honeysql/doc/clause-reference.md

SQL Clauses Supported

This section lists all the SQL clauses that HoneySQL supports out of the box, in the order that they are processed for formatting.

Clauses can be specified as keywords or symbols. Use - in the clause name where the formatted SQL would have a space (e.g., :left-join is formatted as LEFT JOIN).

Except as noted, these clauses apply to all the SQL dialects that HoneySQL supports.

nest

with, with-recursive

intersect, union, union-all, except, except-all

These all expect a sequence of SQL clauses, those clauses will be wrapped in parentheses, and the SQL keyword interspersed between those clauses.

user=> (sql/format '{union [{select (id,status) from (table-a)}
                            {select (id,(event status) from (table-b))}]})
["(SELECT id, status FROM table_a) UNION (SELECT id, event AS status, from, table_b)"]

select, select-distinct

:select expects a sequence of SQL entities (column names or expressions). Any of the SQL entities can be a pair of entity and alias. If you are selecting an expression, you would most often provide an alias for the expression, but it can be omitted as in the following:

user=> (sql/format '{select (id, ((* cost 2)), (event status))
                     from (table)})
["SELECT id, cost * ?, event AS status FROM table" 2]

With an alias on the expression:

user=> (sql/format {:select [:id, [[:* :cost 2] :total], [:event :status]]
                    :from [:table]})
["SELECT id, cost * ? AS total, event AS status FROM table" 2]

:select-distinct works the same way but produces SELECT DISTINCT.

HoneySQL does not yet support SELECT .. INTO .. or SELECT .. BULK COLLECT INTO ...

insert-into

There are two use cases with :insert-into. The first case takes just a simple SQL entity (the table name). The more complex case takes a pair of a SQL entity and a SQL query. In that second case, you can specify the columns by using a pair of the table name and a sequence of column names.

For the first case, you'll use the :values clause and you may use the :columns clause as well.

user=> (sql/format {:insert-into :transport
                    :values [[1 "Car"] [2 "Boat"] [3 "Bike"]]})
["INSERT INTO transport VALUES (?, ?), (?, ?), (?, ?)" 1 "Car" 2 "Boat" 3 "Bike"]
user=> (sql/format {:insert-into :transport
                    :columns [:id :name]
                    :values [[1 "Car"] [2 "Boat"] [3 "Bike"]]})
["INSERT INTO transport (id, name) VALUES (?, ?), (?, ?), (?, ?)" 1 "Car" 2 "Boat" 3 "Bike"]

The second case:

user=> (sql/format '{insert-into (transport {select (id, name) from (cars)})})
["INSERT INTO transport SELECT id, name FROM cars"]
user=> (sql/format '{insert-into ((transport (id, name)) {select (*) from (cars)})})
["INSERT INTO transport (id, name) SELECT * FROM cars"]

update

:update expects either a simple SQL entity (table name) or a pair of the table name and an alias:

user=> (sql/format {:update :transport
                    :set {:name "Yacht"}
                    :where [:= :id 2]})
["UPDATE transport SET name = ? WHERE id = ?" "Yacht" 2]

delete, delete-from

:delete-from is the simple use case here, accepting just a SQL entity (table name). :delete allows for deleting from multiple tables, accepting a sequence of either table names or aliases:

user=> (sql/format '{delete-from transport where (= id 1)})
["DELETE FROM transport WHERE id = ?" 1]
user=> (sql/format {:delete [:order :item]
                    :from [:order]
                    :join [:item [:= :order.item-id :item.id]]
                    :where [:= :item.id 42]})
["DELETE order, item FROM order INNER JOIN item ON order.item_id = item.id WHERE item.id = ?" 42]

truncate

:truncate accepts a simple SQL entity (table name):

user=> (sql/format '{truncate transport})
["TRUNCATE transport"]

columns

Wherever you need just a list of column names :columns accepts a sequence of SQL entities (names). We saw an example above with :insert-into.

set (ANSI)

:set accepts a hash map of SQL entities and the values that they should be assigned. This precedence -- between :columns and :from -- corresponds to ANSI SQL which is correct for most databases. The MySQL dialect that HoneySQL 2.0 supports has a different precedence (below).

user=> (sql/format {:update :order
                    :set {:line-count [:+ :line-count 1]}
                    :where [:= :item-id 42]})
["UPDATE order SET line_count = line_count + ? WHERE item_id = ?" 1 42]

from

:from accepts a single sequence argument that lists one or more SQL entities. Each entity can either be a simple table name (keyword or symbol) or a pair of a table name and an alias:

user=> (sql/format {:select [:username :name]
                    :from [:user :status]
                    :where [:and [:= :user.statusid :status.id]
                                 [:= :user.id 9]]})
["SELECT username, name FROM user, status WHERE (user.statusid = status.id) AND (user.id = ?)" 9]
user=> (sql/format {:select [:u.username :s.name]
                    :from [[:user :u] [:status :s]]
                    :where [:and [:= :u.statusid :s.id]
                                 [:= :u.id 9]]})
["SELECT u.username, s.name FROM user AS u, status AS s WHERE (u.statusid = s.id) AND (u.id = ?)" 9]

Note: the actual formatting of a :from clause is currently identical to the formatting of a :select clause.

using

:using accepts a single sequence argument that lists one or more SQL entities. Each entity can either be a simple table name (keyword or symbol) or a pair of a table name and an alias.

:using is intended to be used as a simple join with a :delete-from clause (see PostgreSQL DELETE statement for more detail).

Note: the actual formatting of a :using clause is currently identical to the formatting of a :select clause.

join, left-join, right-join, inner-join, outer-join, full-join

All these join clauses have the same structure: they accept a sequence of alternating SQL entities (table names) and conditions that specify how to perform the join. The table names can either be simple names or a pair of a table name and an alias:

user=> (sql/format {:select [:u.username :s.name]
                    :from [[:user :u]]
                    :join [[:status :s] [:= :u.statusid :s.id]]
                    :where [:= :s.id 2]})
["SELECT u.username, s.name FROM user AS u INNER JOIN status AS s ON u.statusid = s.id WHERE s.id = ?" 2]

An alternative to a join condition is a USING expression:

user=> (sql/format {:select [:t.ref :pp.code]
                    :from [[:transaction :t]]
                    :left-join [[:paypal-tx :pp]
                                [:using :id]]
                    :where [:= "settled" :pp.status]})
["SELECT t.ref, pp.code FROM transaction AS t LEFT JOIN paypal_tx AS pp USING (id) WHERE ? = pp.status" "settled"]

cross-join

:cross-join accepts a single sequence argument that lists one or more SQL entities. Each entity can either be a simple table name (keyword or symbol) or a pair of a table name and an alias.

Note: the actual formatting of a :cross-join clause is currently identical to the formatting of a :select clause.

set (MySQL)

This is the precedence of the :set clause for the MySQL dialect. It is otherwise identical to the :set clause described above.

where

The :where clause can have a single SQL expression, or a sequence of SQL expressions prefixed by either :and or :or. See examples of :where in various clauses above.

group-by

:group-by accepts a sequence of one or more SQL expressions.

user=> (sql/format '{select (*) from (table)
                     group-by (status, (year created-date))})
["SELECT * FROM table GROUP BY status, YEAR(created_date)"]

having

The :having clause works identically to :where above but is rendered into the SQL later in precedence order.

order-by

:order-by accepts a sequence of one or more ordering expressions. Each ordering expression is either a simple SQL entity or a pair of a SQL expression and a direction (which can be :asc or :desc -- or the symbol equivalent).

If you want to order by an expression, you should wrap it as a pair with a direction:

user=> (sql/format '{select (*) from table
                     ;; simple orderings:
                     order-by (status, created-date)})
["SELECT * FROM table ORDER BY status ASC, created_date ASC"]
user=> (sql/format '{select (*) from table
                     ;; explicit direction provided:
                     order-by ((status asc), ((year created-date) asc))})
["SELECT * FROM table ORDER BY status ASC, YEAR(created_date) ASC"]

The default direction is ascending and if you provide a wrapped expression you can omit the direction if you want:

user=> (sql/format {:select [:*] :from :table
                    ;; expression without direction is still wrapped:
                    :order-by [:status, [[:year :created-date]]]})
["SELECT * FROM table ORDER BY status ASC, YEAR(created_date) ASC"]

limit, offset (MySQL)

Both :limit and :offset expect a single SQL expression:

user=> (sql/format {:select [:id :name]
                    :from [:table]
                    :limit 20 :offset 20})
["SELECT id, name FROM table LIMIT ? OFFSET ?" 20 20]

Note: In the prerelease, these MySQL-specific clauses are in the default dialect but these will be moved to the :mysql dialect.

for

The :for clause accepts either a single item -- the lock strength -- or a sequence of up to three items of which the first is the lock strength, followed by an optional table name (or sequence of table names), followed by how to deal with the lock:

user=> (sql/format '{select (*) from (table)
                     for update})
["SELECT * FROM table FOR UPDATE"]
user=> (sql/format '{select (*) from (table)
                     for no-key-update})
["SELECT * FROM table FOR NO KEY UPDATE"]
user=> (sql/format '{select (*) from (table)
                     for (key-share wait)})
["SELECT * FROM table FOR KEY SHARE WAIT"]
user=> (sql/format '{select (*) from (table)
                     for (update bar wait)})
["SELECT * FROM table FOR UPDATE OF bar WAIT"]
user=> (sql/format '{select (*) from (table)
                     for (update (bar quux) wait)})
["SELECT * FROM table FOR UPDATE OF bar, quux WAIT"]

The lock strength can be any SQL keyword or phrase represented as a Clojure keyword (or symbol), with spaces represented by -.

The three SQL keywords/phrases that are recognized as not being a table name in the second slot are NOWAIT, SKIP LOCKED, and WAIT.

However, in the case where a table name (or sequence of table names) is present, no check is made on the keyword or phrase in that third slot (although it is expected to be just one of those three mentioned above).

lock (MySQL)

The syntax accepted for MySQL's :lock is exactly the same as the :for clause above.

Note: In the prerelease, this MySQL-specific clauses is in the default dialect but this will be moved to the :mysql dialect.

values

:values accepts either a sequence of hash maps representing row values or a sequence of sequences, also representing row values.

In the former case, all of the rows are augmented to have nil values for any missing keys (columns). In the latter, all of the rows are padded to the same length by adding nil values if needed.

user=> (sql/format {:insert-into :table
                    :values [[1 2] [2 3 4 5] [3 4 5]]})
["INSERT INTO table VALUES (?, ?, NULL, NULL), (?, ?, ?, ?), (?, ?, ?, NULL)" 1 2 2 3 4 5 3 4 5]
user=> (sql/format '{insert-into table
                     values ({id 1 name "Sean"}
                             {id 2}
                             {name "Extra"})})
["INSERT INTO table (id, name) VALUES (?, ?), (?, NULL), (NULL, ?)" 1 "Sean" 2 "Extra"]

on-conflict, on-constraint, do-nothing, do-update-set

These are grouped together because they are handled as if they are separate clauses but they will appear in pairs: ON ... DO ....

:on-conflict accepts either a single SQL entity (a keyword or symbol) or a SQL clause. That's either a column name or an :on-constraint clause or a :where clause.

:on-constraint accepts a single SQL entity that identifies a constraint name.

Since :do-nothing is a SQL clause but has no associated data, it still has to have an arbitrary value because clauses are hash maps and that value will be ignored so :do-nothing true is a reasonable choices.

:do-update-set accepts either a single SQL entity (a keyword or symbol) or hash map of columns and values, like :set (above). The former produces a SET clause using EXCLUDED:

user=> (sql/format {:insert-into :companies
                    :values [{:name "Microsoft"}]
                    :on-conflict :name
                    :do-update-set :name})
["INSERT INTO companies (name) VALUES (?) ON CONFLICT (name) DO UPDATE SET name = EXCLUDED.name" "Microsoft"]
user=> (sql/format {:insert-into :companies
                    :values [{:name "Microsoft"}]
                    :on-conflict {:on-constraint :name-idx}
                    :do-nothing true})
["INSERT INTO companies (name) VALUES (?) ON CONFLICT ON CONSTRAINT name_idx DO NOTHING" "Microsoft"]

returning

:returning accepts a single sequence argument that lists one or more SQL entities. Each entity can either be a simple table name (keyword or symbol) or a pair of a table name and an alias.

Note: the actual formatting of a :returning clause is currently identical to the formatting of a :select clause.