@c =================================================================== @c
@c    serrano/prgm/project/bigloo/manuals/sqlite.texi                  @c
@c    ------------------------------------------------------------     @c
@c    Author      :  Manuel Serrano                                    @c
@c    Creation    :  Fri Feb 10 07:37:26 2006                          @c
@c    Last change :                                                    @c
@c    Copyright   :  2006 Manuel Serrano                               @c
@c    ------------------------------------------------------------     @c
@c    SQLite binding                                                   @c
@c =================================================================== @c

@c ------------------------------------------------------------------- @c
@c    SQLite ...                                                       @c
@c ------------------------------------------------------------------- @c
@node SQLite, , , Database
@comment  node-name,  next,  previous,  up
@section SQLite
@cindex SQLITE

The Bigloo's C back-end supports SQL queries. It relies on the SQLite
library (@url{http://www.sqlite.org/}). The SQLite binding is accessible
to Bigloo via the @code{sqlite} library. Here is an example of module
that uses this library.

@smalllisp
(module example1
  (library sqlite))

(let ((db (instantiate::sqlite)))
  ...)
@end smalllisp

@deffn {bigloo sqlite class} sqlite
@smalllisp
(class sqlite
   (path::bstring read-only (default ":memory:")))
@end smalllisp

The instances of the class @code{sqlite} hold SQLite databases. A database
may be permanently stored on a disk or loaded in memory. The class attribute
@code{path} is the location on the disk where the database is stored. The
special path @code{:memory:} denotes in-memory databases. When an instance
is created a SQLite database is @emph{opened}.

Example:
@smalllisp
(define db1 (instantiate::sqlite (path "/tmp/foo.db")))
(define db2 (instantiate::sqlite))
@end smalllisp

Binds the global variable @var{db1} to a database that is stored on the file
system at location @code{/tmp/foo.db}. This example also binds the global
variable @var{db2} to an in-memory SQLite database.
@end deffn

@deffn {bigloo sqlite function} sqlite-close @var{sqlite}
This function closes a database previously opened by creating an instance
of the class @code{sqlite}.

Example:
@smalllisp
(let ((db (instantiate::sqlite)))
  (sqlite-exec db "CREATE TABLE table1 (x INTEGER, y INTEGER)")
  (sqlite-exec db "INSERT INTO table1 VALUES( ~a, ~a )" 1 4)
  (sqlite-close db))
@end smalllisp
@end deffn

@deffn {bigloo sqlite function} sqlite-format @var{string} @var{arg} @dots{}
Constructs a string of characters representing an SQLite
commands. This function acts as @code{format} (see @ref{Input and
Output}). It is augmented with three additional escape sequence:
@code{~q}, @code{~k}, and @code{~l}. The first one build a string of
characters where the characters denoting SQL strings (i.e., the
character @code{'}) is automatically escaped. The escape character
@code{~k} introduces a list of SQL strings. The escape character
@code{~l} introduces a SQL list.

Summary of all escape codes:
@itemize @bullet
@item @code{~a} The corresponding value is inserted into the string 
as if printed with display.
@item @code{~s} The corresponding value is inserted into the string 
as if printed with write.
@item @code{~%} A newline is inserted.
@item @code{~~} A tilde @code{~} is inserted.
@item @code{~q} An SQL escaped string.
@item @code{~l} Introduces a list (comma separated).
@item @code{~k} Introduces a list of SQL strings.
@end itemize

Examples:

@smalllisp
(module example
   (library sqlite))

(sqlite-format "~a" "foo'bar") @result{} "foo'bar"
(sqlite-format "~q" "foo'bar") @result{} "'foo''bar'"
(sqlite-format "~a" '("foo'bar" "foo")) @result{} "(foo'bar foo)"
(sqlite-format "~k" '("foo'bar" "foo")) @result{} "'foo''bar','foo'"
(sqlite-format "~l" '("foo'bar" "foo")) @result{} "foo'bar,foo"
@end smalllisp
@end deffn

@deffn {bigloo sqlite function} sqlite-exec @var{sqlite} @var{string} @var{arg} @dots{}
The function @code{sqlite-exec} @emph{executes} an SQLite command. The command
is the built by implicitly invoking @code{sqlite-format} on @var{string} and
the optional @var{arg} arguments. This function returns a single element,
the first one returned by the SQL engine.

Example:
@smalllisp
(module example
   (library sqlite))

(define *db* (instantiate::sqlite))

(sqlite-exec *db* "CREATE TABLE foo (x INTEGER, y INTEGER)")
(for-each (lambda (x)
		(sqlite-exec *db*  "INSERT INTO foo VALUES(~A, ~A)" x (* x x)))
	     (iota 10))
(sqlite-exec *db* "SELECT * FROM foo")
   @result{} 9
@end smalllisp

@end deffn

@deffn {bigloo sqlite function} sqlite-eval @var{sqlite} @var{procedure} @var{string} @var{arg} @dots{}
The function @code{sqlite-eval} invokes a SQLite command built by
implicitly invoking @code{sqlite-format} on @var{string} and the optional
@var{arg} arguments. The result of the function is built by applying 
@var{procedure} to the first value returned by the SQLite call.

Note: user callback (@var{procedure}) @b{must not} exit. That is they must
not invoke a function create by @code{bind-exit}. Exiting from a callback will
leave the database in a inconsistent state that prevent transactions to
be rolled back.
@end deffn

@deffn {bigloo sqlite function} sqlite-map @var{sqlite} @var{procedure} @var{string} @var{arg} @dots{}
The function @code{sqlite-map} invokes a SQLite command built by
implicitly invoking @code{sqlite-format} on @var{string} and the optional
@var{arg} arguments. The result is a list whose elements are built by applying 
@var{procedure} to all the values returned by the SQLite call.

Note: user callback (@var{procedure}) @b{must not} exit. That is they must
not invoke a function create by @code{bind-exit}. Exiting from a callback will
leave the database in a inconsistent state that prevent transactions to
be rolled back.
Example:

@smalllisp
(module example
   (library sqlite))

(define *db* (instantiate::sqlite))

(sqlite-exec *db* "CREATE TABLE foo (x INTEGER, y INTEGER)")
(for-each (lambda (x)
		(sqlite-exec *db*  "INSERT INTO foo VALUES(~A, ~A)" x (* x x)))
	     (iota 10))
(sqlite-map *db* 
  (lambda (s1 s2) (+ (string->integer s1) (string->integer s2))) 
  "SELECT * FROM foo")
   @result{} (0 2 6 12 20 30 42 56 72 90)
@end smalllisp
@end deffn

Example2:
@smalllisp
(module example
   (library sqlite))

(define *db* (instantiate::sqlite))

(sqlite-exec *db* "CREATE TABLE foo (x INTEGER, y INTEGER)")
(for-each (lambda (x)
		(sqlite-exec *db*  "INSERT INTO foo VALUES(~A, ~A)" x (* x x)))
	     (iota 10))
(sqlite-map *db* vector "SELECT * FROM foo")
   @result{} '(#("0" "0")
	#("1" "1")
	#("2" "4")
	#("3" "9")
	#("4" "16")
	#("5" "25")
	#("6" "36")
	#("7" "49")
	#("8" "64")
	#("9" "81"))
@end smalllisp

@deffn {bigloo sqlite function} sqlite-name-of-tables @var{sqlite}
Returns the name of tables in the database. This list can also be
obtained with

@smalllisp
(sqlite-map db
   (lambda (x) x)
   "SELECT name FROM sqlite_master WHERE type='table'")
@end smalllisp
@end deffn

@deffn {bigloo sqlite function} sqlite-table-name-of-columns @var{sqlite} @var{table}
Returns the name of columns in the table.
@end deffn

@deffn {bigloo sqlite function} sqlite-last-insert-rowid @var{sqlite}
Returns the SQLite @emph{rowid} of the last inserted row.
@end deffn





