It seems like there's a few different ways to join two tables using the Zend Framework, but I've never done it before so I don't know which is the best way to do it.
This is what I'm trying to do...
I have 3 tables in my database:
users
( id , name )
groups
( id , name )
group_members
( id , group_id , user_id )
I'm trying to look up the groups that a user belongs to and display that to the user. This SQL statement pretty much does the job (though there may be a better way to write it). It only returns the columns I'm concerned with which are the group's id and title.
SELECT groups.id, groups.title
FROM group_members
INNER JOIN groups
ON groups.id = group_members.group_id
WHERE user_id = $userId
How can I do this with the Zend Framework?
Finally figured out how to do it. If you've got a better way, please let me know.
$db = Zend_Db_Table::getDefaultAdapter(); //set in my config file
$select = new Zend_Db_Select($db);
$select->from('groups', array('id', 'title')) //the array specifies which columns I want returned in my result set
->joinInner(
'group_members',
'groups.id = group_members.group_id',
array()) //by specifying an empty array, I am saying that I don't care about the columns from this table
->where('user_id = ?', $userId);
$resultSet = $db->fetchAll($select);
This will return a table with only the id and title columns. The empty array() was the key to removing the columns I didn't care about. I could then do something with the result set.
foreach ($resultSet as $row) {
//do something with $row->id or $row->title
}
No need to using Join,we can use Zend_Db_Table instead for the reason about the MVC pattern. I got this idea form here,#10 by Filip.(maybe they call this "Table Data Gateway"?)
Related
I'm developing an extension for TYPO3 CMS 8.7.8. I'm using query->statement() to select all fields from a single table, plus 1 field from another table. I get a QueryResult with the proper models and I would like to have that 1 extra field added to them. Is that possible?
You can do SQL queries with the ->statement(...) method and in that, use normal JOIN commands
From the documentation
$result = $query->statement('SELECT * FROM tx_sjroffers_domain_model_offer
WHERE title LIKE ? AND organization IN ?', array('%climbing%', array(33,47)));
So you can do JOINs on whatever table you want to (also code from the documentation)
LEFT JOIN tx_blogexample_person
ON tx_blogexample_post.author = tx_blogexample_person.uid
But you will end up with the raw data from the mysql query. If you want to transform it into a object, use the Property Mapper
You can use JOIN in your sql statments like below.
$query = $this->createQuery();
$sql = 'SELECT single.*,another.field_anme AS fields_name
FROM
tx_single_table_name single
JOIN
tx_another_table_name another
ON
single.fields = another.uid
WHERE
O.deleted = 0
AND O.hidden=0
AND O.uid=' . $orderId;
return $query->statement($sql)->execute();
I'm very new to zend (1.12)..so please excuse my very basic question:
I want to fetch only one row from a database. Thatfore I want to use the fetchRow(..) function like this
$row = $db->fetchRow($db->select()->where("col1 = '".val1."' AND col2='".val2."'"));
The problem is, that there may be many rows that fit to the where-clause and I only want to get the one with the highest id. How can I do this?
The fetchRow() method returs only one row. If you want to choose row with the highest ID meeting other conditions, invoke it like this:
$select = $db->select()
->where('col1 = ?', $val1)
->where('col2 = ?', $val2)
->order('id DESC');
$row = $db->fetchRow($select);
Also, remember to pass values to SQL query in the way as in above code (to avoid SQL injection attack risk).
I'm using Flask-SQLAlchemy with PostgreSQL. I have the following two models:
class Course(db.Model):
id = db.Column(db.Integer, primary_key = True )
course_name =db.Column(db.String(120))
course_description = db.Column(db.Text)
course_reviews = db.relationship('Review', backref ='course', lazy ='dynamic')
class Review(db.Model):
__table_args__ = ( db.UniqueConstraint('course_id', 'user_id'), { } )
id = db.Column(db.Integer, primary_key = True )
review_date = db.Column(db.DateTime)#default=db.func.now()
review_comment = db.Column(db.Text)
rating = db.Column(db.SmallInteger)
course_id = db.Column(db.Integer, db.ForeignKey('course.id') )
user_id = db.Column(db.Integer, db.ForeignKey('user.id') )
I want to select the courses that are most reviewed starting with at least two reviews. The following SQLAlchemy query worked fine with SQlite:
most_rated_courses = db.session.query(models.Review, func.count(models.Review.course_id)).group_by(models.Review.course_id).\
having(func.count(models.Review.course_id) >1) \ .order_by(func.count(models.Review.course_id).desc()).all()
But when I switched to PostgreSQL in production it gives me the following error:
ProgrammingError: (ProgrammingError) column "review.id" must appear in the GROUP BY clause or be used in an aggregate function
LINE 1: SELECT review.id AS review_id, review.review_date AS review_...
^
'SELECT review.id AS review_id, review.review_date AS review_review_date, review.review_comment AS review_review_comment, review.rating AS review_rating, review.course_id AS review_course_id, review.user_id AS review_user_id, count(review.course_id) AS count_1 \nFROM review GROUP BY review.course_id \nHAVING count(review.course_id) > %(count_2)s ORDER BY count(review.course_id) DESC' {'count_2': 1}
I tried to fix the query by adding models.Review in the GROUP BY clause but it did not work:
most_rated_courses = db.session.query(models.Review, func.count(models.Review.course_id)).group_by(models.Review.course_id).\
having(func.count(models.Review.course_id) >1) \.order_by(func.count(models.Review.course_id).desc()).all()
Can anyone please help me with this issue. Thanks a lot
SQLite and MySQL both have the behavior that they allow a query that has aggregates (like count()) without applying GROUP BY to all other columns - which in terms of standard SQL is invalid, because if more than one row is present in that aggregated group, it has to pick the first one it sees for return, which is essentially random.
So your query for Review basically returns to you the first "Review" row for each distinct course id - like for course id 3, if you had seven "Review" rows, it's just choosing an essentially random "Review" row within the group of "course_id=3". I gather the answer you really want, "Course", is available here because you can take that semi-randomly selected Review object and just call ".course" on it, giving you the correct Course, but this is a backwards way to go.
But once you get on a proper database like Postgresql you need to use correct SQL. The data you need from the "review" table is just the course_id and the count, nothing else, so query just for that (first assume we don't actually need to display the counts, that's in a minute):
most_rated_course_ids = session.query(
Review.course_id,
).\
group_by(Review.course_id).\
having(func.count(Review.course_id) > 1).\
order_by(func.count(Review.course_id).desc()).\
all()
but that's not your Course object - you want to take that list of ids and apply it to the course table. We first need to keep our list of course ids as a SQL construct, instead of loading the data - that is, turn it into a derived table by converting the query into a subquery (change the word .all() to .subquery()):
most_rated_course_id_subquery = session.query(
Review.course_id,
).\
group_by(Review.course_id).\
having(func.count(Review.course_id) > 1).\
order_by(func.count(Review.course_id).desc()).\
subquery()
one simple way to link that to Course is to use an IN:
courses = session.query(Course).filter(
Course.id.in_(most_rated_course_id_subquery)).all()
but that's essentially going to throw away the "ORDER BY" you're looking for and also doesn't give us any nice way of actually reporting on those counts along with the course results. We need to have that count along with our Course so that we can report it and also order by it. For this we use a JOIN from the "course" table to our derived table. SQLAlchemy is smart enough to know to join on the "course_id" foreign key if we just call join():
courses = session.query(Course).join(most_rated_course_id_subquery).all()
then to get at the count, we need to add that to the columns returned by our subquery along with a label so we can refer to it:
most_rated_course_id_subquery = session.query(
Review.course_id,
func.count(Review.course_id).label("count")
).\
group_by(Review.course_id).\
having(func.count(Review.course_id) > 1).\
subquery()
courses = session.query(
Course, most_rated_course_id_subquery.c.count
).join(
most_rated_course_id_subquery
).order_by(
most_rated_course_id_subquery.c.count.desc()
).all()
A great article I like to point out to people about GROUP BY and this kind of query is SQL GROUP BY techniques which points out the common need for the "select from A join to (subquery of B with aggregate/GROUP BY)" pattern.
This might be a very simple thing. Check out the normal sql query below
(select * from shopping order by shopping_id desc limit 5) order by RAND()
This query runs successfully in mysql - not sure if this is the right way of doing it - but it works. It gets the last 5 ids from shopping table and randomly orders them everytime
I want to achieve this in Zend. I'm not sure how to execute the first part and then apply the RAND clause to the results - what I have below does not do that.
$select = $this->select()
->from(array('sh'=>'shopping'))
->order('shopping_id desc')
->limit(5)
->order('RAND()');
Why not take a slightly different approach which will acheive the same results. If you drop the subselect and the order by RAND() you can get the rows very quickly from the database, then when you are working with the rows, you could always randomize them.
$select = $this->select()
->from(array('sh'=>'shopping'))
->order('shopping_id desc')
->limit(5)
$rows = $this->fetchAll($select);
// take it from a rowset object, convert to an array:
$rowArray = array();
foreach ($rows as $row) $rowArray[] = $row;
shuffle($rowArray);
The Zend_Db_Expr class lets you do that. You create a new instance of the Zend_Db_Expr class and using its constructor you pass in the expression as a string: "RANDOM()".
$select = $this->select()
->from(array('sh'=>'shopping'))
->order('shopping_id desc')
->limit(5)
->order(new Zend_Db_Expr('RANDOM()'));
I'm working on an Active Record pattern (similar to RoR/Cake) for my Zend Framework library. My question is this: How do I figure out whether a select object is using an alias for a table or not?
$select->from(array("c" => "categories"));
vs.
$select->from("categories");
and I pass this to a "fetch" function which adds additional joins and whatnot to get the row relationships automatically...I want to add some custom sql; either "c.id" or "categories.id" based on how the user used the "from" method.
I know I can use
$parts = $select->getPart(Zend_Db_Select::FROM);
to get the from data as an array, and the table name or alias seems to be in "slot" 0 of said array. Will the table name or alias always be in slot zero? i.e. can I reliably use:
$tableNameOrAlias = $parts[0];
Sorry if this is convolute but hope you can help! :)
Logically, I would think that's how it should work. To be on the safe side, build a few dummy queries using a Select() and dump the part array using print_r or such.
I just performed this test, the alias is the array key, it is not a zero-based numeric array:
$select = $this->db->select()->from(array("c" => "categories","d" => "dummies"));
$parts = $select->getPart(Zend_Db_Select::FROM);
echo '<pre>';
print_r($parts);
echo '</pre>';
Output:
Array
(
[c] => Array
(
[joinType] => inner join
[schema] =>
[tableName] => categories
[joinCondition] =>
)
)
So you would need to reference it as $part["c"]