revise readme
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Justin Kramer
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103
README.md
103
README.md
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@ -7,66 +7,107 @@ SQL as Clojure data structures.
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## Usage
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```clj
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(require '[honeysql.core :as sql :refer [select from where limit merge-select
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merge-where]])
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(require '[honeysql.core
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:as sql
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:refer [select from where join order-by offset limit
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modifiers merge-select merge-where]])
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```
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;; Everything is centered around maps representing SQL queries
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Everything is built on top of maps representing SQL queries:
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```clj
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(def sqlmap {:select [:a :b :c]
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:from [:foo]
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:where [:= :f.a "baz"]})
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```
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;; format-sql turns maps into clojure.java.jdbc-compatible, parameterized SQL
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`format-sql` turns maps into `clojure.java.jdbc`-compatible, parameterized SQL:
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```clj
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(sql/format sqlmap)
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=> ["SELECT a, b, c FROM foo WHERE (f.a = ?)" ["baz"]]
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```
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;; The sql function is a helper for building query maps
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(= sqlmap
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(sql/sql :select [:a :b :c]
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:from :foo
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:where [:= :f.a "baz"]))
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=> true
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There are helper functions to build SQL maps. They compose together nicely.
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;; You can also use clause-specific helper functions, if you prefer. They
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;; compose together nicely.
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(= sqlmap
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```clj
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(-> (select :a :b :c)
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(from :foo)
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(where [:= :f.a "baz"])))
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(where [:= :f.a "baz"]))
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```
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Order doesn't matter.
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```clj
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(= (-> (select :*) (from :foo))
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(-> (from :foo) (select :*)))
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=> true
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```
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;; Providing a map as the first argument to sql or clause helper functions will
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;; use that map as a base, with the new clauses replacing old ones
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(sql/format (sql/sql sqlmap :select :* :limit 10))
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=> ["SELECT * FROM foo WHERE (f.a = ?) LIMIT 10" ["baz"]]
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(sql/format (-> sqlmap (select :*) (limit 10)))
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=> ["SELECT * FROM foo WHERE (f.a = ?) LIMIT 10" ["baz"]]
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When using the vanilla helper functions, new clauses will replace old clauses.
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;; To add to clauses instead of replacing them, use merge-sql, or merge-select,
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;; merge-from, etc.
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```clj
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(-> sqlmap (select :*))
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=> {:from [:foo], :where [:= :f.a "baz"], :select (:*)}
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```
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To add to clauses instead of replacing them, use `merge-select`, `merge-where`, etc.
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```clj
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(sql/format
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(sql/merge-sql sqlmap :select [:d :e] :where [:> :b 10]))
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=> ["SELECT a, b, c, d, e FROM foo WHERE ((f.a = ?) AND (b > 10))" ["baz"]]
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(sql/format
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(-> sqlmap (merge-select :d :e) (merge-where [:> :b 10])))
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(-> sqlmap
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(merge-select :d :e)
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(merge-where [:> :b 10])))
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=> ["SELECT a, b, c, d, e FROM foo WHERE ((f.a = ?) AND (b > 10))" ["baz"]]
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```
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;; Queries can be nested
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Queries can be nested:
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```clj
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(sql/format
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(sql/sql :select :*
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:from :foo
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:where [:in :foo.a (sql/sql :select :a :from :bar)]))
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(sql/format
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(-> (select :*)
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(from :foo)
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(where [:in :foo.a (-> (select :a) (from :bar))])))
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=> ["SELECT * FROM foo WHERE (foo.a IN (SELECT a FROM bar))"]
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```
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;; There are helper functions and data literals for handling SQL function
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;; calls and raw SQL fragments
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(sql/sql :select [(sql/call :count :*) (sql/raw "@var := foo.bar")]
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:from :foo)
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There are helper functions and data literals for handling SQL function
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calls and raw SQL fragments:
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```clj
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(-> (select (sql/call :count :*) (sql/raw "@var := foo.bar"))
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(from :foo))
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=> {:from (:foo), :select (#sql/call [:count :*] #sql/raw "@var := foo.bar")}
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(sql/format *1)
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=> ["SELECT COUNT(*), @var := foo.bar FROM foo"]
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```
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Here's a complicated query:
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```clj
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(-> (select :f.* :b.baz :c.quux)
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(modifiers :distinct)
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(from [:foo :f] [:baz :b])
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(join [[:clod :c] [:= :f.a :c.d] :left]
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[:draq [:= :f.b :draq.x]])
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(where [:or
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[:and [:= :f.a "bort"] [:not= :b.baz "gabba"]]
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[:in :f.e [1 2 3]]
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[:between :f.e 10 20]])
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(order-by [:b.baz :desc] :c.quux)
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(limit 50)
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(offset 10))
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(sql/format *1)
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=> ["SELECT DISTINCT f.*, b.baz, c.quux FROM foo AS f, baz AS b LEFT JOIN clod AS c ON (f.a = c.d) JOIN draq ON (f.b = draq.x) WHERE (((f.a = ?) AND (b.baz != ?)) OR (f.e IN (1, 2, 3)) OR f.e BETWEEN 10 AND 20) ORDER BY b.baz DESC, c.quux LIMIT 50 OFFSET 10"
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["bort" "gabba"]]
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```
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## License
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Copyright © 2012 Justin Kramer
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