java - Updating existing Row on database jdbc -

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No error is showing, when I click on the button, but the database is not updated on the table. 

  string heh = jlabel 17.getText (); Try {stmt.executeUpdate ("update books SET availability = '" + "missing" + "' where book_title = '" + heh + "' ');} hold (SQLException error) {System.out.println (err) .getMessage ());}

You completely messed up the query , 

  stmt.executeUpdate ("update books SET availability = '" + "missing" + "' where book_ title = '" + + + "' ');

may be, 

  stmt.executeUpdate ("Set availability of books SET availability = 'unavailable' Where book_title = '" + heh + " '');

You are advised to print the query before executing, because it avoids common mistakes, try to use the prepared statement as well, because your SQL is weak for injection

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