c# - Delete record from a sql table by selecting from gridview on button click -
i want delete record datagridview that's in 1 form pressing button in form. getting nullreferenceexception unhandled error. new c# if write me correct code appreciate it.
here's got far.
private void button1_click(object sender, eventargs e) { sqlconnection con = new sqlconnection(@" data source=home-d2cadc8d4f\sql;initial catalog=motociclete;integrated security=true"); sqlcommand cmd = new sqlcommand(); (int = 0; < datagridview1.rows.count; i++) { datagridviewrow dr = datagridview1.rows[i]; if (dr.selected == true) { datagridview1.rows.removeat(i); try { con.open(); cmd.commandtext = "delete motociclete codm=" + + ""; cmd.executenonquery(); con.close(); } catch (exception ex) { messagebox.show(ex.tostring()); } } } this.close(); }
just invert verse of loop.
(int = datagridview1.rows.count - 1; >= 0 ; i--) in way loop not affected changing number of rows
also. case not open/close connection @ every command execution, , command execution more performant if use parameter in way
using(sqlconnection con = new sqlconnection(@" data source=home-d2cadc8d4f\sql;initial catalog=motociclete;integrated security=true")) using(sqlcommand cmd = new sqlcommand("delete motociclete codm=@id", con)) { con.open(); cmd.parameters.addwithvalue("@id", 0); (int = datagridview1.rows.count-1; >= 0; i++) { datagridviewrow dr = datagridview1.rows[i]; if (dr.selected == true) { datagridview1.rows.removeat(i); cmd.parameters["@id"].value = i; cmd.executenonquery(); } } }
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