dbd-oracle: Oracle database driver for CL-DBI
This driver is based on OCI bindings developed for CLSQL.
This library provides Oracle interface to CL-DBI, so any CL-DBI-complaint program should work. Please, note the following limitations.
Connecting to ORACLE database
Connection can be estabslished by providing appropriate database name
dbi:connect method. The value of
database-name key argument is an
ORACLE connect string that might include hostname, listener port
number, and oracle SID or service name. For example,
(defvar *connection* (dbi:connect :oracle :database-name "127.0.0.1:1521/orcl" :username "nobody" :password "1234" :encoding :utf-8))
Encoding parameter is used for conversion of character strings between OCI library and Lisp. :utf-8 is the default encoding. Possible values for encoding parameter is the same as for CFFI string conversion functions. If :encoding keyword is not fiven, the library accesses NLS_LANG enironment variable. Note, that Oracle encoding names appearing in NLS_LANG may not match the names used in CFFI.
Loading OCI library
The application makes an attempt to load Oracle OCI library during the
first call to
dbi:connect. By default, the OCI library is searched in
ORACLE_HOME, ORACLE_HOME/lib, and ORACLE_HOME/bin directories, as well
as in the current directory. If ORACLE_HOME environment variable is
not set, then search paths can be provided by setting
dbd.oracle:*foreign-library-search-paths* variable. The value
assigned to this variable should be a list of pathnames. For example,
(let* ((dbd.oracle:*foreign-library-search-paths* '(#p"/opt/oracle/")) (connection (dbi:connect :oracle :database-name "localhost/orcl" :username "nobody" :password "1234"))) (dbi:disconect connection))
You may need to create a symbolic link for
libclntsh.so pointing to
an appropriate library, e.g.
Writing queries: space before question
Queries are evaluated using CL-DBI interface. Parameters bindings is
not guaranteed to work properly due to incompatible syntax for
placeholders definitions used in CL-DBI and Oracle queries. Oracle
requires parameter name to start with a colon, while CL-DBI uses the
? to define placeholders. Simple substitution of all
occurrences of " ?" (a space followed by a question mark) by
Oracle-friendly column expressions is performed for the entire SQL
(defvar *connection* (dbi:connect :mysql :database-name "test" :username "nobody" :password "1234")) (let* ((query (dbi:prepare *connection* "SELECT * FROM somewhere WHERE flag = ? OR updated_at > ?")) (result (dbi:execute query (list 0 "2011-11-01")))) (loop for row = (dbi:fetch result) while row ;; process "row". ))
The effectve query would be
"SELECT * FROM somewhere WHERE flag = :1 OR updated_at > :2".
If a question mark appears inside a quoted string of the SQL query,
then the effective query could not be identical to the original
one. The rule of thumb is to avoid using French punctuation style in
literal constants inside the main body of SQL queries (bound strings
are processed as is), and to put space before every placeholder. Automatic
substitution of question marks may be disabled by setting
format-placeholders key parameter of
dbi:connect to NIL.
Support for CLOB fields
CLOB fields may be used in INSERT operations.
(let ((long-string (make-string 22000 :initial-element #\a)) (query (dbi:prepare "INSERT INTO tbl (clob_field) VALUES ( ?)"))) (dbi:execute query (list long-string)))
You can not SELECT the value back, as ORACLE strips CLOB values to a predefined limit, which is 4000 for modern versions of ORACLE.
Extensions to DBI interface
The library supports single parse, multiple bind/executes loop for a statement.
(with-reusable-query (query connection "INSERT INTO tbl (k) VALUES ( ?)") (loop for k from 1 to 100 do (dbi:execute query (list k))))
This scheme may be more efficient when evaluating large number of
with-reusable-query evaluates its body with
being prepared SQL expressions, and ensures that all resources
allocated for the query will be released at the end.
The library was manually tested using Oracle 11g server under following client configurations:
- 64-bit Clozure CL 1.9 under Windows 7 using 64-bit version of Oracle instant client 184.108.40.206
- 64-bit SBCL 1.3.2 under Ubuntu 14.04 64-bit using Oracle instant client 220.127.116.11
- 32-bit LispWorks Personal Edition on Mac OS X 10.10 using 32-bit version of Oracle instant client 18.104.22.168
Automated testing uses SBCL under Linux, and Oracle XE version 11.2.
Testig procedure requires that the databse contain a table
CREATE TABLE realval ( r REAL, n NUMBER, ns NUMBER(*, 5), nps NUMBER(10, 2), i INTEGER ); INSERT INTO realval VALUES (17.17, 17.17, 17.17, 17.17, 17);
In order to run tests locally, you need to modify connection-related
test/root.lisp, or modify your environment in
accordance with the default values:
(deftestsuite root () ((user-name "scott") (password "tiger") (connect-string (let ((host "127.0.0.1") (port "1521") (oracle-sid (or (dbd.oracle::getenv "ORACLE_SID") "orcl"))) (format nil "~A:~A/~A" host port oracle-sid)))) (:dynamic-variables (dbd.oracle:*foreign-library-search-paths* '(#p"/opt/oracle/"))) ...)
Tests can be started using
Lisp Lesser GNU Public License