id|idterreno|idincorporadora|idusuario|msg|data
1 |    1    |      771      |   771   | a |2018-05-27 10:20:00
2 |    1    |      771      |   773   | b |2018-05-27 10:30:00
3 |    1    |      771      |   771   | c |2018-05-27 11:20:00
4 |    1    |      771      |   773   | d |2018-05-27 11:35:00
5 |    2    |      772      |   775   | e |2018-05-27 13:25:00

id|idterreno|idincorporadora|idusuario|msg|data
4 |    1    |      771      |   773   | d |2018-05-27 10:20:00
5 |    2    |      772      |   775   | e |2018-05-27 10:30:00

SELECT idterreno, idusuario, max(data)
FROM sir_ter_conversa
GROUP BY idterreno