r8873: better generic function

[clsql.git] / db-oracle / oracle-sql.lisp

;;; -*- Mode: Lisp -*-
;;; $Id$

;;; MaiSQL --- Common Lisp Interface Layer to SQL Databases
;;; This is copyrighted software.  See documentation for terms.
;;; 
;;; oracle-sql.lisp --- SQL-Interface implementation for Oracle
;;;
;;; derived from postgresql.lisp

(in-package :clsql-oracle)

(defmethod database-initialize-database-type
    ((database-type (eql :oracle)))
  t)

;;;; KLUDGE: The original prototype of this code was implemented using
;;;; lots of special variables holding MAKE-ALIEN values. When I was 
;;;; first converting it to use WITH-ALIEN variables, I was confused
;;;; about the behavior of MAKE-ALIEN and WITH-ALIEN; I thought that
;;;; (MAKE-ALIEN TYPEFOO) returned the same type of object as is bound
;;;; to the name BAR by (WITH-ALIEN ((BAR TYPEFOO)) ..). In fact the
;;;; value returned by MAKE-ALIEN has an extra level of indirection
;;;; relative to the value bound by WITH-ALIEN, i.e.  (DEREF
;;;; (MAKE-ALIEN TYPEFOO)) has the same type as the value bound to the
;;;; name BAR by (WITH-ALIEN ((BAR TYPEFOO)) ..). Laboring under my
;;;; misunderstanding, I was unable to use ordinary scalars bound by
;;;; WITH-ALIEN, and I ended up giving up and deciding to work around
;;;; this apparent bug in CMUCL by using 1-element arrays instead.
;;;; This "workaround" for my misunderstanding is obviously unnecessary
;;;; and confusing, but still remains in the code. -- WHN 20000106


;;;; arbitrary parameters, tunable for performance or other reasons

;;; the number of table rows that we buffer at once when reading a table
;;;
;;; CMUCL has a compiled-in limit on how much C data can be allocated
;;; (through malloc() and friends) at any given time, typically 8 Mb.
;;; Setting this constant to a moderate value should make it less
;;; likely that we'll have to worry about the CMUCL limit.
(defconstant +n-buf-rows+ 200)
;;; the number of characters that we allocate for an error message buffer
(defconstant +errbuf-len+ 512)

;;; utilities for mucking around with C-level stuff

;; Return the address of ALIEN-OBJECT (like the C operator "&").
;;
;; The INDICES argument is useful to give the ALIEN-OBJECT the
;; expected number of zero indices, especially when we have a bunch of
;; 1-element arrays running around due to the workaround for the CMUCL
;; 18b WITH-ALIEN scalar bug.

(defmacro c-& (alien-object &rest indices)
  `(addr (deref ,alien-object ,@indices)))

;; constants - from OCI?

(defconstant +var-not-in-list+       1007)
(defconstant +no-data-found+         1403)
(defconstant +null-value-returned+   1405)
(defconstant +field-truncated+       1406)

(defconstant SQLT-INT 3)
(defconstant SQLT-STR 5)
(defconstant SQLT-FLT 4)
(defconstant SQLT-DATE 12)

;;; Note that despite the suggestive class name (and the way that the
;;; *DEFAULT-DATABASE* variable holds an object of this class), a DB
;;; object is not actually a database but is instead a connection to a
;;; database. Thus, there's no obstacle to having any number of DB
;;; objects referring to the same database.

(defclass oracle-database (database)    ; was struct db
  ((envhp
    :reader envhp
    :initarg :envhp
    :type (alien (* (* t)))
    :documentation
    "OCI environment handle")
   (errhp
    :reader errhp
    :initarg :errhp
    :type (alien (* (* t)))
    :documentation
    "OCI error handle")
   (svchp
    :reader svchp
    :initarg :svchp
    :type (alien (* (* t)))
    :documentation
    "OCI service context handle")
   (data-source-name
    :initarg :dsn
    :initform nil
    :documentation
    "optional data source name (used only for debugging/printing)")
   (user
    :initarg :user
    :reader user
    :type string
    :documentation
    "the \"user\" value given when data source connection was made")
   (date-format
    :initarg :date-format
    :reader date-format
    :initform "YYYY-MM-DD HH24:MI:SS\"+00\"")
   (date-format-length
    :type number
    :documentation
    "Each database connection can be configured with its own date
output format.  In order to extract date strings from output buffers
holding multiple date strings in fixed-width fields, we need to know
the length of that format.")))


;;; Handle the messy case of return code=+oci-error+, querying the
;;; system for subcodes and reporting them as appropriate. ERRHP and
;;; NULLS-OK are as in the OERR function.

(defun handle-oci-error (&key database nulls-ok)
  (cond (database
         (with-slots (errhp)
           database
           (with-alien ((errbuf (array char #.+errbuf-len+))
                        (errcode (array long 1)))
             (setf (deref errbuf 0) 0) ; i.e. init to empty string
             (setf (deref errcode 0) 0)
             (oci-error-get (deref errhp) 1 "" (c-& errcode 0) (c-& errbuf 0) +errbuf-len+ +oci-htype-error+)
             (let ((subcode (deref errcode 0)))
               (unless (and nulls-ok (= subcode +null-value-returned+))
                 (error 'clsql-sql-error
                        :database database
                        :errno subcode
                        :error (cast (c-& errbuf 0) c-string)))))))
        (nulls-ok
         (error 'clsql-sql-error
                :database database
                :error "can't handle NULLS-OK without ERRHP"))
        (t 
         (error 'clsql-sql-error
                :database database
                :error "OCI Error (and no ERRHP available to find subcode)"))))

;;; Require an OCI success code.
;;;
;;; (The ordinary OCI error reporting mechanisms uses a fair amount of
;;; machinery (environments and other handles). In order to get to
;;; where we can use these mechanisms, we have to be able to allocate
;;; the machinery. The functions for allocating the machinery can
;;; return errors (e.g. out of memory) but shouldn't. Wrapping this function
;;; around function calls to such have-to-succeed functions enforces
;;; this condition.)

(defun osucc (code)
  (declare (type fixnum code))
  (unless (= code +oci-success+)
    (error 'dbi-error
           :format-control "unexpected OCI failure, code=~S"
           :format-arguments (list code))))


;;; Enabling this can be handy for low-level debugging.
#+nil
(progn
  (trace oci-initialize #+oci-8-1-5 oci-env-create oci-handle-alloc oci-logon
         oci-error-get oci-stmt-prepare oci-stmt-execute
         oci-param-get oci-logon oci-attr-get oci-define-by-pos oci-stmt-fetch)
  (setf debug::*debug-print-length* nil))


;;;; the OCI library, part V: converting from OCI representations to Lisp
;;;; representations

;; Return the INDEXth string of the OCI array, represented as Lisp
;; SIMPLE-STRING. SIZE is the size of the fixed-width fields used by
;; Oracle to store strings within the array.

;; In the wild world of databases, trailing spaces aren't generally
;; significant, since e.g. "LARRY " and "LARRY    " are the same string
;; stored in different fixed-width fields. OCI drops trailing spaces
;; for us in some cases but apparently not for fields of fixed
;; character width, e.g.
;;
;;   (dbi:sql "create table employees (name char(15), job char(15), city
;;            char(15), rate float)" :db orcl :types :auto)
;; In order to map the "same string" property above onto Lisp equality,
;; we drop trailing spaces in all cases:

(defun deref-oci-string (arrayptr string-index size)
  (declare (type (alien (* char)) arrayptr))
  (declare (type (mod #.+n-buf-rows+) string-index))
  (declare (type (and unsigned-byte fixnum) size))
  (let* ((raw (cast (addr (deref arrayptr (* string-index size))) c-string))
         (trimmed (string-trim " " raw)))
    (if (equal trimmed "NULL") nil trimmed)))

;; the OCI library, part Z: no-longer used logic to convert from
;; Oracle's binary date representation to Common Lisp's native date
;; representation

#+nil
(defvar +oci-date-bytes+ 7)

;;; Return the INDEXth date in the OCI array, represented as
;;; a Common Lisp "universal time" (i.e. seconds since 1900).

#+nil
(defun deref-oci-date (arrayptr index)
  (oci-date->universal-time (addr (deref arrayptr
                                         (* index +oci-date-bytes+)))))
#+nil
(defun oci-date->universal-time (oci-date)
  (declare (type (alien (* char)) oci-date))
  (flet (;; a character from OCI-DATE, interpreted as an unsigned byte
         (ub (i)
           (declare (type (mod #.+oci-date-bytes+) i))
           (mod (deref oci-date i) 256)))
    (let* ((century (* (- (ub 0) 100) 100))
           (year    (+ century (- (ub 1) 100)))
           (month   (ub 2))
           (day     (ub 3))
           (hour    (1- (ub 4)))
           (minute  (1- (ub 5)))
           (second  (1- (ub 6))))
      (encode-universal-time second minute hour day month year))))

;; Return (VALUES ALL-TABLES COLUMN-NAMES), where ALL-TABLES is a
;; table containing one row for each table available in DB, and
;; COLUMN-NAMES is a list of header names for the columns in
;; ALL-TABLES.
;;
;; The Allegro version also accepted a HSTMT argument.

;(defmethod database-list-tables ((db oracle-database))
;  (sql:query "select '',OWNER,TABLE_NAME,TABLE_TYPE,'' from all_catalog"))
  

(defmethod list-all-user-database-tables ((db oracle-database))
  (unless db
    (setf db sql:*default-database*))
  (values (database-query "select TABLE_NAME from all_catalog
                where owner <> 'PUBLIC' and owner <> 'SYSTEM' and owner <> 'SYS'"
                          db)))


(defmethod database-list-tables ((database oracle-database)
                                 &key (system-tables nil))
  (if system-tables
      (select [table_name] :from [all_catalog])
      (select [table_name] :from [all_catalog]
              :where [and [<> [owner] "PUBLIC"]
                          [<> [owner] "SYSTEM"]
                          [<> [owner] "SYS"]]
              :flatp t)))

;; Return a list of all columns in TABLE.
;;
;; The Allegro version of this also returned a second value.

(defmethod list-all-table-columns (table (db oracle-database))
  (declare (type string table))
  (unless db
    (setf db (default-database)))
  (let* ((sql-stmt (concatenate
                    'simple-string
                    "select "
                    "'',"
                    "all_tables.OWNER,"
                    "'',"
                    "user_tab_columns.COLUMN_NAME,"
                    "user_tab_columns.DATA_TYPE from user_tab_columns,"
                    "all_tables where all_tables.table_name = '" table "'"
                    " and user_tab_columns.table_name = '" table "'"))
         (preresult (sql sql-stmt :db db :types :auto)))
    ;; PRERESULT is like RESULT except that it has a name instead of
    ;; type codes in the fifth column of each row. To fix this, we
    ;; destructively modify PRERESULT.
    (dolist (preresult-row preresult)
      (setf (fifth preresult-row)
            (if (find (fifth preresult-row)
                      #("NUMBER" "DATE")
                      :test #'string=)
                2 ; numeric
                1))) ; string
    preresult))

(defmethod database-list-attributes (table (database oracle-database))
  (let* ((relname (etypecase table
                    (sql-sys::sql-ident
                     (string-upcase
                      (symbol-name (slot-value table 'sql-sys::name))))
                    (string table))))
    (select [user_tab_columns column_name]
            :from [user_tab_columns]
            :where [= [user_tab_columns table_name] relname]
            :flatp t)))



;; Return one row of the table referred to by QC, represented as a
;; list; or if there are no more rows, signal an error if EOF-ERRORP,
;; or return EOF-VALUE otherwise.

;; KLUDGE: This CASE statement is a strong sign that the code would be
;; cleaner if CD were made into an abstract class, we made variant
;; classes for CD-for-column-of-strings, CD-for-column-of-floats,
;; etc., and defined virtual functions to handle operations like
;; get-an-element-from-column. (For a small special purpose module
;; like this, would arguably be overkill, so I'm not going to do it
;; now, but if this code ends up getting more complicated in
;; maintenance, it would become a really good idea.)

;; Arguably this would be a good place to signal END-OF-FILE, but
;; since the ANSI spec specifically says that END-OF-FILE means a
;; STREAM which has no more data, and QC is not a STREAM, we signal
;; DBI-ERROR instead.

(defun fetch-row (qc &optional (eof-errorp t) eof-value)
  (declare (optimize (speed 3)))
  (cond ((zerop (qc-n-from-oci qc))
         (if eof-errorp
             (dbi-error "no more rows available in ~S" qc)
           eof-value))
        ((>= (qc-n-to-dbi qc)
             (qc-n-from-oci qc))
         (refill-qc-buffers qc)
         (fetch-row qc nil eof-value))
        (t
         (let ((cds (qc-cds qc))
               (reversed-result nil)
               (irow (qc-n-to-dbi qc)))
           (dotimes (icd (length cds))
             (let* ((cd (aref cds icd))
                    (b (alien-resource-buffer (cd-buffer cd)))
                    (value
                     (let ((arb (alien-resource-buffer (cd-indicators cd))))
                       (declare (type (alien (* (alien:signed 16))) arb))
                       (unless (= (deref arb irow) -1)
                         (ecase (cd-oci-data-type cd)
                           (#.SQLT-STR  (deref-oci-string b irow (cd-sizeof cd)))
                           (#.SQLT-FLT  (deref (the (alien (* double)) b) irow))
                           (#.SQLT-INT  (deref (the (alien (* int)) b) irow))
                           (#.SQLT-DATE (deref-oci-string b irow (cd-sizeof cd))))))))
               (push value reversed-result)))
           (incf (qc-n-to-dbi qc))
           (nreverse reversed-result)))))

(defun refill-qc-buffers (qc)
  (with-slots (errhp)
    (qc-db qc)
    (setf (qc-n-to-dbi qc) 0)
    (cond ((qc-oci-end-seen-p qc)
           (setf (qc-n-from-oci qc) 0))
          (t
           (let ((oci-code (%oci-stmt-fetch (deref (qc-stmthp qc))
                                           (deref errhp)
                                           +n-buf-rows+
                                           +oci-fetch-next+ +oci-default+)))
             (ecase oci-code
               (#.+oci-success+ (values))
               (#.+oci-no-data+ (setf (qc-oci-end-seen-p qc) t)
                                (values))
               (#.+oci-error+ (handle-oci-error :database (qc-db qc)
                                                :nulls-ok t))))
           (with-alien ((rowcount (array unsigned-long 1)))
             (oci-attr-get (deref (qc-stmthp qc)) +oci-htype-stmt+
                           (c-& rowcount 0) nil +oci-attr-row-count+ 
                           (deref errhp))
             (setf (qc-n-from-oci qc)
                   (- (deref rowcount 0) (qc-total-n-from-oci qc)))
             (when (< (qc-n-from-oci qc) +n-buf-rows+)
               (setf (qc-oci-end-seen-p qc) t))
             (setf (qc-total-n-from-oci qc)
                   (deref rowcount 0)))))
    (values)))

;; the guts of the SQL function
;;
;; (like the SQL function, but with the QUERY argument hardwired to T, so
;; that the return value is always a cursor instead of a list)

;; Is this a SELECT statement?  SELECT statements are handled
;; specially by OCIStmtExecute().  (Non-SELECT statements absolutely
;; require a nonzero iteration count, while the ordinary choice for a
;; SELECT statement is a zero iteration count.

;; SELECT statements are the only statements which return tables.  We
;; don't free STMTHP in this case, but instead give it to the new
;; QUERY-CURSOR, and the new QUERY-CURSOR becomes responsible for
;; freeing the STMTHP when it is no longer needed.

(defun sql-stmt-exec (sql-stmt-string db &key types)
  (with-slots (envhp svchp errhp)
    db
    (let ((stmthp (make-alien (* t))))
      (with-alien ((stmttype (array unsigned-short 1)))
        
        (oci-handle-alloc (deref envhp) (c-& stmthp) +oci-htype-stmt+ 0 nil)
        (oci-stmt-prepare (deref stmthp) (deref errhp)
                          sql-stmt-string (length sql-stmt-string)
                          +oci-ntv-syntax+ +oci-default+ :database db)
        (oci-attr-get (deref stmthp) +oci-htype-stmt+ 
                      (c-& stmttype 0) nil +oci-attr-stmt-type+ 
                      (deref errhp) :database db)
        (let* ((select-p (= (deref stmttype 0) 1)) 
               (iters (if select-p 0 1)))
          
          (oci-stmt-execute (deref svchp) (deref stmthp) (deref errhp)
                            iters 0 nil nil +oci-default+ :database db)
          (cond (select-p
                 (make-query-cursor db stmthp types))
                (t
                 (oci-handle-free (deref stmthp) +oci-htype-stmt+)
                 nil)))))))


;; Return a QUERY-CURSOR representing the table returned from the OCI
;; operation done through STMTHP.  TYPES is the argument of the same
;; name from the external SQL function, controlling type conversion
;; of the returned arguments.

(defun make-query-cursor (db stmthp types)
  (let ((qc (%make-query-cursor :db db
                                :stmthp stmthp
                                :cds (make-query-cursor-cds db stmthp types))))
    (refill-qc-buffers qc)
    qc))


;; the hairy part of MAKE-QUERY-CURSOR: Ask OCI for information
;; about table columns, translate the information into a Lisp
;; vector of column descriptors, and return it.

;; Allegro defines several flavors of type conversion, but this
;; implementation only supports the :AUTO flavor.

;; A note of explanation: OCI's internal number format uses 21
;; bytes (42 decimal digits). 2 separate (?) one-byte fields,
;; scale and precision, are used to deduce the nature of these
;; 21 bytes. See pp. 3-10, 3-26, and 6-13 of OCI documentation
;; for more details.

;; When calling OCI C code to handle the conversion, we have
;; only two numeric types available to pass the return value:
;; double-float and signed-long. It would be possible to
;; bypass the OCI conversion functions and write Lisp code
;; which reads the 21-byte field directly and decodes
;; it. However this is left as an exercise for the reader. :-)

;; The following table describes the mapping, based on the implicit
;; assumption that C's "signed long" type is a 32-bit integer.
;;
;;   Internal Values                     SQL Type        C Return Type
;;   ===============                     ========        =============
;;   Precision > 0        SCALE = -127   FLOAT       --> double-float
;;   Precision > 0 && <=9 SCALE = 0      INTEGER     --> signed-long
;;   Precision = 0 || > 9 SCALE = 0      BIG INTEGER --> double-float
;;   Precision > 0        SCALE > 0      DECIMAL     --> double-float

;; (OCI uses 1-based indexing here.)

;; KLUDGE: This should work for all other data types except those
;; which don't actually fit in their fixed-width field (BLOBs and the
;; like). As Winton says, we (Cadabra) don't need to worry much about
;; those, since we can't reason with them, so we don't use them. But
;; for a more general application it'd be good to have a more
;; selective and rigorously correct test here for whether we can
;; actually handle the given DEREF-DTYPE value. -- WHN 20000106

;; Note: The OCI documentation doesn't seem to say whether the COLNAME
;; value returned here is a newly-allocated copy which we're
;; responsible for freeing, or a pointer into some system copy which
;; will be freed when the system itself is shut down.  But judging
;; from the way that the result is used in the cdemodsa.c example
;; program, it looks like the latter: we should make our own copy of
;; the value, but not try to free it.

;; WORKAROUND: OCI seems to return ub2 values for the
;; +oci-attr-data-size+ attribute even though its documentation claims
;; that it returns a ub4, and even though the associated "sizep" value
;; is 4, not 2.  In order to make the code here work reliably, without
;; having to patch it later if OCI is ever fixed to match its
;; documentation, we pre-zero COLSIZE before making the call into OCI.

;; To exercise the weird OCI behavior (thereby blowing up the code
;; below, beware!) try setting this value into COLSIZE, calling OCI,
;; then looking at the value in COLSIZE.  (setf colsize #x12345678)
;; debugging only
            

(defun make-query-cursor-cds (database stmthp types)
  (declare (optimize (speed 3))
           (type oracle-database database)
           (type (alien (* (* t))) stmthp))
  (with-slots (errhp)
    database
    (unless (eq types :auto)
      (error "unsupported TYPES value"))
    (with-alien ((dtype unsigned-short 1)
                 (parmdp (* t))
                 (precision (unsigned 8))
                 (scale (signed 8))
                 (colname c-string)
                 (colnamelen unsigned-long)
                 (colsize unsigned-long)
                 (colsizesize unsigned-long)
                 (defnp (* t)))
      (let ((buffer nil)
            (sizeof nil))
        (do ((icolumn 0 (1+ icolumn))
             (cds-as-reversed-list nil))
            ((not (eql (oci-param-get (deref stmthp) +oci-htype-stmt+
                                      (deref errhp) (addr parmdp)
                                      (1+ icolumn) :database database)
                       +oci-success+))
             (coerce (reverse cds-as-reversed-list) 'simple-vector))
          ;; Decode type of ICOLUMNth column into a type we're prepared to
          ;; handle in Lisp.
          (oci-attr-get parmdp +oci-dtype-param+ (addr dtype)
                        nil +oci-attr-data-type+ (deref errhp))
          (case dtype
            (#.SQLT-DATE
             (setf buffer (acquire-alien-resource char (* 32 +n-buf-rows+)))
             (setf sizeof 32 dtype #.SQLT-STR))
            (2 ;; number
             ;;(oci-attr-get parmdp +oci-dtype-param+
             ;;(addr precision) nil +oci-attr-precision+
             ;;(deref errhp))
             (oci-attr-get parmdp +oci-dtype-param+
                           (addr scale) nil +oci-attr-scale+
                           (deref errhp))
             (cond
              ((zerop scale)
               (setf buffer (acquire-alien-resource signed +n-buf-rows+)
                     sizeof 4                   ;; sizeof(int)
                     dtype #.SQLT-INT))
              (t
               (setf buffer (acquire-alien-resource double-float +n-buf-rows+)
                     sizeof 8                   ;; sizeof(double)
                     dtype #.SQLT-FLT))))          
            (t  ; Default to SQL-STR
             (setf colsize 0
                   dtype #.SQLT-STR)
             (oci-attr-get parmdp +oci-dtype-param+ (addr colsize)
                           (addr colsizesize) +oci-attr-data-size+
                           (deref errhp))
             (let ((colsize-including-null (1+ colsize)))
               (setf buffer (acquire-alien-resource char (* +n-buf-rows+ colsize-including-null)))
               (setf sizeof colsize-including-null))))
          (let ((retcodes (acquire-alien-resource short +n-buf-rows+))
                (indicators (acquire-alien-resource short +n-buf-rows+)))
            (push (make-cd :name "col" ;(subseq colname 0 colnamelen)
                           :sizeof sizeof
                           :buffer buffer
                           :oci-data-type dtype
                           :retcodes retcodes
                           :indicators indicators)
                  cds-as-reversed-list)
            (oci-define-by-pos (deref stmthp)
                               (addr defnp)
                               (deref errhp)
                               (1+ icolumn) ; OCI 1-based indexing again
                               (alien-resource-buffer buffer)
                               sizeof
                               dtype
                               (alien-resource-buffer indicators)
                               nil
                               (alien-resource-buffer retcodes)
                               +oci-default+)))))))

;; Release the resources associated with a QUERY-CURSOR.

(defun close-query (qc)
  (oci-handle-free (deref (qc-stmthp qc)) +oci-htype-stmt+)
  (let ((cds (qc-cds qc)))
    (dotimes (i (length cds))
      (release-cd-resources (aref cds i))))
  (values))


;; Release the resources associated with a column description.

(defun release-cd-resources (cd)
  (free-alien-resource (cd-buffer cd))
  (free-alien-resource (cd-retcodes cd))
  (free-alien-resource (cd-indicators cd))
  (values))


(defmethod print-object ((db oracle-database) stream)
  (print-unreadable-object (db stream :type t :identity t)
    (format stream "\"/~a/~a\""
            (slot-value db 'data-source-name)
            (slot-value db 'user))))


(defmethod database-name-from-spec (connection-spec (database-type (eql :oracle)))
  (check-connection-spec connection-spec database-type (user password dsn))
  (destructuring-bind (user password dsn)
      connection-spec
    (declare (ignore password))
    (concatenate 'string "/" dsn "/" user)))


(defmethod database-connect (connection-spec (database-type (eql :oracle)))
  (check-connection-spec connection-spec database-type (user password dsn))
  (destructuring-bind (user password data-source-name)
      connection-spec
    (let ((envhp (make-alien (* t)))
          (errhp (make-alien (* t)))
          (svchp (make-alien (* t)))
          (srvhp (make-alien (* t))))
      ;; Requests to allocate environments and handles should never
      ;; fail in normal operation, and they're done too early to
      ;; handle errors very gracefully (since they're part of the
      ;; error-handling mechanism themselves) so we just assert they
      ;; work.
      (setf (deref envhp) nil)
      #+oci-8-1-5
      (progn
        (oci-env-create (c-& envhp) +oci-default+ nil nil nil nil 0 nil)
        (oci-handle-alloc (deref envhp) (c-& errhp) +oci-htype-error+ 0 nil))
      #-oci-8-1-5
      (progn
        (oci-initialize +oci-object+ nil nil nil nil)
        (ignore-errors (oci-handle-alloc nil (c-& envhp) +oci-htype-env+ 0 nil)) ;no testing return
        (oci-env-init (c-& envhp) +oci-default+ 0 nil)
        (oci-handle-alloc (deref envhp) (c-& errhp) +oci-htype-error+ 0 nil)
        (oci-handle-alloc (deref envhp) (c-& srvhp) +oci-htype-server+ 0 nil)
        ;;(osucc (oci-server-attach srvhp errhp nil 0 +oci-default+))
        (oci-handle-alloc (deref envhp) (c-& svchp) +oci-htype-svcctx+ 0 nil)
        ;; oci-handle-alloc((dvoid *)encvhp, (dvoid **)&stmthp, OCI_HTYPE_STMT, 0, 0);
        #+nil
        (oci-attr-set (deref svchp) +oci-htype-svcctx+ (deref srvhp) 0 +oci-attr-server+ errhp)
        )

      #+nil
      (format t "Logging in as user '~A' to database ~A~%"
              user password data-source-name)
      (oci-logon (deref envhp) (deref errhp) (c-& svchp)
                 user (length user)
                 password (length password)
                 data-source-name (length data-source-name))
      (let ((db (make-instance 'oracle-database
                               :name (database-name-from-spec connection-spec
                                                              database-type)
                               :envhp envhp
                               :errhp errhp
                               :db-type :oracle
                               :svchp svchp
                               :dsn data-source-name
                               :user user)))
        ;; :date-format-length (1+ (length date-format)))))
        (sql:execute-command
         (format nil "alter session set NLS_DATE_FORMAT='~A'"
                 (date-format db)) :database db)
        db))))


;; Close a database connection.

(defmethod database-disconnect ((database oracle-database))
  (osucc (oci-logoff (deref (svchp database)) (deref (errhp database))))
  (osucc (oci-handle-free (deref (envhp database)) +oci-htype-env+))
  ;; Note: It's neither required nor allowed to explicitly deallocate the
  ;; ERRHP handle here, since it's owned by the ENVHP deallocated above,
  ;; and was therefore automatically deallocated at the same time.
  t)

;;; Do the database operation described in SQL-STMT-STRING on database
;;; DB and, if the command is a SELECT, return a representation of the
;;; resulting table. The representation of the table is controlled by the
;;; QUERY argument:
;;;   * If QUERY is NIL, the table is returned as a list of rows, with
;;;     each row represented by a list.
;;;   * If QUERY is non-NIL, the result is returned as a QUERY-CURSOR
;;;     suitable for FETCH-ROW and CLOSE-QUERY
;;; The TYPES argument controls the type conversion method used
;;; to construct the table. The Allegro version supports several possible
;;; values for this argument, but we only support :AUTO.

(defmethod database-query (query-expression (database oracle-database))
  (let ((cursor (sql-stmt-exec query-expression database :types :auto)))
    (declare (type (or query-cursor null) cursor))
    (if (null cursor) ; No table was returned.
        (values)
      (do ((reversed-result nil))
          (nil)
        (let* ((eof-value :eof)
               (row (fetch-row cursor nil eof-value)))
          (when (eq row eof-value)
            (close-query cursor)
            (return (nreverse reversed-result)))
          (push row reversed-result))))))


(defmethod database-create-sequence
  (sequence-name (database oracle-database))
  (execute-command
   (concatenate 'string "CREATE SEQUENCE "
                (sql-escape sequence-name))
   :database database))

(defmethod database-drop-sequence
  (sequence-name (database oracle-database))
  (execute-command
   (concatenate 'string "DROP SEQUENCE "
                (sql-escape sequence-name))
   :database database))

(defmethod database-sequence-next (sequence-name (database oracle-database))
  (caar
   (query
    (concatenate 'string "SELECT "
                 (sql-escape sequence-name)
                 ".NEXTVAL FROM dual"
                 ) :database database)))


(defmethod database-execute-command
  (sql-expression (database oracle-database))
  (database-query sql-expression database)
  ;; HACK HACK HACK
  (database-query "commit" database)
  t)


;;; a column descriptor: metadata about the data in a table
(defstruct (cd (:constructor make-cd)
               (:print-function print-cd))
  ;; name of this column
  (name (error "missing NAME") :type simple-string :read-only t)
  ;; the size in bytes of a single element
  (sizeof (error "missing SIZE") :type fixnum :read-only t)
  ;; an array of +N-BUF-ROWS+ elements in C representation
  (buffer (error "Missing BUFFER")
          :type alien-resource
          :read-only t)
  ;; an array of +N-BUF-ROWS+ OCI return codes in C representation.
  ;; (There must be one return code for every element of every
  ;; row in order to be able to represent nullness.)
  (retcodes (error "Missing RETCODES")
            :type alien-resource
            :read-only t)
  (indicators (error "Missing INDICATORS")
              :type alien-resource
              :read-only t)
  ;; the OCI code for the data type of a single element
  (oci-data-type (error "missing OCI-DATA-TYPE")
                 :type fixnum
                 :read-only t))


(defun print-cd (cd stream depth)
  (declare (ignore depth))
  (print-unreadable-object (cd stream :type t)
    (format stream
            ":NAME ~S :OCI-DATA-TYPE ~S :OCI-DATA-SIZE ~S"
            (cd-name cd)
            (cd-oci-data-type cd)
            (cd-sizeof cd))))

;;; the result of a database query: a cursor through a table
(defstruct (oracle-result-set (:print-function print-query-cursor)
                              (:conc-name "QC-")
                              (:constructor %make-query-cursor))
  (db (error "missing DB")              ; db conn. this table is associated with
    :type db
    :read-only t)
  (stmthp (error "missing STMTHP")      ; the statement handle used to create
    :type alien                         ; this table. owned by the QUERY-CURSOR
    :read-only t)                       ; object, deallocated on CLOSE-QUERY
  (cds) ;  (error "missing CDS")            ; column descriptors
;    :type (simple-array cd 1)
;    :read-only t)
  (n-from-oci 0                         ; buffered rows: number of rows recv'd
    :type (integer 0 #.+n-buf-rows+))   ; from the database on the last read
  (n-to-dbi 0                           ; number of buffered rows returned, i.e.
    :type (integer 0 #.+n-buf-rows+))   ; the index, within the buffered rows,
                                        ; of the next row which hasn't already
                                        ; been returned
  (total-n-from-oci 0                   ; total number of bytes recv'd from OCI
    :type unsigned-byte)                ; in all reads
  (oci-end-seen-p nil))                 ; Have we seen the end of OCI
                                        ; data, i.e. OCI returning
                                        ; less data than we requested?
                                        ; OCI doesn't seem to like us
                                        ; to try to read more data
                                        ; from it after that..

(defun print-query-cursor (qc stream depth)
  (declare (ignore depth))
  (print-unreadable-object (qc stream :type t :identity t)
    (prin1 (qc-db qc) stream)))


(defmethod database-query-result-set ((query-expression string)
                                      (database oracle-database) 
                                      &key full-set types)
  )

(defmethod database-dump-result-set (result-set (database oracle-database))
  )

(defmethod database-store-next-row (result-set (database oracle-database) list)
  )

(defmethod sql-sys::database-start-transaction ((database oracle-database))
  (call-next-method))

;;(with-slots (svchp errhp) database
;;    (osucc (oci-trans-start (deref svchp)
;;                          (deref errhp)
;;                          60
;;                          +oci-trans-new+)))
;;  t)
  

(defmethod sql-sys::database-commit-transaction ((database oracle-database))
  (call-next-method)
  (with-slots (svchp errhp) database
              (osucc (oci-trans-commit (deref svchp)
                                       (deref errhp)
                                       0)))
  t)

(defmethod sql-sys::database-abort-transaction ((database oracle-database))
  (call-next-method)
  (osucc (oci-trans-rollback (deref (svchp database))
                           (deref (errhp database))
                           0))
  t)

(defparameter *constraint-types*
  '(("NOT-NULL" . "NOT NULL")))

(defmethod database-output-sql ((str string) (database oracle-database))
  (if (and (null (position #\' str))
           (null (position #\\ str)))
      (format nil "'~A'" str)
    (let* ((l (length str))
           (buf (make-string (+ l 3))))
      (setf (aref buf 0) #\')
      (do ((i 0 (incf i))
           (j 1 (incf j)))
          ((= i l) (setf (aref buf j) #\'))
        (if (= j (- (length buf) 1))
            (setf buf (adjust-array buf (+ (length buf) 1))))
        (cond ((eql (aref str i) #\')
               (setf (aref buf j) #\')
               (incf j)))
        (setf (aref buf j) (aref str i)))
      buf)))