What is PyPika?
PyPika is a Python API for building SQL queries. The motivation behind PyPika is to provide a simple interface for building SQL queries without limiting the flexibility of handwritten SQL. Designed with data analysis in mind, PyPika leverages the builder design pattern to construct queries to avoid messy string formatting and concatenation. It is also easily extended to take full advantage of specific features of SQL database vendors.
PyPika is a fast, expressive and flexible way to replace handwritten SQL (or even ORM for the courageous souls amongst you). Validation of SQL correctness is not an explicit goal of PyPika. With such a large number of SQL database vendors providing a robust validation of input data is difficult. Instead you are encouraged to check inputs you provide to PyPika or appropriately handle errors raised from your SQL database - just as you would have if you were writing SQL yourself.
Read the docs: http://pypika.readthedocs.io/en/latest/
PyPika supports python 3.6+. It may also work on pypy, cython, and jython, but is not being tested for these versions.
To install PyPika run the following command:
The main classes in pypika are pypika.Query, pypika.Table, and pypika.Field.
The entry point for building queries is pypika.Query. In order to select columns from a table, the table must first be added to the query. For simple queries with only one table, tables and columns can be references using strings. For more sophisticated queries a pypika.Table must be used.
To convert the query into raw SQL, it can be cast to a string.
Alternatively, you can use the Query.get_sql() function:
In simple queries like the above example, columns in the "from" table can be referenced by passing string names into the select query builder function. In more complex examples, the pypika.Table class should be used. Columns can be referenced as attributes on instances of pypika.Table.
Both of the above examples result in the following SQL:
An alias for the table can be given using the .as_ function on pypika.Table
A schema can also be specified. Tables can be referenced as attributes on the schema.
Also references to databases can be used. Schemas can be referenced as attributes on the database.
Results can be ordered by using the following syntax:
This results in the following SQL:
Arithmetic expressions can also be constructed using pypika. Operators such as +, -, *, and / are implemented by pypika.Field which can be used simply with a pypika.Table or directly.
Using pypika.Table
An alias can also be used for fields and expressions.
More arithmetic examples
Queries can be filtered with pypika.Criterion by using equality or inequality operators
Query methods such as select, where, groupby, and orderby can be called multiple times. Multiple calls to the where method will add additional conditions as
Filters such as IN and BETWEEN are also supported
Filtering with complex criteria can be created using boolean symbols &, |, and ^.
AND
OR
XOR
In the Criterion class, there are the static methods any and all that allow building chains AND and OR expressions with a list of terms.
Grouping allows for aggregated results and works similar to SELECT clauses.
After adding a GROUP BY clause to a query, the HAVING clause becomes available. The method Query.having() takes a Criterion parameter similar to the method Query.where().
Tables and subqueries can be joined to any query using the Query.join() method. Joins can be performed with either a USING or ON clauses. The USING clause can be used when both tables/subqueries contain the same field and the ON clause can be used with a criterion. To perform a join, ...join() can be chained but then must be followed immediately by ...on(<criterion>) or ...using(*field).
All join types are supported by PyPika.
See the list of join types here pypika.enums.JoinTypes
As a shortcut, the Query.join().on_field() function is provided for joining the (first) table in the FROM clause with the joined table when the field name(s) are the same in both tables.
history, customers = Tables('history', 'customers')
last_purchase_at = Query.from_(history).select(
history.purchase_at
).where(history.customer_id==customers.customer_id).orderby(
history.purchase_at, order=Order.desc
).limit(1)
q = Query.from_(customers).select(
customers.id, last_purchase_at.as_('last_purchase_at')
)Both UNION and UNION ALL are supported. UNION DISTINCT is synonymous with "UNIONso |Brand| does not provide a separate function for it. Unions require that queries have the same number ofSELECTclauses so trying to cast a unioned query to string will throw aSetOperationExceptionif the column sizes are mismatched. To create a union query, use either theQuery.union()method or `+` operator with two query instances. For a union all, useQuery.union_all()or the `*` operator. .. code-block:: python provider_a, provider_b = Tables('provider_a', 'provider_b') q = Query.from_(provider_a).select( provider_a.created_time, provider_a.foo, provider_a.bar ) + Query.from_(provider_b).select( provider_b.created_time, provider_b.fiz, provider_b.buz ) .. code-block:: sql SELECT "created_time","foo","bar" FROM "provider_a" UNION SELECT "created_time","fiz","buz" FROM "provider_b" Intersect """""""""INTERSECTis supported. Intersects require that queries have the same number ofSELECTclauses so trying to cast a intersected query to string will throw aSetOperationExceptionif the column sizes are mismatched. To create a intersect query, use theQuery.intersect()method. .. code-block:: python provider_a, provider_b = Tables('provider_a', 'provider_b') q = Query.from_(provider_a).select( provider_a.created_time, provider_a.foo, provider_a.bar ) r = Query.from_(provider_b).select( provider_b.created_time, provider_b.fiz, provider_b.buz ) intersected_query = q.intersect(r) .. code-block:: sql SELECT "created_time","foo","bar" FROM "provider_a" INTERSECT SELECT "created_time","fiz","buz" FROM "provider_b" Minus """""MINUSis supported. Minus require that queries have the same number ofSELECTclauses so trying to cast a minus query to string will throw aSetOperationExceptionif the column sizes are mismatched. To create a minus query, use either theQuery.minus()method or `-` operator with two query instances. .. code-block:: python provider_a, provider_b = Tables('provider_a', 'provider_b') q = Query.from_(provider_a).select( provider_a.created_time, provider_a.foo, provider_a.bar ) r = Query.from_(provider_b).select( provider_b.created_time, provider_b.fiz, provider_b.buz ) minus_query = q.minus(r) (or) minus_query = Query.from_(provider_a).select( provider_a.created_time, provider_a.foo, provider_a.bar ) - Query.from_(provider_b).select( provider_b.created_time, provider_b.fiz, provider_b.buz ) .. code-block:: sql SELECT "created_time","foo","bar" FROM "provider_a" MINUS SELECT "created_time","fiz","buz" FROM "provider_b" EXCEPT """"""EXCEPTis supported. Minus require that queries have the same number ofSELECTclauses so trying to cast a except query to string will throw aSetOperationExceptionif the column sizes are mismatched. To create a except query, use theQuery.except_of()method. .. code-block:: python provider_a, provider_b = Tables('provider_a', 'provider_b') q = Query.from_(provider_a).select( provider_a.created_time, provider_a.foo, provider_a.bar ) r = Query.from_(provider_b).select( provider_b.created_time, provider_b.fiz, provider_b.buz ) minus_query = q.except_of(r) .. code-block:: sql SELECT "created_time","foo","bar" FROM "provider_a" EXCEPT SELECT "created_time","fiz","buz" FROM "provider_b" Date, Time, and Intervals """"""""""""""""""""""""" Usingpypika.Interval, queries can be constructed with date arithmetic. Any combination of intervals can be used except for weeks and quarters, which must be used separately and will ignore any other values if selected. .. code-block:: python from pypika import functions as fn fruits = Tables('fruits') q = Query.from_(fruits) \ .select(fruits.id, fruits.name) \ .where(fruits.harvest_date + Interval(months=1) < fn.Now()) .. code-block:: sql SELECT id,name FROM fruits WHERE harvest_date+INTERVAL 1 MONTH<NOW() Tuples """""" Tuples are supported through the classpypika.Tuplebut also through the native python tuple wherever possible. Tuples can be used withpypika.Criterionin **WHERE** clauses for pairwise comparisons. .. code-block:: python from pypika import Query, Tuple q = Query.from_(self.table_abc) \ .select(self.table_abc.foo, self.table_abc.bar) \ .where(Tuple(self.table_abc.foo, self.table_abc.bar) == Tuple(1, 2)) .. code-block:: sql SELECT "foo","bar" FROM "abc" WHERE ("foo","bar")=(1,2) Usingpypika.Tupleon both sides of the comparison is redundant and |Brand| supports native python tuples. .. code-block:: python from pypika import Query, Tuple q = Query.from_(self.table_abc) \ .select(self.table_abc.foo, self.table_abc.bar) \ .where(Tuple(self.table_abc.foo, self.table_abc.bar) == (1, 2)) .. code-block:: sql SELECT "foo","bar" FROM "abc" WHERE ("foo","bar")=(1,2) Tuples can be used in **IN** clauses. .. code-block:: python Query.from_(self.table_abc) \ .select(self.table_abc.foo, self.table_abc.bar) \ .where(Tuple(self.table_abc.foo, self.table_abc.bar).isin([(1, 1), (2, 2), (3, 3)])) .. code-block:: sql SELECT "foo","bar" FROM "abc" WHERE ("foo","bar") IN ((1,1),(2,2),(3,3)) Strings Functions """"""""""""""""" There are several string operations and function wrappers included in |Brand|. Function wrappers can be found in thepypika.functionspackage. In addition, `LIKE` and `REGEX` queries are supported as well. .. code-block:: python from pypika import functions as fn customers = Tables('customers') q = Query.from_(customers).select( customers.id, customers.fname, customers.lname, ).where( customers.lname.like('Mc%') ) .. code-block:: sql SELECT id,fname,lname FROM customers WHERE lname LIKE 'Mc%' .. code-block:: python from pypika import functions as fn customers = Tables('customers') q = Query.from_(customers).select( customers.id, customers.fname, customers.lname, ).where( customers.lname.regex(r'^[abc][a-zA-Z]+&') ) .. code-block:: sql SELECT id,fname,lname FROM customers WHERE lname REGEX '^[abc][a-zA-Z]+&'; .. code-block:: python from pypika import functions as fn customers = Tables('customers') q = Query.from_(customers).select( customers.id, fn.Concat(customers.fname, ' ', customers.lname).as_('full_name'), ) .. code-block:: sql SELECT id,CONCAT(fname, ' ', lname) full_name FROM customers Custom Functions """""""""""""""" Custom Functions allows us to use any function on queries, as some functions are not covered by PyPika as default, we can appeal to Custom functions. .. code-block:: python from pypika import CustomFunction customers = Tables('customers') DateDiff = CustomFunction('DATE_DIFF', ['interval', 'start_date', 'end_date']) q = Query.from_(customers).select( customers.id, customers.fname, customers.lname, DateDiff('day', customers.created_date, customers.updated_date) ) .. code-block:: sql SELECT id,fname,lname,DATE_DIFF('day',created_date,updated_date) FROM customers Case Statements """"""""""""""" Case statements allow fow a number of conditions to be checked sequentially and return a value for the first condition met or otherwise a default value. The Case object can be used to chain conditions together along with their output using thewhenmethod and to set the default value usingelse. .. code-block:: python from pypika import Case, functions as fn customers = Tables('customers') q = Query.from_(customers).select( customers.id, Case() .when(customers.fname == "Tom", "It was Tom") .when(customers.fname == "John", "It was John") .else_("It was someone else.").as_('who_was_it') ) .. code-block:: sql SELECT "id",CASE WHEN "fname"='Tom' THEN 'It was Tom' WHEN "fname"='John' THEN 'It was John' ELSE 'It was someone else.' END "who_was_it" FROM "customers" With Clause """"""""""""""" With clause allows give a sub-query block a name, which can be referenced in several places within the main SQL query. The SQL WITH clause is basically a drop-in replacement to the normal sub-query. .. code-block:: python from pypika import Table, AliasedQuery, Query customers = Table('customers') sub_query = (Query .from_(customers) .select('*')) test_query = (Query .with_(sub_query, "an_alias") .from_(AliasedQuery("an_alias")) .select('*')) You can use as much as `.with_()` as you want. .. code-block:: sql WITH an_alias AS (SELECT * FROM "customers") SELECT * FROM an_alias Inserting Data ^^^^^^^^^^^^^^ Data can be inserted into tables either by providing the values in the query or by selecting them through another query. By default, data can be inserted by providing values for all columns in the order that they are defined in the table. Insert with values """""""""""""""""" .. code-block:: python customers = Table('customers') q = Query.into(customers).insert(1, 'Jane', 'Doe', 'jane@example.com') .. code-block:: sql INSERT INTO customers VALUES (1,'Jane','Doe','jane@example.com') .. code-block:: python customers = Table('customers') q = customers.insert(1, 'Jane', 'Doe', 'jane@example.com') .. code-block:: sql INSERT INTO customers VALUES (1,'Jane','Doe','jane@example.com') Multiple rows of data can be inserted either by chaining theinsertfunction or passing multiple tuples as args. .. code-block:: python customers = Table('customers') q = Query.into(customers).insert(1, 'Jane', 'Doe', 'jane@example.com').insert(2, 'John', 'Doe', 'john@example.com') .. code-block:: python customers = Table('customers') q = Query.into(customers).insert((1, 'Jane', 'Doe', 'jane@example.com'), (2, 'John', 'Doe', 'john@example.com')) Insert with constraint violation handling """"""""""""""""""""""""""""""""""""""""" MySQL ~~~~~ .. code-block:: python customers = Table('customers') q = MySQLQuery.into(customers) \ .insert(1, 'Jane', 'Doe', 'jane@example.com') \ .on_duplicate_key_ignore()) .. code-block:: sql INSERT INTO `customers` VALUES (1,'Jane','Doe','jane@example.com') ON DUPLICATE KEY IGNORE .. code-block:: python customers = Table('customers') q = MySQLQuery.into(customers) \ .insert(1, 'Jane', 'Doe', 'jane@example.com') \ .on_duplicate_key_update(customers.email, Values(customers.email)) .. code-block:: sql INSERT INTO `customers` VALUES (1,'Jane','Doe','jane@example.com') ON DUPLICATE KEY UPDATE `email`=VALUES(`email`).on_duplicate_key_updateworks similar to.setfor updating rows, additionally it provides theValueswrapper to update to the value specified in theINSERTclause. PostgreSQL ~~~~~~~~~~ .. code-block:: python customers = Table('customers') q = PostgreSQLQuery.into(customers) \ .insert(1, 'Jane', 'Doe', 'jane@example.com') \ .on_conflict(customers.email) \ .do_nothing() .. code-block:: sql INSERT INTO "customers" VALUES (1,'Jane','Doe','jane@example.com') ON CONFLICT ("email") DO NOTHING .. code-block:: python customers = Table('customers') q = PostgreSQLQuery.into(customers) \ .insert(1, 'Jane', 'Doe', 'jane@example.com') \ .on_conflict(customers.email) \ .do_update(customers.email, 'bob@example.com') .. code-block:: sql INSERT INTO "customers" VALUES (1,'Jane','Doe','jane@example.com') ON CONFLICT ("email") DO UPDATE SET "email"='bob@example.com' Insert from a SELECT Sub-query """""""""""""""""""""""""""""" .. code-block:: sql INSERT INTO "customers" VALUES (1,'Jane','Doe','jane@example.com'),(2,'John','Doe','john@example.com') To specify the columns and the order, use thecolumnsfunction. .. code-block:: python customers = Table('customers') q = Query.into(customers).columns('id', 'fname', 'lname').insert(1, 'Jane', 'Doe') .. code-block:: sql INSERT INTO customers (id,fname,lname) VALUES (1,'Jane','Doe','jane@example.com') Inserting data with a query works the same as querying data with the additional call to theintomethod in the builder chain. .. code-block:: python customers, customers_backup = Tables('customers', 'customers_backup') q = Query.into(customers_backup).from_(customers).select('*') .. code-block:: sql INSERT INTO customers_backup SELECT * FROM customers .. code-block:: python customers, customers_backup = Tables('customers', 'customers_backup') q = Query.into(customers_backup).columns('id', 'fname', 'lname') .from_(customers).select(customers.id, customers.fname, customers.lname) .. code-block:: sql INSERT INTO customers_backup SELECT "id", "fname", "lname" FROM customers The syntax for joining tables is the same as when selecting data .. code-block:: python customers, orders, orders_backup = Tables('customers', 'orders', 'orders_backup') q = Query.into(orders_backup).columns('id', 'address', 'customer_fname', 'customer_lname') .from_(customers) .join(orders).on(orders.customer_id == customers.id) .select(orders.id, customers.fname, customers.lname) .. code-block:: sql INSERT INTO "orders_backup" ("id","address","customer_fname","customer_lname") SELECT "orders"."id","customers"."fname","customers"."lname" FROM "customers" JOIN "orders" ON "orders"."customer_id"="customers"."id" Updating Data ^^^^^^^^^^^^^^ PyPika allows update queries to be constructed with or without where clauses. .. code-block:: python customers = Table('customers') Query.update(customers).set(customers.last_login, '2017-01-01 10:00:00') Query.update(customers).set(customers.lname, 'smith').where(customers.id == 10) .. code-block:: sql UPDATE "customers" SET "last_login"='2017-01-01 10:00:00' UPDATE "customers" SET "lname"='smith' WHERE "id"=10 The syntax for joining tables is the same as when selecting data .. code-block:: python customers, profiles = Tables('customers', 'profiles') Query.update(customers) .join(profiles).on(profiles.customer_id == customers.id) .set(customers.lname, profiles.lname) .. code-block:: sql UPDATE "customers" JOIN "profiles" ON "profiles"."customer_id"="customers"."id" SET "customers"."lname"="profiles"."lname" Usingpypika.Tablealias to perform the update .. code-block:: python customers = Table('customers') customers.update() .set(customers.lname, 'smith') .where(customers.id == 10) .. code-block:: sql UPDATE "customers" SET "lname"='smith' WHERE "id"=10 Usinglimitfor performing update .. code-block:: python customers = Table('customers') customers.update() .set(customers.lname, 'smith') .limit(2) .. code-block:: sql UPDATE "customers" SET "lname"='smith' LIMIT 2 Parametrized Queries ^^^^^^^^^^^^^^^^^^^^ PyPika allows you to useParameter(str)term as a placeholder for parametrized queries. .. code-block:: python customers = Table('customers') q = Query.into(customers).columns('id', 'fname', 'lname') .insert(Parameter(':1'), Parameter(':2'), Parameter(':3')) .. code-block:: sql INSERT INTO customers (id,fname,lname) VALUES (:1,:2,:3) This allows you to build prepared statements, and/or avoid SQL-injection related risks. Due to the mix of syntax for parameters, depending on connector/driver, it is required that you specify the parameter token explicitly or use one of the specialized Parameter types per [PEP-0249](https://www.python.org/dev/peps/pep-0249/#paramstyle):QmarkParameter(),NumericParameter(int),NamedParameter(str),FormatParameter(),PyformatParameter(str)An example of some common SQL parameter styles used in Python drivers are: PostgreSQL:$numberOR%s+:name(depending on driver) MySQL:%sSQLite:?Vertica::nameOracle::number+:nameMSSQL:%(name)sOR:name+:number(depending on driver) You can find out what parameter style is needed for DBAPI compliant drivers here: https://www.python.org/dev/peps/pep-0249/#paramstyle or in the DB driver documentation. Temporal support ^^^^^^^^^^^^^^^^ Temporal criteria can be added to the tables. Select """""" Here is a select using system time. .. code-block:: python t = Table("abc") q = Query.from_(t.for_(SYSTEM_TIME.as_of('2020-01-01'))).select("*") This produces: .. code-block:: sql SELECT * FROM "abc" FOR SYSTEM_TIME AS OF '2020-01-01' You can also use between. .. code-block:: python t = Table("abc") q = Query.from_( t.for_(SYSTEM_TIME.between('2020-01-01', '2020-02-01')) ).select("*") This produces: .. code-block:: sql SELECT * FROM "abc" FOR SYSTEM_TIME BETWEEN '2020-01-01' AND '2020-02-01' You can also use a period range. .. code-block:: python t = Table("abc") q = Query.from_( t.for_(SYSTEM_TIME.from_to('2020-01-01', '2020-02-01')) ).select("*") This produces: .. code-block:: sql SELECT * FROM "abc" FOR SYSTEM_TIME FROM '2020-01-01' TO '2020-02-01' Finally you can select for all times: .. code-block:: python t = Table("abc") q = Query.from_(t.for_(SYSTEM_TIME.all_())).select("*") This produces: .. code-block:: sql SELECT * FROM "abc" FOR SYSTEM_TIME ALL A user defined period can also be used in the following manner. .. code-block:: python t = Table("abc") q = Query.from_( t.for_(t.valid_period.between('2020-01-01', '2020-02-01')) ).select("*") This produces: .. code-block:: sql SELECT * FROM "abc" FOR "valid_period" BETWEEN '2020-01-01' AND '2020-02-01' Joins """"" With joins, when the table object is used when specifying columns, it is important to use the table from which the temporal constraint was generated. This is because `Table("abc")` is not the same table as `Table("abc").for_(...)`. The following example demonstrates this. .. code-block:: python t0 = Table("abc").for_(SYSTEM_TIME.as_of('2020-01-01')) t1 = Table("efg").for_(SYSTEM_TIME.as_of('2020-01-01')) query = ( Query.from_(t0) .join(t1) .on(t0.foo == t1.bar) .select("*") ) This produces: .. code-block:: sql SELECT * FROM "abc" FOR SYSTEM_TIME AS OF '2020-01-01' JOIN "efg" FOR SYSTEM_TIME AS OF '2020-01-01' ON "abc"."foo"="efg"."bar" Update & Deletes """""""""""""""" An update can be written as follows: .. code-block:: python t = Table("abc") q = Query.update( t.for_portion( SYSTEM_TIME.from_to('2020-01-01', '2020-02-01') ) ).set("foo", "bar") This produces: .. code-block:: sql UPDATE "abc" FOR PORTION OF SYSTEM_TIME FROM '2020-01-01' TO '2020-02-01' SET "foo"='bar' Here is a delete: .. code-block:: python t = Table("abc") q = Query.from_( t.for_portion(t.valid_period.from_to('2020-01-01', '2020-02-01')) ).delete() This produces: .. code-block:: sql DELETE FROM "abc" FOR PORTION OF "valid_period" FROM '2020-01-01' TO '2020-02-01' Creating Tables ^^^^^^^^^^^^^^^ The entry point for creating tables ispypika.Query.create_table, which is used with the classpypika.Column. As with selecting data, first the table should be specified. This can be either a string or a `pypika.Table`. Then the columns, and constraints. Here's an example that demonstrates much of the functionality. .. code-block:: python stmt = Query \ .create_table("person") \ .columns( Column("id", "INT", nullable=False), Column("first_name", "VARCHAR(100)", nullable=False), Column("last_name", "VARCHAR(100)", nullable=False), Column("phone_number", "VARCHAR(20)", nullable=True), Column("status", "VARCHAR(20)", nullable=False, default=ValueWrapper("NEW")), Column("date_of_birth", "DATETIME")) \ .unique("last_name", "first_name") \ .primary_key("id") This produces: .. code-block:: sql CREATE TABLE "person" ( "id" INT NOT NULL, "first_name" VARCHAR(100) NOT NULL, "last_name" VARCHAR(100) NOT NULL, "phone_number" VARCHAR(20) NULL, "status" VARCHAR(20) NOT NULL DEFAULT 'NEW', "date_of_birth" DATETIME, UNIQUE ("last_name","first_name"), PRIMARY KEY ("id") ) There is also support for creating a table from a query. .. code-block:: python stmt = Query.create_table("names").as_select( Query.from_("person").select("last_name", "first_name") ) This produces: .. code-block:: sql CREATE TABLE "names" AS (SELECT "last_name","first_name" FROM "person") Managing Table Indices ^^^^^^^^^^^^^^^^^^^^^^ Create Indices """""""""""""""" The entry point for creating indices ispypika.Query.create_index. An index name (asstr) or apypika.terms.Indexa table (asstrorpypika.Table) and columns (aspypika.Column) must be specified. .. code-block:: python my_index = Index("my_index") person = Table("person") stmt = Query \ .create_index(my_index) \ .on(person) \ .columns(person.first_name, person.last_name) This produces: .. code-block:: sql CREATE INDEX my_index ON person (first_name, last_name) It is also possible to create a unique index .. code-block:: python my_index = Index("my_index") person = Table("person") stmt = Query \ .create_index(my_index) \ .on(person) \ .columns(person.first_name, person.last_name) \ .unique() This produces: .. code-block:: sql CREATE UNIQUE INDEX my_index ON person (first_name, last_name) It is also possible to create an index if it does not exist .. code-block:: python my_index = Index("my_index") person = Table("person") stmt = Query \ .create_index(my_index) \ .on(person) \ .columns(person.first_name, person.last_name) \ .if_not_exists() This produces: .. code-block:: sql CREATE INDEX IF NOT EXISTS my_index ON person (first_name, last_name) Drop Indices """""""""""""""" Then entry point for dropping indices ispypika.Query.drop_index. It takes eitherstrorpypika.terms.Indexas an argument. .. code-block:: python my_index = Index("my_index") stmt = Query.drop_index(my_index) This produces: .. code-block:: sql DROP INDEX my_index It is also possible to drop an index if it exists .. code-block:: python my_index = Index("my_index") stmt = Query.drop_index(my_index).if_exists() This produces: .. code-block:: sql DROP INDEX IF EXISTS my_index Chaining Functions ^^^^^^^^^^^^^^^^^^ TheQueryBuilder.pipe`` method gives a more readable alternative while chaining functions.
Or for a more concrete example:
from pypika import Field, Query, functions as fn
from pypika.queries import QueryBuilder
def filter_days(query: QueryBuilder, col, num_days: int) -> QueryBuilder:
if isinstance(col, str):
col = Field(col)
return query.where(col > fn.Now() - num_days)
def count_groups(query: QueryBuilder, *groups) -> QueryBuilder:
return query.groupby(*groups).select(*groups, fn.Count("*").as_("n_rows"))
base_query = Query.from_("table")
query = (
base_query
.pipe(filter_days, "date", num_days=7)
.pipe(count_groups, "col1", "col2")
)This produces:
We welcome community contributions to PyPika. Please see the contributing guide to more info.
Copyright 2020 KAYAK Germany, GmbH
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
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