! Copyright (C) 2008 Doug Coleman.
+! Copyright (C) 2018 Alexander Ilin.
! See http://factorcode.org/license.txt for BSD license.
-USING: classes help.markup help.syntax io.streams.string kernel
-quotations sequences strings math db.types db.tuples.private db ;
+USING: classes db db.tuples.private db.types help.markup
+help.syntax kernel math quotations sequences strings ;
IN: db.tuples
HELP: random-id-generator
{ "tuple" tuple } }
{ $description "Updates a tuple that has already been inserted into a database. The tuple must have a primary key that has been set by " { $link insert-tuple } " or that is user-defined." } ;
+HELP: update-tuples
+{ $values
+ { "query/tuple" tuple }
+ { "quot" { $quotation ( tuple -- tuple'/f ) } } }
+{ $description "An SQL query is constructed from the slots of the exemplar tuple that are not " { $link f } ". The " { $snippet "quot" } " is applied to each tuple from the database that matches the query, and the changed tuple is stored back to the database. If the " { $snippet "quot" } " returns " { $link f } ", the tuple is dropped, and its data remains unmodified in the database."
+$nl
+"The word is equivalent to the following code:"
+{ $code "query/tuple select-tuples quot map sift [ update-tuple ] each" }
+"The difference is that " { $snippet "update-tuples" } " handles query results one by one, thus avoiding the overhead of allocating the intermediate array of tuples, which " { $link select-tuples } " would do. This is important when processing large amounts of data in limited memory." } ;
+
HELP: delete-tuples
{ $values
{ "tuple" tuple } }
{ $description "Uses the " { $snippet "tuple" } " as an exemplar object and deletes any objects that have the same slots set. If a slot is not " { $link f } ", then it is used to generate an SQL statement that deletes tuples." }
{ $warning "This word will delete your data." } ;
-{ insert-tuple update-tuple delete-tuples } related-words
+HELP: reject-tuples
+{ $values
+ { "query/tuple" tuple }
+ { "quot" { $quotation ( tuple -- ? ) } } }
+{ $description "An SQL query is constructed from the slots of the exemplar tuple that are not " { $link f } ". The " { $snippet "quot" } " is applied to each tuple from the database that matches the query, and if it returns a true value, the row is deleted from the database."
+$nl
+"The word is equivalent to the following code:"
+{ $code "query/tuple select-tuples quot filter [ delete-tuples ] each" }
+"The difference is that " { $snippet "reject-tuples" } " handles query results one by one, thus avoiding the overhead of allocating the intermediate array of tuples, which " { $link select-tuples } " would do. This is important when processing large amounts of data in limited memory." }
+{ $warning "This word will delete your data." } ;
+
+{ insert-tuple update-tuple update-tuples delete-tuples reject-tuples } related-words
+
+HELP: each-tuple
+{ $values
+ { "query/tuple" tuple }
+ { "quot" { $quotation ( tuple -- ) } } }
+{ $description "An SQL query is constructed from the slots of the exemplar tuple that are not " { $link f } ". The " { $snippet "quot" } " is applied to each tuple from the database that matches the query constructed from the exemplar tuple." } ;
HELP: select-tuple
{ $values
{ "query/tuple" tuple }
{ "tuple/f" { $maybe tuple } } }
-{ $description "A SQL query is constructed from the slots of the exemplar tuple that are not " { $link f } ". Returns a single tuple from the database if it matches the query constructed from the exemplar tuple." } ;
+{ $description "An SQL query is constructed from the slots of the exemplar tuple that are not " { $link f } ". Returns a single tuple from the database if it matches the query constructed from the exemplar tuple." } ;
HELP: select-tuples
{ $values
{ "query/tuple" tuple }
{ "tuples" "an array of tuples" } }
-{ $description "A SQL query is constructed from the slots of the exemplar tuple that are not " { $link f } ". Returns an array of multiple tuples from the database that match the query constructed from the exemplar tuple." } ;
+{ $description "An SQL query is constructed from the slots of the exemplar tuple that are not " { $link f } ". Returns an array of multiple tuples from the database that match the query constructed from the exemplar tuple." } ;
HELP: count-tuples
{ $values
{ "n" integer } }
{ $description "Returns the number of items that would be returned if the query were a select query. Counting the tuples with this word is more efficient than calling " { $link length } " on the result of " { $link select-tuples } "." } ;
-{ select-tuple select-tuples count-tuples } related-words
+{ each-tuple select-tuple select-tuples count-tuples } related-words
{ $subsections drop-table }
"Inserting a tuple:"
{ $subsections insert-tuple }
-"Updating a tuple:"
-{ $subsections update-tuple }
+"Updating tuples:"
+{ $subsections
+ update-tuple
+ update-tuples
+}
"Deleting tuples:"
-{ $subsections delete-tuples }
+{ $subsections
+ delete-tuples
+ reject-tuples
+}
"Querying tuples:"
{ $subsections
+ each-tuple
select-tuple
select-tuples
count-tuples
"Let's make a tuple and store it in a database. To follow along, click on each code example and run it in the listener. If you forget to run an example, just start at the top and run them all again in order." $nl
"We're going to store books in this tutorial."
{ $code "TUPLE: book id title author date-published edition cover-price condition ;" }
-"The title, author, and publisher should be strings; the date-published a timestamp; the edition an integer; the cover-price a float. These are the Factor types for which we will need to look up the corresponding " { $link "db.types" } ". " $nl
+"The title, author, and publisher should be strings; the date-published a timestamp; the edition an integer; the cover-price a float. These are the Factor types for which we will need to look up the corresponding " { $link "db.types" } "." $nl
"To actually bind the tuple slots to the database types, we'll use " { $link define-persistent } "."
{ $code
"USING: db.tuples db.types ;
projects / factor.git / blobdiff