Joins Model definitions Performing simple joins Joining multiple tables Selecting from multiple sources Subqueries Multiple foreign-keys to the same Model Joining on arbitrary fields Self-joins Implementing . meow favorited 1 times hiss favorited 0 times purr favorited 2 times Selecting from multiple sources If we wished to list all the tweets in the database, along with the username of their author, you foreign-key for us. Note This technique is discussed in more detail in Selecting from multiple sources. List users and all their tweets Let’s say you want to build a page that shows several users and

meow favorited 1 times hiss favorited 0 times purr favorited 2 times 1.9.4 Selecting from multiple sources If we wished to list all the tweets in the database, along with the username of their author, you foreign-key for us. Note: This technique is discussed in more detail in Selecting from multiple sources. List users and all their tweets Let’s say you want to build a page that shows several users and distinct=None[, windows=None[, for_update=None[, **kwargs]]]]]]]]) Parameters • from_list (list) – List of sources for FROM clause. • columns (list) – Columns or values to select. • group_by (list) – List of columns

distinct=None[, windows=None[, for_update=None[, **kwargs]]]]]]]]) from_list (list) – List of sources for FROM clause. columns (list) – Columns or values to select. group_by (list) – List of columns SELECT. Same as Select.columns(), provided for backwards-compatibility. from_(*sources) sources – Zero or more sources for the FROM clause. Specify which table-like objects should be used in the FROM to create model instances. Note This method can be used, when selecting field data from multiple sources/models, to make all data available as attributes on the model being queried (as opposed to constructing

windows=None[, for_update=None[, **kwargs]]]]]]]]) Parameters: Parameters: from_list (list) – List of sources for FROM clause. columns (list) – Columns or values to select. group_by (list) – List of columns join(Tweet, JOIN.LEFT_OUTER) .group_by(User)) return query from_(*sources) sources – Zero or more sources for the FROM clause. Specify which table-like objects should be used in the FROM to create model instances. Note This method can be used, when selecting field data from multiple sources/models, to make all data available as attributes on the model being queried (as opposed to constructing

windows=None[, for_update=None[, **kwargs]]]]]]]]) Parameters: Parameters: from_list (list) – List of sources for FROM clause. columns (list) – Columns or values to select. group_by (list) – List of columns join(Tweet, JOIN.LEFT_OUTER) .group_by(User)) return query from_(*sources) sources – Zero or more sources for the FROM clause. Specify which table-like objects should be used in the FROM to create model instances. Note This method can be used, when selecting field data from multiple sources/models, to make all data available as attributes on the model being queried (as opposed to constructing

distinct=None[, windows=None[, for_update=None[, **kwargs]]]]]]]]) from_list (list) – List of sources for FROM clause. columns (list) – Columns or values to select. group_by (list) – List of columns join(Tweet, JOIN.LEFT_OUTER) .group_by(User)) return query from_(*sources) sources – Zero or more sources for the FROM clause. Specify which table-like objects should be used in the FROM to create model instances. Note This method can be used, when selecting field data from multiple sources/models, to make all data available as attributes on the model being queried (as opposed to constructing

distinct=None[, windows=None[, for_update=None[, **kwargs]]]]]]]]) Parameters • from_list (list) – List of sources for FROM clause. • columns (list) – Columns or values to select. • group_by (list) – List of columns alias('count')) .join(Tweet, JOIN.LEFT_OUTER) .group_by(User)) return query from_(*sources) Parameters sources – Zero or more sources for the FROM clause. Specify which table-like objects should be used in the create model instances. Note: This method can be used, when selecting field data from multiple sources/models, to make all data available as attributes on the model being queried (as opposed to constructing

distinct=None[, windows=None[, for_update=None[, **kwargs]]]]]]]]) Parameters • from_list (list) – List of sources for FROM clause. • columns (list) – Columns or values to select. • group_by (list) – List of columns alias('count')) .join(Tweet, JOIN.LEFT_OUTER) .group_by(User)) return query from_(*sources) Parameters sources – Zero or more sources for the FROM clause. Specify which table-like objects should be used in the create model instances. Note: This method can be used, when selecting field data from multiple sources/models, to make all data available as attributes on the model being queried (as opposed to constructing

distinct=None[, windows=None[, for_update=None[, **kwargs]]]]]]]]) Parameters • from_list (list) – List of sources for FROM clause. • columns (list) – Columns or values to select. • group_by (list) – List of columns alias('count')) .join(Tweet, JOIN.LEFT_OUTER) .group_by(User)) return query from_(*sources) Parameters sources – Zero or more sources for the FROM clause. Specify which table-like objects should be used in the create model instances. Note: This method can be used, when selecting field data from multiple sources/models, to make all data available as attributes on the model being queried (as opposed to constructing