操作oracle 写和读可以,修改和删除不能操作,请问是怎么回事?

Statement stmt = myconn.createStatement();
//stmt.executeUpdate("UPDATE TBLUSER SET PASSWORD='XABCA'");   //我把下面的写注释了,然后把 删除的注释拿了就始终不能执行,数据库的权限是 SYSTEM 
 stmt
.execute("insert into TBLUSER( username ,password,question,answer,realname,phone,email,mobilephone,msgwakeup,emailwakeup,companyetchoose ,companyetcode,zipcode,province,city,address,investmoney        ,salesdepartment,partnercode1,partnercode2) values('"
+ username
+ "','"
+ password
+ "','"
+ question
+ "','"
+ answer
+ "','"
+ realname
+ "','"
+ phone
+ "','"
+ email
+ "','"
+ mobilephone
+ "','"
+ msgwakeup
+ "','"
+ emailwakeup
+ "','"
+ companyetchoose
+ "','"
+ companyetcode
+ "','"
+ zipcode
+ "','"
+ province
+ "','"
+ city
+ "','"
+ address
+ "','"
+ investmoney
+ "','"
+ salesdepartment
+ "','"
+ partnercode1
+ "','"
+ partnercode2 + "')");