java - How to guess or determine a SQL identity field and avoid duplicate -


i trying avoid duplicate updates data, know if there way update 1 row field without updating piece of data in subsequent row. here scenario, have code:

string sql = "update vagas set matricula ='" +txtmat.gettext()     + "'  curso ='" +combocurso.getselecteditem().tostring()     + "' , turma='"+turmacombo.getselecteditem().tostring()+"'"; pstmt = conlogin.preparestatement(sql); pstmt.execute(); joptionpane.showmessagedialog(null, "vagas atualizados com sucesso!");

i want update field matricula (which means student subscription id), course (curso) equals combocurso.getselecteditem().tostring() combobox , turma (which means course classroom filled group) equals combocurso.getselecteditem().tostring() combobox.

everything updates ok except 1 issue, example have matricula rows same name (1acc) represents 2 classroom vacancies. when call update fill both of them matricula number not desired since want fill 1 vacancy, both have same names fill both.

so there first field(column) named vagas (not table name column name) int identity (1,1) field, , want fill 1 field when call update command. trying comparing vagas column cant seem find way it.

if have multiple records meet criteria, , want 1 of records updated, have insufficient criteria update. isn't code problem, it's design problem... need choose how wish pick 1 record update out of many records selecting. how want pick record update?

if answer doesn't matter, use aggregate function on identity column constraint, example:

where ... , vagas = (select min(vagas) vagas ...)

note "..." represents conditions you're using. snippet of code picks vagas record lowest vagas value (via select subquery).


Comments

Post a Comment

Popular posts from this blog

.htaccess - First slash is removed after domain when entering a webpage in the browser -

sometimes when hit address of webpage in browser, removes first slash after domain. examples: www.mywebsite.com/scripts/script_6.php -> trying load www.mywebsite.comscripts/script_6.php www.mywebsite.com/test.php -> trying load www.mywebsite.comtest.php after entering again, loads page. a .htaccess settings must wrong: rewritebase / errordocument 404 http://www.mywebsite.com/oops.php errordocument 401 /notallowed.php rewriteengine on # turn on rewriting engine #gzip <ifmodule mod_deflate.c> addoutputfilterbytype deflate text/text text/html text/plain text/xml text/css application/x- javascript application/javascript </ifmodule> #end gzip rewritecond %{http_host} ^mywebsite\.com rewriterule ^(.*)$ http://www.mywebsite.com$1 [r=permanent,l] directoryindex index6.php rewriterule ^termsofuse/?$ termsofuse.php [nc,l] # handle requests "adpolicy" rewriterule ^privacy-policy/?$ privacy-policy.php [nc,l] # handle requ...
Read more

Socket.connect doesn't throw exception in Android -

if put nonsense url no exception thrown , none of rest of code executed not rest of asynctask called method connects. try { socketcliente.connect(new inetsocketaddress("f", port), 2000); } catch (unknownhostexception e) { geterror("host doesn't exist"); return -1; } catch (ioexception e) { geterror("could not connect: host down"); return -1; } add catch statement. catch ( exception e ) { log.d(tag, e.getmessage(),e); toast.maketext(getapplicationcontext(), "unexpected error:" + e.getmessage(), toast.length_long).show(); } this write log , pop toast tell what's going on.
Read more

SPSS keyboard combination alters encoding -

my question not have programming practical issue on spss. accident keyword combination cannot remember because did not intend press changed encoding in spss , text in data in different language english shown small boxes. nevertheless, when kind of analysis performed different language text shown in output. does know reason? tried change encoding did not produce result. first, @ edit > options , see whether setting unicode or locale. might fix it. if have text in multiple languages, want unicode. otherwise, may have specific locale set wrong. can change set locale, need know locale want use.
Read more