• select x, s from t: Execute the query using PQexec.

  • PQntuples(res): The number of rows (tuples) returned.

  • PQnfields(res): The number of columns in the result.

  • PQgetisnull(res, r, c): Is column c of row r NULL? Should always check for NULL before obtaining column value if there is any chance that the result could be NULL.

  • PQgetvalue(res, r, c): Get the value of column c of row r, as text.