Java Postgresql How to generate primary key automatically

Question

I woudlike to generate automatically a new id (primary key) when I use INSERT INTO :

    String id = "1";
    PreparedStatement prep = conn.prepareStatement("INSERT INTO TABLE (id) VALUES(?)");
    prep.setString(1, id); // generate new id 
    prep.executeUpdate();

Actually I set 1 to my id but if I want to generate more INSERT INTO How can I INSERT INTO new value with new id ?

Does this answer your question? PostgreSQL Autoincrement Or this? Generate Auto ID in PostgreSQL — Nowhere Man
– Nowhere Man, Commented Oct 8, 2020 at 17:56
Related: How to get the insert ID in JDBC? If you want to generate an id, you shouldn't specify it in the query. — Mark Rotteveel
– Mark Rotteveel, Commented Oct 10, 2020 at 13:59

score 2 · Accepted Answer · 2020-10-08 19:11:40Z

2

Use an identity column:

create table foo 
(
  id integer primary key generated always as identity, 
  some_column text, 
  ... 
)

Then use PreparedStatement.getGeneratedKeys()

int id = -1;
PreparedStatement prep = conn.prepareStatement("INSERT INTO TABLE (some_column) VALUES(?)", Statement.RETURN_GENERATED_KEYS);
prep.setString(1, "some value");
prep.executeUpdate();
ResultSet rs = prep.getGeneratedKeys();
if (rs.next()) {
  id = rs.getInt(1);
}

edited Oct 8, 2020 at 19:11

answered Oct 8, 2020 at 17:56

user330315

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1 Comment

martin7887 Over a year ago

perfect ! Thank you ! (you just forget ')' after rs.next())

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