db: fix some examples

db4
Keita Haga 2010-11-28 03:34:27 +09:00
parent 18811fb04a
commit 2dbee396fb
1 changed files with 7 additions and 11 deletions

View File

@ -271,24 +271,21 @@ ARTICLE: "db-lowlevel-tutorial" "Low-level database tutorial"
{ $subsections sql-query }
"Here's an example usage where we'll make a book table, insert some objects, and query them." $nl
"First, let's set up a custom combinator for using our database. See " { $link "db-custom-database-combinators" } " for more details."
{ $code """
USING: db.sqlite db io.files io.files.temp ;
{ $code """USING: db.sqlite db io.files io.files.temp ;
: with-book-db ( quot -- )
"book.db" temp-file <sqlite-db> swap with-db ; inline" }
"book.db" temp-file <sqlite-db> swap with-db ; inline""" }
"Now let's create the table manually:"
{ $code " "create table books
{ $code """"create table books
(id integer primary key, title text, author text, date_published timestamp,
edition integer, cover_price double, condition text)"
[ sql-command ] with-book-db""" }
"Time to insert some books:"
{ $code """
"insert into books
{ $code """"insert into books
(title, author, date_published, edition, cover_price, condition)
values('Factor for Sheeple', 'Mister Stacky Pants', date('now'), 1, 13.37, 'mint')"
[ sql-command ] with-book-db""" }
"Now let's select the book:"
{ $code """
"select id, title, cover_price from books;" [ sql-query ] with-book-db""" }
{ $code """"select id, title, cover_price from books;" [ sql-query ] with-book-db""" }
"Notice that the result of this query is a Factor array containing the database rows as arrays of strings. We would have to convert the " { $snippet "cover_price" } " from a string to a number in order to use it in a calculation." $nl
"In conclusion, this method of accessing a database is supported, but it is fairly low-level and generally specific to a single database. The " { $vocab-link "db.tuples" } " vocabulary is a good alternative to writing SQL by hand." ;
@ -298,10 +295,9 @@ ARTICLE: "db-custom-database-combinators" "Custom database combinators"
"Make a " { $snippet "with-" } " combinator to open and close a database so that resources are not leaked." $nl
"SQLite example combinator:"
{ $code """
USING: db.sqlite db io.files io.files.temp ;
{ $code """USING: db.sqlite db io.files io.files.temp ;
: with-sqlite-db ( quot -- )
"my-database.db" temp-file <sqlite-db> swap with-db ; inline""" }
"my-database.db" temp-file <sqlite-db> swap with-db ; inline""" }
"PostgreSQL example combinator:"
{ $code """USING: db.postgresql db ;