Documentation (0.9)

Query Builder

Query Builder

Introduction

The database query builder provides a fluent interface to create and run database queries. It can be used to perform most database operations in your application, and works on all supported database systems.

Note

Since Orator uses DBAPI packages under the hood, there is no need to clean parameters passed as bindings.

Note

The underlying DBAPI connections are automatically configured to return dictionaries rather than the default tuple representation.

New in version 0.9: The returned rows also supports accessing the column values by attribute:

user = db.table('users').first()

name = user['name']
# is equivalent to
name = user.name

Changed in version 0.9: The returned rows will now be Collections to be more consistent with the behavior of the ORM.

Selects

Retrieving all row from a table

users = db.table('users').get()

for user in users:
    print(user['name'])

Chunking results from a table

for users in db.table('users').chunk(100):
    for user in users:
        # ...

Retrieving a single row from a table

user = db.table('users').where('name', 'John').first()
print(user['name'])

Retrieving a single column from a row

user = db.table('users').where('name', 'John').pluck('name')

Retrieving a list of column values

roles = db.table('roles').lists('title')

This method will return a list of role titles. It can return a dictionary if you pass an extra key parameter.

roles = db.table('roles').lists('title', 'name')

Specifying a select clause

users = db.table('users').select('name', 'email').get()

users = db.table('users').distinct().get()

users = db.table('users').select('name as user_name').get()

Adding a select clause to an existing query

query = db.table('users').select('name')

users = query.add_select('age').get()

Using where operators

users = db.table('users').where('age', '>', 25).get()

Or statements

users = db.table('users').where('age', '>', 25).or_where('name', 'John').get()

Using Where Between

users = db.table('users').where_between('age', [25, 35]).get()

Using Where Not Between

users = db.table('users').where_not_between('age', [25, 35]).get()

Using Where In

users = db.table('users').where_in('id', [1, 2, 3]).get()

users = db.table('users').where_not_in('id', [1, 2, 3]).get()

Using Where Null to find records with null values

users = db.table('users').where_null('updated_at').get()

Order by, group by and having

query = db.table('users').order_by('name', 'desc')
query = query.group_by('count')
query = query.having('count', '>', 100)

users = query.get()

Offset and limit

users = db.table('users').skip(10).take(5).get()

users = db.table('users').offset(10).limit(5).get()

Joins

The query builder can also be used to write join statements.

Basic join statement

db.table('users') \
    .join('contacts', 'users.id', '=', 'contacts.user_id') \
    .join('orders', 'users.id', '=', 'orders.user_id') \
    .select('users.id', 'contacts.phone', 'orders.price') \
    .get()

Left join statement

db.table('users').left_join('posts', 'users.id', '=', 'posts.user_id').get()

You can also specify more advance join clauses:

clause = JoinClause('contacts').on('users.id', '=', 'contacts.user_id').or_on(...)

db.table('users').join(clause).get()

If you would like to use a “where” style clause on your joins, you may use the where and orWhere methods on a join. Instead of comparing two columns, these methods will compare the column against a value:

clause = JoinClause('contacts').on('users.id', '=', 'contacts.user_id').where('contacts.user_id', '>', 5)

db.table('users').join(clause).get()

Advanced where

Sometimes you may need to create more advanced where clauses such as “where exists” or nested parameter groupings. It is pretty easy to do with the Orator query builder

Parameter grouping

db.table('users') \
    .where('name', '=', 'John') \
    .or_where(
        db.query().where('votes', '>', 100).where('title', '!=', 'admin')
    ).get()

The query above will produce the following SQL:

SELECT * FROM users WHERE name = 'John' OR (votes > 100 AND title != 'Admin')

Exists statement

db.table('users').where_exists(
    db.table('orders').select(db.raw(1)).where_raw('order.user_id = users.id')
)

The query above will produce the following SQL:

SELECT * FROM users
WHERE EXISTS (
    SELECT 1 FROM orders WHERE orders.user_id = users.id
)

Aggregates

The query builder also provides a variety of aggregate methods, ` such as count, max, min, avg, and sum.

users = db.table('users').count()

price = db.table('orders').max('price')

price = db.table('orders').min('price')

price = db.table('orders').avg('price')

total = db.table('users').sum('votes')

Raw expressions

Sometimes you may need to use a raw expression in a query. These expressions will be injected into the query as strings, so be careful not to create any SQL injection points! To create a raw expression, you may use the raw() method:

db.table('users') \
    .select(db.raw('count(*) as user_count, status')) \
    .where('status', '!=', 1) \
    .group_by('status') \
    .get()

Inserts

Insert records into a table

db.table('users').insert(email='foo@bar.com', votes=0)

db.table('users').insert({
    'email': 'foo@bar.com',
    'votes': 0
})

Note

It is important to note that there is two notations available. The reason is quite simple: the dictionary notation, though a little less practical, is here to handle columns names which cannot be passed as keywords arguments.

Inserting records into a table with an auto-incrementing ID

If the table has an auto-incrementing id, use insert_get_id to insert a record and retrieve the id:

id = db.table('users').insert_get_id({
    'email': 'foo@bar.com',
    'votes': 0
})

Inserting multiple record into a table

db.table('users').insert([
    {'email': 'foo@bar.com', 'votes': 0},
    {'email': 'bar@baz.com', 'votes': 0}
])

Updates

Updating records

db.table('users').where('id', 1).update(votes=1)

db.table('users').where('id', 1).update({'votes': 1})

Note

Like the insert statement, there is two notations available. The reason is quite simple: the dictionary notation, though a little less practical, is here to handle columns names which cannot be passed as keywords arguments.

Incrementing or decrementing the value of a column

db.table('users').increment('votes')  # Increment the value by 1

db.table('users').increment('votes', 5)  # Increment the value by 5

db.table('users').decrement('votes')  # Decrement the value by 1

db.table('users').decrement('votes', 5)  # Decrement the value by 5

You can also specify additional columns to update:

db.table('users').increment('votes', 1, name='John')

Deletes

Deleting records

db.table('users').where('age', '<', 25).delete()

Delete all records

db.table('users').delete()

Truncate

db.table('users').truncate()

Unions

The query builder provides a quick and easy way to “union” two queries:

first = db.table('users').where_null('first_name')

users = db.table('users').where_null('last_name').union(first).get()

The union_all method is also available.

Pessimistic locking

The query builder includes a few functions to help you do “pessimistic locking” on your SELECT statements.

To run the SELECT statement with a “shared lock”, you may use the shared_lock method on a query:

db.table('users').where('votes', '>', 100).shared_lock().get()

To “lock for update” on a SELECT statement, you may use the lock_for_update method on a query:

db.table('users').where('votes', '>', 100).lock_for_update().get()