Question

I am using PostgreSQL 9.1.4 with hstore and the PostgreSQL JDBC driver (9.1-901.jdbc4).

I am trying to use the contains operators (?, ?&, ?|) in a PreparedStatement, however the ? character is parsed as a variable placeholder. Can this character be escaped to send the correct operator in the query?

An example:

PreparedStatement stmt = conn.prepareStatement("SELECT a, b FROM table1 WHERE c ? 'foo' AND d = ?");
stmt.setInt(1, dValue);
stmt.executeQuery();

In this form the following example would raise an exception:

org.postgresql.util.PSQLException: No value specified for parameter 2.

Update:

After investigating the query parser in the pgjdbc driver this snippet seems to indicate that it is not possible to escape the ? character. The questions that remain are:

• Is there anything in the JDBC spec which allows a ? to be escaped and be anything other than a parameter placeholder?
• Is there any better work around for this issue than just using plain Statements with variables manually inserted into the query string?

Answer 1

Effectively, it looks like the java SQL parser is not hstore compliant.

But since the syntax c ? 'foo' is equivalent to exist(c, 'foo'), you can easily workaround this problem. Have a look at the following page to see what the verbose operators for hstore are.

Postgres hstore documentation