我的Like Query JDBC（Derby）有什么问题

Question

Until now, I'm confused when to double quote and single quote queries. My Search query doesn't seem to work. I'm trying to use % and surround the component Search_Textfield with % to get results but i think there's something wrong with my query. Here's my code.

private void Search_searchButtonActionPerformed(java.awt.event.ActionEvent evt) {                                                    
    try{
        String myUrl="jdbc:derby://localhost:1527/EMPLOYEEINFO";
        String username="ADMIN1";
        String password="ADMIN1";
        Connection myConnection = DriverManager.getConnection(myUrl, username, password);
        Statement myStatement = myConnection.createStatement();

        String myQuery = "SELECT * FROM EMPLOYEE WHERE EMPLOYEE_ID LIKE '%' '"+Search_TxtField.getText()+"' '%' ";

        ResultSet myRs = myStatement.executeQuery(myQuery);
        DefaultListModel myDLM = new DefaultListModel();

        while(myRs.next()){
          myDLM.addElement(myRs.getString(1));
        }//end of while loop

        Search_List.setModel(myDLM);


    }//end of try
    catch(SQLException ex){
        JOptionPane.showMessageDialog(null, ex.toString());
    }//end of catch
}           

Thanks.

Answer 1

The problem is with your single quotes. Instead of using

String myQuery = "SELECT * FROM EMPLOYEE WHERE EMPLOYEE_ID LIKE '%' '"+Search_TxtField.getText()+"' '%' ";

Try using:

String myQuery = "SELECT * FROM EMPLOYEE WHERE EMPLOYEE_ID LIKE '% "+Search_TxtField.getText()+" %' ";

The single quotes must include the % , so you search like '%testString%'

Answer 2

Did You try declare myQuery like:

String myQuery = "SELECT * FROM EMPLOYEE WHERE EMPLOYEE_ID LIKE '%"+Search_TxtField.getText()+"%' ";

or instead of like just equal '='

String myQuery = "SELECT * FROM EMPLOYEE WHERE EMPLOYEE_ID='"+Search_TxtField.getText()'";