sql server - c# windows forms logout -
how make logout button in c# windows forms closes mssql connection.
i have login form sends username , password 1 form another. connection string on form2 placed under public partial class , looks this:
public static sqlconnection con = new sqlconnection(@"data source=" + globalvariables.hosttxt + "," + globalvariables.porttxt + "\\sqlexpress;database=ha;persist security info=false; uid='" + globalvariables.user + "' ; pwd='" + globalvariables.psw + "'"); sqlcommand mysqlcmd = con.createcommand(); i've created logout button on form2 goes first login form, doesn't seem close sqlconnection. can press login button again without entering user , password , through form2 again.
so first time have enter username , password , second time dont need to.
the code use logout button is:
con.close(); this.close(); form fmlogind = new logind(); fmlogind.show(); here whole code on second form:
using system; using system.collections.generic; using system.componentmodel; using system.data; using system.drawing; using system.linq; using system.text; using system.windows.forms; using system.data.sqlclient; using system.io; namespace windowsformsapplication1 { public partial class form1 : form { public static sqlconnection con = new sqlconnection(@"data source=" + globalvariables.hosttxt + "," + globalvariables.porttxt + "\\sqlexpress;database=ha;persist security info=false; uid='" + globalvariables.user + "' ; pwd='" + globalvariables.psw + "'"); sqlcommand mysqlcmd = con.createcommand(); public form1() { initializecomponent(); this.text ="easyaud"; } public void form1_load(object sender, eventargs e) { easyaudtoolstripmenuitem.text = globalvariables.user; combobox4.items.add("1"); combobox4.items.add("2"); mysqlcmd.commandtext = "select distinct firma app"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { combobox1.items.add(firmareader["firma"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct type app"; con.open(); sqldatareader typereader = mysqlcmd.executereader(); while (typereader.read()) { combobox2.items.add(typereader["type"]); } typereader.close(); con.close(); } private void combobox1_selectedindexchanged_1(object sender, eventargs e) { listbox1.items.clear(); combobox3.items.clear(); if (combobox1.text != "" && combobox2.text == "" && combobox3.text == "") { string firma = combobox1.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app firma = '" + firma + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app firma = '" + firma + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text == "" && combobox2.text != "" && combobox3.text == "") { string type = combobox2.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app type = '" + type + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app type = '" + type + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text == "" && combobox2.text == "" && combobox3.text != "") { string farve = combobox3.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app farve = '" + farve + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app farve = '" + farve + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text != "" && combobox2.text != "" && combobox3.text != "") { string firma = combobox1.selecteditem.tostring(); string type = combobox2.selecteditem.tostring(); string farve = combobox3.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app firma = '" + firma + "' , type ='" + type + "' , farve ='" + farve + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app firma = '" + firma + "' , type ='" + type + "' , farve ='" + farve + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text != "" && combobox2.text != "" && combobox3.text == "") { string firma = combobox1.selecteditem.tostring(); string type = combobox2.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app firma = '" + firma + "' , type ='" + type + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app firma = '" + firma + "' , type ='" + type + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text != "" && combobox2.text == "" && combobox3.text != "") { string firma = combobox1.selecteditem.tostring(); string farve = combobox3.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app firma = '" + firma + "' , farve ='" + farve + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app firma = '" + firma + "' , farve ='" + farve + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text == "" && combobox2.text != "" && combobox3.text != "") { string type = combobox2.selecteditem.tostring(); string farve = combobox3.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app type = '" + type + "' , farve ='" + farve + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app type = '" + type + "' , farve ='" + farve + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } } private void combobox2_selectedindexchanged(object sender, eventargs e) { listbox1.items.clear(); combobox3.items.clear(); if (combobox1.text != "" && combobox2.text == "" && combobox3.text == "") { string firma = combobox1.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app firma = '" + firma + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app firma = '" + firma + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text == "" && combobox2.text != "" && combobox3.text == "") { string type = combobox2.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app type = '" + type + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app type = '" + type + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text == "" && combobox2.text == "" && combobox3.text != "") { string farve = combobox3.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app farve = '" + farve + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app farve = '" + farve + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text != "" && combobox2.text != "" && combobox3.text != "") { string firma = combobox1.selecteditem.tostring(); string type = combobox2.selecteditem.tostring(); string farve = combobox3.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app firma = '" + firma + "' , type ='" + type + "' , farve ='" + farve + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app firma = '" + firma + "' , type ='" + type + "' , farve ='" + farve + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text != "" && combobox2.text != "" && combobox3.text == "") { string firma = combobox1.selecteditem.tostring(); string type = combobox2.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app firma = '" + firma + "' , type ='" + type + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app firma = '" + firma + "' , type ='" + type + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text != "" && combobox2.text == "" && combobox3.text != "") { string firma = combobox1.selecteditem.tostring(); string farve = combobox3.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app firma = '" + firma + "' , farve ='" + farve + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app firma = '" + firma + "' , farve ='" + farve + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } if (combobox1.text == "" && combobox2.text != "" && combobox3.text != "") { string type = combobox2.selecteditem.tostring(); string farve = combobox3.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct ha app type = '" + type + "' , farve ='" + farve + "'"; con.open(); sqldatareader firmareader = mysqlcmd.executereader(); while (firmareader.read()) { listbox1.items.add(firmareader["ha"]); } firmareader.close(); con.close(); mysqlcmd.commandtext = "select distinct farve app type = '" + type + "' , farve ='" + farve + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } } private void combobox3_selectedindexchanged(object sender, eventargs e) { } private void listbox1_selectedindexchanged(object sender, eventargs e) { combobox3.items.clear(); string ha = listbox1.selecteditem.tostring(); mysqlcmd.commandtext = "select distinct farve app ha = '" + ha + "'"; con.open(); sqldatareader farvereader = mysqlcmd.executereader(); while (farvereader.read()) { combobox3.items.add(farvereader["farve"]); } farvereader.close(); con.close(); } private void combobox3_selectedindexchanged_1(object sender, eventargs e) { } private void combobox4_selectedindexchanged(object sender, eventargs e) { } private void button1_click(object sender, eventargs e) { listbox1.items.clear(); combobox1.selectedindex = -1; combobox2.selectedindex = -1; combobox3.selectedindex = -1; combobox4.selectedindex = -1; } private void button2_click(object sender, eventargs e) { if (combobox4.text == "" || combobox3.text == "" || listbox1.text == "") { messagebox.show("ha-valg blev ikke gemt!" + "\n" + "felterne: antal, ha og farve skal udfyldes", "ikke gemt"); } if (combobox4.text != "" && listbox1.text != "") { string ha = listbox1.selecteditem.tostring(); clipboard.settext(combobox4.text + "stk " + ha + " farve " + combobox3.text); } } private void logaftoolstripmenuitem_click(object sender, eventargs e) { this.close(); form fmlogind = new logind(); fmlogind.show(); } private void easyaudtoolstripmenuitem_click(object sender, eventargs e) { } private void luktoolstripmenuitem_click(object sender, eventargs e) { application.exit(); } private void menustrip1_itemclicked(object sender, toolstripitemclickedeventargs e) { } } }
this line of code executes once , only once no matter how many times open form:
public static sqlconnection con = new sqlconnection(@"data source=" + globalvariables.hosttxt + "," + globalvariables.porttxt + "\\sqlexpress;database=ha;persist security info=false; uid='" + globalvariables.user + "' ; pwd='" + globalvariables.psw + "'"); aside use of global variables (bad idea) , use of single static database connection (bad idea), once you've created connection first time always exist static property on type.
from point forward, can enter username , password values like. may updating global variables associated them, you're not updating con variable. right-hand side of expression doesn't hold reference global variables evaluated multiple times, evaluates them once , keeps result of evaluation.
so order of events in case is:
- create connection using supplied username , password.
- open connection.
- use form, connection, etc.
- close connection.
- change username , password variables, not connection.
- re-open original connection, using original connection string.
your best approach fixing remove sqlconnection object static scope. if want try initiate database connection when form loads, in constructor or in form1_load event handler. , instead of re-using same always-open connection throughout application, time need access database should create connection local scope , dispose of you're done it.
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