java - Check for duplicates in database before inserting -

i need check in database if record exist before insert table. have 2 tables, 1 insert data , 1 log table referenced main table. in log table have id, date_import , file_import. want check if file_import exist.

here scratch code:

    //date         dateformat datef = new simpledateformat("dd.mm.yyyy");         date date = new date(); //date          //db init         string url = "jdbc:mysql://192.168.1.128:3306";         connection con = (connection) drivermanager.getconnection(url,user,pass);         statement stmt = (statement) con.createstatement(resultset.type_scroll_sensitive, resultset.concur_updatable);         statement stmt1 = (statement) con.createstatement(resultset.type_scroll_sensitive, resultset.concur_updatable);         string mysql_log = ("create table if not exists dbtest.t_ajpes_tr_log"             + "(id int unsigned primary key auto_increment, date_import varchar(45),"             + "file_import varchar(75)) engine = innodb");         string mysql_new_table = ("create table if not exists dbtest.t_ajpes_tr "             + "(row_count int primary key auto_increment,"             + "rn char(15),sspre char(5),reg char(5),eno varchar(10),davcna varchar(15),ime varchar(75),"             + "priimek varchar(75),id_log int unsigned,"             + "constraint foreign key(id_log) references t_ajpes_tr_log(id) on delete cascade on update cascade) engine = innodb");          stmt1.executeupdate(mysql_log);         resultset uprs1 = stmt1.executequery("select * dbtest.t_ajpes_tr_log");         stmt.executeupdate(mysql_new_table);         resultset uprs = stmt.executequery("select * dbtest.t_ajpes_tr"); //select init  //read file                 file folder = new file(readfolder);         string[] filename = folder.list();          (;k<filename.length;k++) {             name = filename[k];             if (name.contains(".xml")) {             fileinputstream fstream = new fileinputstream(readfolder + name);             datainputstream in = new datainputstream(fstream);             bufferedreader br = new bufferedreader(new inputstreamreader(in)); //read file             uprs.next();             file_exists = uprs1.getstring("file_import");              if (!file_exists.equals(name)) {                 uprs1.afterlast();                 uprs1.movetoinsertrow();                 uprs1.updatestring("date_import",datef.format(date));                 uprs1.updatestring("file_import",name);                 uprs1.insertrow();                 i=0; 

i may have misunderstood question, if send

select * dbtest.t_ajpes_tr_log file_import='myfilename.xml'; 

to database, you'll either empty result set (= actual filename new) or set 1..n entries (= filename known , has been logged 1..n times).

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put in quotes, knubo said:

string query = string.format(     "select * dbtest.t_ajpes_tr_log file_import='%s'", name); uprs1 = stmt1.executequery(query);