;; Postgresql C library interface, example program 1, using the xedit
;; lisp interface
;; Test the C version of libpq, the PostgreSQL frontend library.
(require "psql")
(defun exit-nicely (conn)
(pq-finish conn)
(quit 1)
)
;; begin, by setting the parameters for a backend connection if the
;; parameters are null, then the system will try to use reasonable
;; defaults by looking up environment variables or, failing that,
;; using hardwired constants
(setq pghost nil) ; host name of the backend server
(setq pgport nil) ; port of the backend server
(setq pgoptions nil) ; special options to start up the backend server
(setq pgtty nil) ; debugging tty for the backend server
(setq pgdbname "template1")
;; make a connection to the database
(setq conn (pq-setdb pghost pgport pgoptions pgtty pgdbname))
;; check to see that the backend connection was successfully made
(when (= (pq-status conn) pg-connection-bad)
(format t "Connection to database '~A' failed.~%" pgdbname)
(format t "~A" (pq-error-message conn))
(exit-nicely conn))
;; start a transaction block
(setq res (pq-exec conn "BEGIN"))
(when (or (null res) (not (= (pq-result-status res) pgres-command-ok)))
(format t "BEGIN command failed~%")
(pq-clear res)
(exit-nicely conn))
;; Should PQclear PGresult whenever it is no longer needed to avoid memory leaks
(pq-clear res)
;; fetch rows from the pg_database, the system catalog of databases
(setq res (pq-exec conn "DECLARE mycursor CURSOR FOR select * from pg_database"))
(when (or (null res) (not (= (pq-result-status res) pgres-command-ok)))
(format t "DECLARE CURSOR command failed~%")
(pq-clear res)
(exit-nicely conn))
(pq-clear res)
(setq res (pq-exec conn "FETCH ALL in mycursor"))
(when (or (null res) (not (= (pq-result-status res) pgres-tuples-ok)))
(format t "FETCH ALL command didn't return tuples properly~%")
(pq-clear res)
(exit-nicely conn))
;; first, print out the attribute names
(setq nfields (pq-nfields res))
(dotimes (i nfields)
(format t "~15@<~A~>" (pq-fname res i))
)
(format t "~%")
;; next, print out the rows
(setq ntuples (pq-ntuples res))
(dotimes (i ntuples)
(dotimes (j nfields)
(format t "~15@<~A~>" (pq-getvalue res i j))
)
(format t "~%")
)
(pq-clear res)
;; close the cursor
(setq res (pq-exec conn "CLOSE mycursor"))
(pq-clear res)
;; commit the transaction
(setq res (pq-exec conn "COMMIT"))
(pq-clear res)
;; close the connection to the database and cleanup
(pq-finish conn)