Where Clause in MySQL - JAVA

Question

I'm newbie with mysql and this is my issue. I have a table in database called Room with one of its attribute as Floor. In the Floor column, there are 3 different names ( Walters, Gates, Pension).

I'm trying to fetch figures from table based on the selected floor and this is my query.

 String query = "Select * from Rooms where Floor =" + Floor.getSelectedItem().toString();

This seems like the right query but i get an error thrown saying Unknown Column 'Walters' in where clause.

What am i not doing right?

You should be using a prepared statement with a parameter placeholder. Please look at this tutorial: docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html — Mark Rotteveel
– Mark Rotteveel, Commented Sep 10, 2017 at 8:02
You're not using prepared statements to pass parameters, and thus avoid the need to properly escape parameters. docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html — JB Nizet
– JB Nizet, Commented Sep 10, 2017 at 8:02

Youcef LAIDANI · Accepted Answer · 2017-09-10 08:03:55Z

4

Your query is not correct, because String should be between to quotes "" :

String query = 
     "Select * from Rooms where Floor = '" + Floor.getSelectedItem().toString() + "'";
    //----------------------------------^------------------------------------------^

But this not secure, instead read about Prepared Statement to avoid SQL Injection and syntax error :

String query = "Select * from Rooms where Floor = ?";
PreparedStatement pstmt = con.prepareStatement(query);
pstmt.setString(1, Floor.getSelectedItem().toString());
pstmt.executeQuery();//then execute the statement

answered Sep 10, 2017 at 8:03

Youcef LAIDANI

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Comments

Drunken Daddy · Accepted Answer · 2017-09-10 08:02:44Z

1

strings in a query should be in single quotes, your query should be:

Select * from Rooms where Floor = 'Walter';

so your code should be:

String query = "Select * from Rooms where Floor = '" + Floor.getSelectedItem().toString() + "'";

It is better to use PreparedStatements to avoid confusion

answered Sep 10, 2017 at 8:02

Drunken Daddy

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Comments

Sanjay Kumaar · Accepted Answer · 2017-09-10 08:28:48Z

0

Use this,

String query = "Select * from Rooms where Floor ='" + Floor.getSelectedItem().toString();+"'"

answered Sep 10, 2017 at 8:28

Sanjay Kumaar

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