Check if update query affected row or not

Question

If I want to select stuff in my database I can just executeQuery in a ResultSet and return that to see what I got. But how do I do checks if I want to insert or update rows?
How can I see what the db returned? If it affected anything?

public static boolean doUpdate(String statement) {
    openConnection();
    try {
        stmt = conn.createStatement();
        stmt.executeUpdate(statement);
        closeConnection();
        return true;
    } catch (SQLException ex) {
        System.out.println(DBhandler.class.getName()+"\n"+ex);
        closeConnection();
    }
    return false;
}

I have tried to give the function a boolean return value, but the code in try will continue no matter if the update/insert worked or not.

Doesn't [Statement.executeUpdate](http://docs.oracle.com/javase/8/docs/api/java/sql/Statement.html#executeUpdate-java.lang.String-) already return the number of affected rows by your update? — Edwin Dalorzo, Sep 25 '14 at 18:03

score 3 · Answer 1 · edited Jun 20 '20 at 09:12

3

The executeUpdate method returns the number of rows affected for appropriate SQL statements executed.

Returns:

either (1) the row count for SQL Data Manipulation Language (DML) statements or (2) 0 for SQL statements that return nothing

int rows = executeUpdate(statement);

Then you can look at rows to see if it's 0, and return a boolean appropriately.

edited Jun 20 '20 at 09:12

Community

1
1

answered Sep 25 '14 at 18:03

rgettman

167,281
27
248
326

I just tried this, even though the update query works, it returns 0 in my row variable?? – Mac Luc Sep 25 '14 at 20:05

score 2 · Accepted Answer · edited Oct 05 '17 at 19:38

2

The executeUpdate command returns the number of the affected rows. Keep that number and return true if at least one row was affected. Furthermore you should close your connection in a finally block, so even an exception occurs, the closeConnection() will be executed. Take a look at the below code.

public static boolean doUpdate(String statement) {
    boolean result = false;
    openConnection();
    try {
        stmt = conn.createStatement();
        result = stmt.executeUpdate(statement) > 0;
    } catch (SQLException ex) {
        System.out.println(DBhandler.class.getName()+"\n"+ex);
    } finally {
        closeConnection();
    }

    return result;
}

edited Oct 05 '17 at 19:38

Barzev

392
2
13

answered Sep 25 '14 at 18:11

Alkis Kalogeris

14,519
11
50
98

This will return false no matter what..? – Mac Luc Sep 25 '14 at 19:59
Aha! it was because you run executeUpdate twice in your example! works superb now :) thanks – Mac Luc Sep 25 '14 at 20:46
Oops, sorry about that. – Alkis Kalogeris Sep 25 '14 at 21:05

Check if update query affected row or not

2 Answers2