From f45b5f9dc8e7074506753e32ce8ad408b1b62bc8 Mon Sep 17 00:00:00 2001 From: Jeff Cole Date: Sun, 28 Feb 2016 10:05:00 -0700 Subject: Clean up README code * Fixes syntax highlighting of the output from `SqlLiteral` * Adds whitespace to improve readability --- README.md | 92 +++++++++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 66 insertions(+), 26 deletions(-) (limited to 'README.md') diff --git a/README.md b/README.md index 48df6700c4..757b062898 100644 --- a/README.md +++ b/README.md @@ -56,24 +56,48 @@ users.project(users[:id]) Comparison operators `=`, `!=`, `<`, `>`, `<=`, `>=`, `IN`: ```ruby -users.where(users[:age].eq(10)).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE "users"."age" = 10 -users.where(users[:age].not_eq(10)).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE "users"."age" != 10 -users.where(users[:age].lt(10)).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE "users"."age" < 10 -users.where(users[:age].gt(10)).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE "users"."age" > 10 -users.where(users[:age].lteq(10)).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE "users"."age" <= 10 -users.where(users[:age].gteq(10)).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE "users"."age" >= 10 -users.where(users[:age].in([20, 16, 17])).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE "users"."age" IN (20, 16, 17) +users.where(users[:age].eq(10)).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE "users"."age" = 10 + +users.where(users[:age].not_eq(10)).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE "users"."age" != 10 + +users.where(users[:age].lt(10)).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE "users"."age" < 10 + +users.where(users[:age].gt(10)).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE "users"."age" > 10 + +users.where(users[:age].lteq(10)).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE "users"."age" <= 10 + +users.where(users[:age].gteq(10)).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE "users"."age" >= 10 + +users.where(users[:age].in([20, 16, 17])).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE "users"."age" IN (20, 16, 17) ``` Bitwise operators `&`, `|`, `^`, `<<`, `>>`: ```ruby -users.where((users[:bitmap] & 16).gt(0)).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE ("users"."bitmap" & 16) > 0 -users.where((users[:bitmap] | 16).gt(0)).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE ("users"."bitmap" | 16) > 0 -users.where((users[:bitmap] ^ 16).gt(0)).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE ("users"."bitmap" ^ 16) > 0 -users.where((users[:bitmap] << 1).gt(0)).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE ("users"."bitmap" << 1) > 0 -users.where((users[:bitmap] >> 1).gt(0)).project(Arel.sql('*')) # => SELECT * FROM "users" WHERE ("users"."bitmap" >> 1) > 0 -users.where((~ users[:bitmap]).gt(0)).project(Arel.sql('*')) # => SELECT FROM "users" WHERE ~ "users"."bitmap" > 0 +users.where((users[:bitmap] & 16).gt(0)).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE ("users"."bitmap" & 16) > 0 + +users.where((users[:bitmap] | 16).gt(0)).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE ("users"."bitmap" | 16) > 0 + +users.where((users[:bitmap] ^ 16).gt(0)).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE ("users"."bitmap" ^ 16) > 0 + +users.where((users[:bitmap] << 1).gt(0)).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE ("users"."bitmap" << 1) > 0 + +users.where((users[:bitmap] >> 1).gt(0)).project(Arel.sql('*')) +# => SELECT * FROM "users" WHERE ("users"."bitmap" >> 1) > 0 + +users.where((~ users[:bitmap]).gt(0)).project(Arel.sql('*')) +# => SELECT FROM "users" WHERE ~ "users"."bitmap" > 0 ``` Joins resemble SQL strongly: @@ -130,18 +154,30 @@ The `AND` operator behaves similarly. Aggregate functions `AVG`, `SUM`, `COUNT`, `MIN`, `MAX`, `HAVING`: ```ruby -photos.group(photos[:user_id]).having(photos[:id].count.gt(5)) # => SELECT FROM photos GROUP BY photos.user_id HAVING COUNT(photos.id) > 5 -users.project(users[:age].sum) # => SELECT SUM(users.age) FROM users -users.project(users[:age].average) # => SELECT AVG(users.age) FROM users -users.project(users[:age].maximum) # => SELECT MAX(users.age) FROM users -users.project(users[:age].minimum) # => SELECT MIN(users.age) FROM users -users.project(users[:age].count) # => SELECT COUNT(users.age) FROM users +photos.group(photos[:user_id]).having(photos[:id].count.gt(5)) +# => SELECT FROM photos GROUP BY photos.user_id HAVING COUNT(photos.id) > 5 + +users.project(users[:age].sum) +# => SELECT SUM(users.age) FROM users + +users.project(users[:age].average) +# => SELECT AVG(users.age) FROM users + +users.project(users[:age].maximum) +# => SELECT MAX(users.age) FROM users + +users.project(users[:age].minimum) +# => SELECT MIN(users.age) FROM users + +users.project(users[:age].count) +# => SELECT COUNT(users.age) FROM users ``` Aliasing Aggregate Functions: ```ruby -users.project(users[:age].average.as("mean_age")) # => SELECT AVG(users.age) AS mean_age FROM users +users.project(users[:age].average.as("mean_age")) +# => SELECT AVG(users.age) AS mean_age FROM users ``` ### The Crazy Features @@ -190,7 +226,8 @@ Joining a table to itself requires aliasing in SQL. This aliasing can be handled replies = comments.alias comments_with_replies = \ comments.join(replies).on(replies[:parent_id].eq(comments[:id])).where(comments[:id].eq(1)) -# => SELECT * FROM comments INNER JOIN comments AS comments_2 WHERE comments_2.parent_id = comments.id AND comments.id = 1 +# => SELECT * FROM comments INNER JOIN comments AS comments_2 +# WHERE comments_2.parent_id = comments.id AND comments.id = 1 ``` This will return the reply for the first comment. @@ -212,7 +249,9 @@ users. project(users[:id], cte_table[:click].sum). with(composed_cte) -# => WITH cte_table AS (SELECT FROM photos WHERE photos.created_at > '2014-05-02') SELECT users.id, SUM(cte_table.click) FROM users INNER JOIN cte_table ON users.id = cte_table.user_id +# => WITH cte_table AS (SELECT FROM photos WHERE photos.created_at > '2014-05-02') +# SELECT users.id, SUM(cte_table.click) +# FROM users INNER JOIN cte_table ON users.id = cte_table.user_id ``` When your query is too complex for `Arel`, you can use `Arel::SqlLiteral`: @@ -225,12 +264,13 @@ photo_clicks = Arel::Nodes::SqlLiteral.new(<<-SQL ELSE default_calculation END SQL ) + photos.project(photo_clicks.as("photo_clicks")) # => SELECT CASE WHEN condition1 THEN calculation1 - WHEN condition2 THEN calculation2 - WHEN condition3 THEN calculation3 - ELSE default_calculation END - FROM "photos" +# WHEN condition2 THEN calculation2 +# WHEN condition3 THEN calculation3 +# ELSE default_calculation END +# FROM "photos" ``` ## Contributing to Arel -- cgit v1.2.3