Postgresql：null 及其附近的语法错误

Question

I have a web application that is connected to postgresql. I'm trying to get data from the database with a prepared statement and continuously get syntax error at or near null.

Following is my code snippet for query:

PreparedStatement pstmt = conn.prepareStatement("SELECT * "+ "FROM rooms1 o " + "JOIN rooms2 op" +
                                                 " ON o.room_id = op.room_id " +"JOIN rooms3 p " +
                                                 " ON op.person_id = p.person_id " +
                                                 "WHERE o.room_id = ? " +
                                                 " ORDER BY o.plate_order ASC;")) {
  //Rest of code

this query works fine when check on test database but when use it inside prepared statement it gives error as

Caused by: org.postgresql.util.PSQLException: ERROR: syntax error at or near "null"
position: 54

From some research I think that problem is with my query, also this is my first time writing Postgresql queries. please have look at it.

Answer 1

o.room_id =? if? is null so u have to check "o.room_id is null". u can check this with inline if

Answer 2

I have indicated the error position 54 with *** :

SELECT * FROM rooms1 o
JOIN rooms2 op ON o.room_id = ***op.room_id
JOIN rooms3 p  ON op.person_id = p.person_id
WHERE o.room_id = ?
ORDER BY o.plate_order ASC

I do not entirely understand the error message but op.room_id perhaps has null occurrences.

Weird error IMHO, but try a LEFT JOIN

SELECT o.*, op.*, p.* FROM rooms1 o
LEFT JOIN rooms2 op ON o.room_id = op.room_id
LEFT JOIN rooms3 p  ON op.person_id = p.person_id
WHERE o.room_id = ?
ORDER BY o.plate_order ASC

(The semicolon ; at the end is superfluous.)