How to get a value from the last inserted row?

With PostgreSQL you can do it via the RETURNING keyword:

PostgresSQL - RETURNING

INSERT INTO mytable( field_1, field_2,... )
VALUES ( value_1, value_2 ) RETURNING anyfield

It will return the value of "anyfield". "anyfield" may be a sequence or not.

To use it with JDBC, do:

ResultSet rs = statement.executeQuery("INSERT ... RETURNING ID");
rs.next();
rs.getInt(1);

See the API docs for java.sql.Statement.

Basically, when you call executeUpdate() or executeQuery(), use the Statement.RETURN_GENERATED_KEYS constant. You can then call getGeneratedKeys to get the auto-generated keys of all rows created by that execution. (Assuming your JDBC driver provides it.)

It goes something along the lines of this:

Statement stmt = conn.createStatement();
stmt.execute(sql, Statement.RETURN_GENERATED_KEYS);
ResultSet keyset = stmt.getGeneratedKeys();

If you're using JDBC 3.0, then you can get the value of the PK as soon as you inserted it.

Here's an article that talks about how : https://www.ibm.com/developerworks/java/library/j-jdbcnew/

Statement stmt = conn.createStatement();
// Obtain the generated key that results from the query.
stmt.executeUpdate("INSERT INTO authors " +
                   "(first_name, last_name) " +
                   "VALUES ('George', 'Orwell')",
                   Statement.RETURN_GENERATED_KEYS);
ResultSet rs = stmt.getGeneratedKeys();
if ( rs.next() ) {
    // Retrieve the auto generated key(s).
    int key = rs.getInt(1);
}

The sequences in postgresql are transaction safe. So you can use the

currval(sequence)

Quote:

currval

Return the value most recently obtained by nextval for this sequence in the current session. (An error is reported if nextval has never been called for this sequence in this session.) Notice that because this is returning a session-local value, it gives a predictable answer even if other sessions are executing nextval meanwhile.

Here is how I solved it, based on the answers here:

Connection conn = ConnectToDB(); //ConnectToDB establishes a connection to the database.
String sql = "INSERT INTO \"TableName\"" +
        "(\"Column1\", \"Column2\",\"Column3\",\"Column4\")" +
        "VALUES ('value1',value2, 'value3', 'value4') RETURNING 
         \"TableName\".\"TableId\"";
PreparedStatement prpState = conn.prepareStatement(sql);
ResultSet rs = prpState.executeQuery();
if(rs.next()){
      System.out.println(rs.getInt(1));
        }

Use sequences in postgres for id columns:

INSERT mytable(myid) VALUES (nextval('MySequence'));

SELECT currval('MySequence');

currval will return the current value of the sequence in the same session.

(In MS SQL, you would use @@identity or SCOPE_IDENTITY())

PreparedStatement stmt = getConnection(PROJECTDB + 2)
    .prepareStatement("INSERT INTO fonts (font_size) VALUES(?) RETURNING fonts.*");
stmt.setString(1, "986");
ResultSet res = stmt.executeQuery();
while (res.next()) {
    System.out.println("Generated key: " + res.getLong(1));
    System.out.println("Generated key: " + res.getInt(2));
    System.out.println("Generated key: " + res.getInt(3));
}
stmt.close();