SQL-Java-UPDATE语句查询

Question

So what I want to do is "Update the 'usertype' column in the 'user' table WHERE the email(/user) value is obtained from the textbox"

JButton GrantButton = new JButton("Grant Seller Access");
GrantButton.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent arg0) {
        try {
            String update_query = "UPDATE user SET usertype = 'seller' WHERE email = " & GrantField.getText()";"
            //Here is where the error is stated on eclipse

            PreparedStatement pSt = connect.prepareStatement(update_query);
            pSt.setString(1, GrantField.getText());

            pSt.execute();

            JOptionPane.showMessageDialog(null, "The Request has been approved");

        } catch (Exception e) {                            
            e.printStackTrace();
        }           
    }
});  

Is it possible to do this?

Any help will be appreciated.

Answer 1

Your update_query is not proper. You are using setString on PreparedStatement but you are not specifying where this value should be inserted in query (you query is not parameterized). To specify that you need to write ? where you want to insert value. Also user is reserved word in database so ideally you should not use this name. For example :

String update_query = "UPDATE [table_name] SET usertype = seller WHERE email = ?" ;
PreparedStatement preparedStatement = dbConnection.prepareStatement(update_query);
preparedStatement.setString(1,Value);// this value will be replaced at ?

If you don't know how to connect to database from Java and create connection, you need to learn it from : http://docs.oracle.com/javase/tutorial/jdbc/

Answer 2

try wrapping your textbox value with single quotes like this:

String update_query = "UPDATE user 
                       SET usertype = 'seller' 
                       WHERE email = '" &  GrantField.getText() & "';"

I added an ampersand after getText() too.

Answer 3

There are some problem with your sql query.

1. The table name is User it is a reserve word so enclose it in ""
2. you are checking an email. It is varchar so it should enclose in '
3. Always try to use parameterized sql queries it would avoid sql injection problem

4. You are doing setstring to pass a value to the query but in the query you are not specifying where the value should be substituted.

   String update_query ="UPDATE "user" SET usertype = 'seller' WHERE email = '" & GrantField.getText()&"';" PreparedStatement pSt = connect.prepareStatement(update_query); //pSt.setString(1, GrantField.getText()); this statement not needed because you are providing the value in query iteself pSt.execute();

OR

String update_query = "UPDATE [user] SET usertype = 'seller' WHERE email = ?" ;
PreparedStatement pSt = dbConnection.prepareStatement(update_query);
pSt.setString(1,GrantField.getText());
pSt.execute();

Answer 4

Just modify this part

String update_query = "UPDATE user SET usertype = 'seller' WHERE ***email = '" + GrantField.getText()+"';***

hope it may work for you.