CODEWITHSUNDEEP
javamysqlmethods
mhamad arsalan
mhamad arsalan

Reputation: 87

java - How to get max ID in SQL

It Takes Too Long For Me To Create And Send PreparedStatement's or ResultSet.

How Can I Get MaxID From SQL in Java Method?

Writed this but not working...

private static int getLastId()
{   
    int returned=0;

    try
    {
        PreparedStatement stat;
        ResultSet rs;
        String sql="select max(id) from home";
        stat=conn.prepareStatement(sql);
        rs=stat.executeQuery();
        while(rs.next())
        {
            returned = rs.getInt("id")+1;// just want a new id for new person
        }
    }
    catch (Exception e)
    {
        System.out.println(""+e);
    }
    return returned;
}

I Tried To Use It Like This...

                //reseting every thing and get lastId+1;
                System.out.println("added");
                field_name.setText("");
                field_pass.setText("");
                int temp= getLastId();
                field_id.setText(""+temp);

But It Returns 0! I Don't Have any SQL error.

Did I Use It Wrong? or ?

Thanks For Help.

Upvotes: 0

Views: 3509

Answers (1)

Tim Biegeleisen
Tim Biegeleisen

Reputation: 520978

You have a few problems here, one of which is that in your current code you aren't actually accessing the max(id) which you put in the query. One way around this is to assign an alias:

PreparedStatement stat;
ResultSet rs;
String sql = "SELECT MAX(id) AS max_id FROM home";
stat = conn.prepareStatement(sql);
rs = stat.executeQuery();
if (rs.next()) {
    returned = rs.getInt("max_id") + 1;
}

This fixes the syntax problem, but there is still the problem of whether this is the best way to get the next id. I would recommend that you switch to using an auto increment column, which MySQL will manage for you. Then, you don't need to worry about keeping track of the latest ID value. In fact, you don't even need to specify a value when inserting; the database will handle this for you.

Upvotes: 1

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