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diff --git a/user_guide_src/source/database/active_record.rst b/user_guide_src/source/database/active_record.rst new file mode 100644 index 000000000..e1fc00bc5 --- /dev/null +++ b/user_guide_src/source/database/active_record.rst @@ -0,0 +1,856 @@ +################### +Active Record Class +################### + +CodeIgniter uses a modified version of the Active Record Database +Pattern. This pattern allows information to be retrieved, inserted, and +updated in your database with minimal scripting. In some cases only one +or two lines of code are necessary to perform a database action. +CodeIgniter does not require that each database table be its own class +file. It instead provides a more simplified interface. + +Beyond simplicity, a major benefit to using the Active Record features +is that it allows you to create database independent applications, since +the query syntax is generated by each database adapter. It also allows +for safer queries, since the values are escaped automatically by the +system. + +.. note:: If you intend to write your own queries you can disable this + class in your database config file, allowing the core database library + and adapter to utilize fewer resources. + +.. contents:: Page Contents + +************** +Selecting Data +************** + +The following functions allow you to build SQL **SELECT** statements. + +$this->db->get() +================ + +Runs the selection query and returns the result. Can be used by itself +to retrieve all records from a table:: + + $query = $this->db->get('mytable'); // Produces: SELECT * FROM mytable + +The second and third parameters enable you to set a limit and offset +clause:: + + $query = $this->db->get('mytable', 10, 20); + // Produces: SELECT * FROM mytable LIMIT 20, 10 (in MySQL. Other databases have slightly different syntax) + +You'll notice that the above function is assigned to a variable named +$query, which can be used to show the results:: + + $query = $this->db->get('mytable'); + + foreach ($query->result() as $row) + { + echo $row->title; + } + +Please visit the :doc:`result functions <results>` page for a full +discussion regarding result generation. + +$this->db->get_where() +====================== + +Identical to the above function except that it permits you to add a +"where" clause in the second parameter, instead of using the db->where() +function:: + + $query = $this->db->get_where('mytable', array('id' => $id), $limit, $offset); + +Please read the about the where function below for more information. + +Note: get_where() was formerly known as getwhere(), which has been +removed + +$this->db->select() +=================== + +Permits you to write the SELECT portion of your query:: + + $this->db->select('title, content, date'); + $query = $this->db->get('mytable'); // Produces: SELECT title, content, date FROM mytable + + +.. note:: If you are selecting all (\*) from a table you do not need to + use this function. When omitted, CodeIgniter assumes you wish to SELECT * + +$this->db->select() accepts an optional second parameter. If you set it +to FALSE, CodeIgniter will not try to protect your field or table names +with backticks. This is useful if you need a compound select statement. + +:: + + $this->db->select('(SELECT SUM(payments.amount) FROM payments WHERE payments.invoice_id=4') AS amount_paid', FALSE); + $query = $this->db->get('mytable'); + + +$this->db->select_max() +======================= + +Writes a "SELECT MAX(field)" portion for your query. You can optionally +include a second parameter to rename the resulting field. + +:: + + $this->db->select_max('age'); + $query = $this->db->get('members'); // Produces: SELECT MAX(age) as age FROM members + + $this->db->select_max('age', 'member_age'); + $query = $this->db->get('members'); // Produces: SELECT MAX(age) as member_age FROM members + + +$this->db->select_min() +======================= + +Writes a "SELECT MIN(field)" portion for your query. As with +select_max(), You can optionally include a second parameter to rename +the resulting field. + +:: + + $this->db->select_min('age'); + $query = $this->db->get('members'); // Produces: SELECT MIN(age) as age FROM members + + +$this->db->select_avg() +======================= + +Writes a "SELECT AVG(field)" portion for your query. As with +select_max(), You can optionally include a second parameter to rename +the resulting field. + +:: + + $this->db->select_avg('age'); + $query = $this->db->get('members'); // Produces: SELECT AVG(age) as age FROM members + + +$this->db->select_sum() +======================= + +Writes a "SELECT SUM(field)" portion for your query. As with +select_max(), You can optionally include a second parameter to rename +the resulting field. + +:: + + $this->db->select_sum('age'); + $query = $this->db->get('members'); // Produces: SELECT SUM(age) as age FROM members + + +$this->db->from() +================= + +Permits you to write the FROM portion of your query:: + + $this->db->select('title, content, date'); + $this->db->from('mytable'); + $query = $this->db->get(); // Produces: SELECT title, content, date FROM mytable + +.. note:: As shown earlier, the FROM portion of your query can be specified + in the $this->db->get() function, so use whichever method you prefer. + +$this->db->join() +================= + +Permits you to write the JOIN portion of your query:: + + $this->db->select('*'); + $this->db->from('blogs'); + $this->db->join('comments', 'comments.id = blogs.id'); + $query = $this->db->get(); + + // Produces: + // SELECT * FROM blogs // JOIN comments ON comments.id = blogs.id + +Multiple function calls can be made if you need several joins in one +query. + +If you need a specific type of JOIN you can specify it via the third +parameter of the function. Options are: left, right, outer, inner, left +outer, and right outer. + +:: + + $this->db->join('comments', 'comments.id = blogs.id', 'left'); + // Produces: LEFT JOIN comments ON comments.id = blogs.id + +$this->db->where() +================== + +This function enables you to set **WHERE** clauses using one of four +methods: + +.. note:: All values passed to this function are escaped automatically, + producing safer queries. + +#. **Simple key/value method:** + + :: + + $this->db->where('name', $name); // Produces: WHERE name = 'Joe' + + Notice that the equal sign is added for you. + + If you use multiple function calls they will be chained together with + AND between them: + + :: + + $this->db->where('name', $name); + $this->db->where('title', $title); + $this->db->where('status', $status); + // WHERE name = 'Joe' AND title = 'boss' AND status = 'active' + +#. **Custom key/value method:** + You can include an operator in the first parameter in order to + control the comparison: + + :: + + $this->db->where('name !=', $name); + $this->db->where('id <', $id); // Produces: WHERE name != 'Joe' AND id < 45 + +#. **Associative array method:** + + :: + + $array = array('name' => $name, 'title' => $title, 'status' => $status); + $this->db->where($array); + // Produces: WHERE name = 'Joe' AND title = 'boss' AND status = 'active' + + You can include your own operators using this method as well: + + :: + + $array = array('name !=' => $name, 'id <' => $id, 'date >' => $date); + $this->db->where($array); + +#. **Custom string:** + You can write your own clauses manually:: + + $where = "name='Joe' AND status='boss' OR status='active'"; + $this->db->where($where); + + +$this->db->where() accepts an optional third parameter. If you set it to +FALSE, CodeIgniter will not try to protect your field or table names +with backticks. + +:: + + $this->db->where('MATCH (field) AGAINST ("value")', NULL, FALSE); + + +$this->db->or_where() +===================== + +This function is identical to the one above, except that multiple +instances are joined by OR:: + + $this->db->where('name !=', $name); + $this->db->or_where('id >', $id); // Produces: WHERE name != 'Joe' OR id > 50 + +.. note:: or_where() was formerly known as orwhere(), which has been + removed. + +$this->db->where_in() +===================== + +Generates a WHERE field IN ('item', 'item') SQL query joined with AND if +appropriate + +:: + + $names = array('Frank', 'Todd', 'James'); + $this->db->where_in('username', $names); + // Produces: WHERE username IN ('Frank', 'Todd', 'James') + + +$this->db->or_where_in() +======================== + +Generates a WHERE field IN ('item', 'item') SQL query joined with OR if +appropriate + +:: + + $names = array('Frank', 'Todd', 'James'); + $this->db->or_where_in('username', $names); + // Produces: OR username IN ('Frank', 'Todd', 'James') + + +$this->db->where_not_in() +========================= + +Generates a WHERE field NOT IN ('item', 'item') SQL query joined with +AND if appropriate + +:: + + $names = array('Frank', 'Todd', 'James'); + $this->db->where_not_in('username', $names); + // Produces: WHERE username NOT IN ('Frank', 'Todd', 'James') + + +$this->db->or_where_not_in() +============================ + +Generates a WHERE field NOT IN ('item', 'item') SQL query joined with OR +if appropriate + +:: + + $names = array('Frank', 'Todd', 'James'); + $this->db->or_where_not_in('username', $names); + // Produces: OR username NOT IN ('Frank', 'Todd', 'James') + + +$this->db->like() +================= + +This function enables you to generate **LIKE** clauses, useful for doing +searches. + +.. note:: All values passed to this function are escaped automatically. + +#. **Simple key/value method:** + + :: + + $this->db->like('title', 'match'); // Produces: WHERE title LIKE '%match%' + + If you use multiple function calls they will be chained together with + AND between them:: + + $this->db->like('title', 'match'); + $this->db->like('body', 'match'); + // WHERE title LIKE '%match%' AND body LIKE '%match% + + If you want to control where the wildcard (%) is placed, you can use + an optional third argument. Your options are 'before', 'after' and + 'both' (which is the default). + + :: + + $this->db->like('title', 'match', 'before'); // Produces: WHERE title LIKE '%match' + $this->db->like('title', 'match', 'after'); // Produces: WHERE title LIKE 'match%' + $this->db->like('title', 'match', 'both'); // Produces: WHERE title LIKE '%match%' + +#. **Associative array method:** + + :: + + $array = array('title' => $match, 'page1' => $match, 'page2' => $match); + $this->db->like($array); + // WHERE title LIKE '%match%' AND page1 LIKE '%match%' AND page2 LIKE '%match%' + + +$this->db->or_like() +==================== + +This function is identical to the one above, except that multiple +instances are joined by OR:: + + $this->db->like('title', 'match'); $this->db->or_like('body', $match); + // WHERE title LIKE '%match%' OR body LIKE '%match%' + +.. note:: or_like() was formerly known as orlike(), which has been removed. + +$this->db->not_like() +===================== + +This function is identical to **like()**, except that it generates NOT +LIKE statements:: + + $this->db->not_like('title', 'match'); // WHERE title NOT LIKE '%match% + +$this->db->or_not_like() +======================== + +This function is identical to **not_like()**, except that multiple +instances are joined by OR:: + + $this->db->like('title', 'match'); + $this->db->or_not_like('body', 'match'); + // WHERE title LIKE '%match% OR body NOT LIKE '%match%' + +$this->db->group_by() +===================== + +Permits you to write the GROUP BY portion of your query:: + + $this->db->group_by("title"); // Produces: GROUP BY title + +You can also pass an array of multiple values as well:: + + $this->db->group_by(array("title", "date")); // Produces: GROUP BY title, date + +.. note:: group_by() was formerly known as groupby(), which has been + removed. + +$this->db->distinct() +===================== + +Adds the "DISTINCT" keyword to a query + +:: + + $this->db->distinct(); + $this->db->get('table'); // Produces: SELECT DISTINCT * FROM table + + +$this->db->having() +=================== + +Permits you to write the HAVING portion of your query. There are 2 +possible syntaxes, 1 argument or 2:: + + $this->db->having('user_id = 45'); // Produces: HAVING user_id = 45 + $this->db->having('user_id', 45); // Produces: HAVING user_id = 45 + +You can also pass an array of multiple values as well:: + + $this->db->having(array('title =' => 'My Title', 'id <' => $id)); + // Produces: HAVING title = 'My Title', id < 45 + + +If you are using a database that CodeIgniter escapes queries for, you +can prevent escaping content by passing an optional third argument, and +setting it to FALSE. + +:: + + $this->db->having('user_id', 45); // Produces: HAVING `user_id` = 45 in some databases such as MySQL + $this->db->having('user_id', 45, FALSE); // Produces: HAVING user_id = 45 + + +$this->db->or_having() +====================== + +Identical to having(), only separates multiple clauses with "OR". + +$this->db->order_by() +===================== + +Lets you set an ORDER BY clause. The first parameter contains the name +of the column you would like to order by. The second parameter lets you +set the direction of the result. Options are asc or desc, or random. + +:: + + $this->db->order_by("title", "desc"); // Produces: ORDER BY title DESC + +You can also pass your own string in the first parameter:: + + $this->db->order_by('title desc, name asc'); // Produces: ORDER BY title DESC, name ASC + +Or multiple function calls can be made if you need multiple fields. + +:: + + $this->db->order_by("title", "desc"); + $this->db->order_by("name", "asc"); // Produces: ORDER BY title DESC, name ASC + + +.. note:: order_by() was formerly known as orderby(), which has been + removed. + +.. note:: random ordering is not currently supported in Oracle or MSSQL + drivers. These will default to 'ASC'. + +$this->db->limit() +================== + +Lets you limit the number of rows you would like returned by the query:: + + $this->db->limit(10); // Produces: LIMIT 10 + +The second parameter lets you set a result offset. + +:: + + $this->db->limit(10, 20); // Produces: LIMIT 20, 10 (in MySQL. Other databases have slightly different syntax) + +$this->db->count_all_results() +============================== + +Permits you to determine the number of rows in a particular Active +Record query. Queries will accept Active Record restrictors such as +where(), or_where(), like(), or_like(), etc. Example:: + + echo $this->db->count_all_results('my_table'); // Produces an integer, like 25 + $this->db->like('title', 'match'); + $this->db->from('my_table'); + echo $this->db->count_all_results(); // Produces an integer, like 17 + +$this->db->count_all() +====================== + +Permits you to determine the number of rows in a particular table. +Submit the table name in the first parameter. Example:: + + echo $this->db->count_all('my_table'); // Produces an integer, like 25 + +************** +Inserting Data +************** + +$this->db->insert() +=================== + +Generates an insert string based on the data you supply, and runs the +query. You can either pass an **array** or an **object** to the +function. Here is an example using an array:: + + $data = array( + 'title' => 'My title', + 'name' => 'My Name', + 'date' => 'My date' + ); + + $this->db->insert('mytable', $data); + // Produces: INSERT INTO mytable (title, name, date) VALUES ('My title', 'My name', 'My date') + +The first parameter will contain the table name, the second is an +associative array of values. + +Here is an example using an object:: + + /* + class Myclass { + var $title = 'My Title'; + var $content = 'My Content'; + var $date = 'My Date'; + } + */ + + $object = new Myclass; + $this->db->insert('mytable', $object); + // Produces: INSERT INTO mytable (title, content, date) VALUES ('My Title', 'My Content', 'My Date') + +The first parameter will contain the table name, the second is an +object. + +.. note:: All values are escaped automatically producing safer queries. + +$this->db->insert_batch() +========================= + +Generates an insert string based on the data you supply, and runs the +query. You can either pass an **array** or an **object** to the +function. Here is an example using an array:: + + $data = array( + array( + 'title' => 'My title', + 'name' => 'My Name', + 'date' => 'My date' + ), + array( + 'title' => 'Another title', + 'name' => 'Another Name', + 'date' => 'Another date' + ) + ); + + $this->db->insert_batch('mytable', $data); + // Produces: INSERT INTO mytable (title, name, date) VALUES ('My title', 'My name', 'My date'), ('Another title', 'Another name', 'Another date') + +The first parameter will contain the table name, the second is an +associative array of values. + +.. note:: All values are escaped automatically producing safer queries. + +$this->db->set() +================ + +This function enables you to set values for inserts or updates. + +**It can be used instead of passing a data array directly to the insert +or update functions:** + +:: + + $this->db->set('name', $name); + $this->db->insert('mytable'); // Produces: INSERT INTO mytable (name) VALUES ('{$name}') + +If you use multiple function called they will be assembled properly +based on whether you are doing an insert or an update:: + + $this->db->set('name', $name); + $this->db->set('title', $title); + $this->db->set('status', $status); + $this->db->insert('mytable'); + +**set()** will also accept an optional third parameter ($escape), that +will prevent data from being escaped if set to FALSE. To illustrate the +difference, here is set() used both with and without the escape +parameter. + +:: + + $this->db->set('field', 'field+1', FALSE); + $this->db->insert('mytable'); // gives INSERT INTO mytable (field) VALUES (field+1) + $this->db->set('field', 'field+1'); + $this->db->insert('mytable'); // gives INSERT INTO mytable (field) VALUES ('field+1') + + +You can also pass an associative array to this function:: + + $array = array( + 'name' => $name, + 'title' => $title, + 'status' => $status + ); + + $this->db->set($array); + $this->db->insert('mytable'); + +Or an object:: + + /* + class Myclass { + var $title = 'My Title'; + var $content = 'My Content'; + var $date = 'My Date'; + } + */ + + $object = new Myclass; + $this->db->set($object); + $this->db->insert('mytable'); + + +************* +Updating Data +************* + +$this->db->update() +=================== + +Generates an update string and runs the query based on the data you +supply. You can pass an **array** or an **object** to the function. Here +is an example using an array:: + + $data = array( + 'title' => $title, + 'name' => $name, + 'date' => $date + ); + + $this->db->where('id', $id); + $this->db->update('mytable', $data); + // Produces: // UPDATE mytable // SET title = '{$title}', name = '{$name}', date = '{$date}' // WHERE id = $id + +Or you can supply an object:: + + /* + class Myclass { + var $title = 'My Title'; + var $content = 'My Content'; + var $date = 'My Date'; + } + */ + + $object = new Myclass; + $this->db->where('id', $id); + $this->db->update('mytable', $object); + // Produces: // UPDATE mytable // SET title = '{$title}', name = '{$name}', date = '{$date}' // WHERE id = $id + +.. note:: All values are escaped automatically producing safer queries. + +You'll notice the use of the $this->db->where() function, enabling you +to set the WHERE clause. You can optionally pass this information +directly into the update function as a string:: + + $this->db->update('mytable', $data, "id = 4"); + +Or as an array:: + + $this->db->update('mytable', $data, array('id' => $id)); + +You may also use the $this->db->set() function described above when +performing updates. + +$this->db->update_batch() +========================= + +Generates an update string based on the data you supply, and runs the query. +You can either pass an **array** or an **object** to the function. +Here is an example using an array:: + + $data = array( + array( + 'title' => 'My title' , + 'name' => 'My Name 2' , + 'date' => 'My date 2' + ), + array( + 'title' => 'Another title' , + 'name' => 'Another Name 2' , + 'date' => 'Another date 2' + ) + ); + + $this->db->update_batch('mytable', $data, 'title'); + + // Produces: + // UPDATE `mytable` SET `name` = CASE + // WHEN `title` = 'My title' THEN 'My Name 2' + // WHEN `title` = 'Another title' THEN 'Another Name 2' + // ELSE `name` END, + // `date` = CASE + // WHEN `title` = 'My title' THEN 'My date 2' + // WHEN `title` = 'Another title' THEN 'Another date 2' + // ELSE `date` END + // WHERE `title` IN ('My title','Another title') + +The first parameter will contain the table name, the second is an associative +array of values, the third parameter is the where key. + +.. note:: All values are escaped automatically producing safer queries. + + +************* +Deleting Data +************* + +$this->db->delete() +=================== + +Generates a delete SQL string and runs the query. + +:: + + $this->db->delete('mytable', array('id' => $id)); // Produces: // DELETE FROM mytable // WHERE id = $id + +The first parameter is the table name, the second is the where clause. +You can also use the where() or or_where() functions instead of passing +the data to the second parameter of the function:: + + $this->db->where('id', $id); + $this->db->delete('mytable'); + + // Produces: + // DELETE FROM mytable + // WHERE id = $id + + +An array of table names can be passed into delete() if you would like to +delete data from more than 1 table. + +:: + + $tables = array('table1', 'table2', 'table3'); + $this->db->where('id', '5'); + $this->db->delete($tables); + + +If you want to delete all data from a table, you can use the truncate() +function, or empty_table(). + +$this->db->empty_table() +======================== + +Generates a delete SQL string and runs the +query.:: + + $this->db->empty_table('mytable'); // Produces // DELETE FROM mytable + + +$this->db->truncate() +===================== + +Generates a truncate SQL string and runs the query. + +:: + + $this->db->from('mytable'); + $this->db->truncate(); + + // or + + $this->db->truncate('mytable'); + + // Produce: + // TRUNCATE mytable + +.. note:: If the TRUNCATE command isn't available, truncate() will + execute as "DELETE FROM table". + +*************** +Method Chaining +*************** + +Method chaining allows you to simplify your syntax by connecting +multiple functions. Consider this example:: + + $query = $this->db->select('title') + ->where('id', $id) + ->limit(10, 20) + ->get('mytable'); + +.. note:: Method chaining only works with PHP 5. + +.. _ar-caching: + +********************* +Active Record Caching +********************* + +While not "true" caching, Active Record enables you to save (or "cache") +certain parts of your queries for reuse at a later point in your +script's execution. Normally, when an Active Record call is completed, +all stored information is reset for the next call. With caching, you can +prevent this reset, and reuse information easily. + +Cached calls are cumulative. If you make 2 cached select() calls, and +then 2 uncached select() calls, this will result in 4 select() calls. +There are three Caching functions available: + +$this->db->start_cache() +======================== + +This function must be called to begin caching. All Active Record queries +of the correct type (see below for supported queries) are stored for +later use. + +$this->db->stop_cache() +======================= + +This function can be called to stop caching. + +$this->db->flush_cache() +======================== + +This function deletes all items from the Active Record cache. + +Here's a usage example:: + + $this->db->start_cache(); + $this->db->select('field1'); + $this->db->stop_cache(); + $this->db->get('tablename'); + //Generates: SELECT `field1` FROM (`tablename`) + + $this->db->select('field2'); + $this->db->get('tablename'); + //Generates: SELECT `field1`, `field2` FROM (`tablename`) + + $this->db->flush_cache(); + $this->db->select('field2'); + $this->db->get('tablename'); + //Generates: SELECT `field2` FROM (`tablename`) + + +.. note:: The following statements can be cached: select, from, join, + where, like, group_by, having, order_by, set + + |