(@compname, @num, @name)";                     sqlcmd.parameters.add("@compname", sqldbtype.varchar).value = compname;                     sqlcmd.parameters.add("@num", sqldbtype.varchar).value = num;                     sqlcmd.connection = sqlcon;                                      sqlcmd.executenonquery();                     dv_test.changemode(detailsviewmode.insert);                     sqlcon.close();                 }                 sqlcon.close();                            }           }  }

you adding paramters @compname , @num query every time through loop.

you need move call add outside loop , use following update them:

sqlcmd.parameters["@compname"].value = compname; sqlcmd.parameters["@num"].value = num;

so code becomes:

sqlcmd.commandtext = "insert mytable(compname, num, name) values(@compname, @num, @name)"; sqlcmd.parameters.add("@compname", sqldbtype.varchar); sqlcmd.parameters.add("@num", sqldbtype.varchar);  foreach (listitem listitem in cblcustomerlist.items) {     if (....)     {         ....     }     else     {         dr.close();          sqlcmd.parameters["@compname"].value = compname;         sqlcmd.parameters["@num"].value = num;         sqlcmd.connection = sqlcon;                          sqlcmd.executenonquery();         dv_test.changemode(detailsviewmode.insert);         sqlcon.close();     }  }

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