title: oracle sql developer- ora-12514 error
body: <p>im using oracle sql developer to make my database, but now i stopped to work.
  it wrote this: </p>
  
  <blockquote>
    <p>An error was encountered performing the requested operation:</p>
    
    <p>Listener refused the connection with the following error: ORA-12514,
    TNS:listener does not currently know of service requested in connect
    descriptor  </p>
    
    <p>Vendor code 12514</p>
  </blockquote>
  
  <p>i also tried to make new connection but it didnt help
  pls help me,i dont know what to do, i need this to do my homework</p>
  
  <p>when i tried to change connection it wrote this:</p>
  
  <blockquote>
    <p>An error was encountered performing the requested operation:</p>
    
    <p>ORA-01031: insufficient privileges
    01031. 00000 -  "insufficient privileges"
    *Cause:    An attempt was made to change the current username or password
               without the appropriate privilege. This error also occurs if
               attempting to install a database without the necessary operating
               system privileges.
               When Trusted Oracle is configure in DBMS MAC, this error may occur
               if the user was granted the necessary privilege at a higher label
               than the current login.
    *Action:   Ask the database administrator to perform the operation or grant
               the required privileges.
               For Trusted Oracle users getting this error although granted the
               the appropriate privilege at a higher label, ask the database
               administrator to regrant the privilege at the appropriate label. Vendor code 1031</p>
  </blockquote>