SQL Clauses

using FunSQL:
    AGG, AS, ASC, DESC, FROM, FUN, GROUP, HAVING, ID, JOIN, LIMIT, LIT,
    NOTE, ORDER, PARTITION, SELECT, SORT, UNION, VALUES, VAR, WHERE,
    WINDOW, WITH, pack, render

The syntactic structure of a SQL query is represented as a tree of SQLClause objects. Different types of clauses are created by specialized constructors and connected using the chain (|>) operator.

c = FROM(:person) |>
    SELECT(:person_id, :year_of_birth)
#-> (…) |> SELECT(…)

Displaying a SQLClause object shows how it was constructed.

display(c)
#-> ID(:person) |> FROM() |> SELECT(ID(:person_id), ID(:year_of_birth))

A SQLClause object wraps a concrete clause object, which can be accessed using the indexing operator.

c[]
#-> ((…) |> SELECT(…))[]

display(c[])
#-> (ID(:person) |> FROM() |> SELECT(ID(:person_id), ID(:year_of_birth)))[]

To generate SQL, we use function render().

print(render(c))
#=>
SELECT
  "person_id",
  "year_of_birth"
FROM "person"
=#

SQL Literals

A SQL literal is created using a LIT() constructor.

c = LIT("SQL is fun!")
#-> LIT("SQL is fun!")

Values of certain Julia data types are automatically converted to SQL literals when they are used in the context of a SQL clause.

using Dates

c = SELECT(missing, true, 42, "SQL is fun!", Date(2000))

display(c)
#=>
SELECT(LIT(missing),
       LIT(true),
       LIT(42),
       LIT("SQL is fun!"),
       LIT(Dates.Date("2000-01-01")))
=#

print(render(c))
#=>
SELECT
  NULL,
  TRUE,
  42,
  'SQL is fun!',
  '2000-01-01'
=#

Some values may render differently depending on the dialect.

c = LIT(false)

print(render(c, dialect = :sqlserver))
#-> (1 = 0)

A quote character in a string literal is represented by a pair of quotes.

c = LIT("O'Hare")

print(render(c))
#-> 'O''Hare'

Some dialects use backslash to escape quote characters.

print(render(c, dialect = :spark))
#-> 'O\'Hare'

SQL Identifiers

A SQL identifier is created with ID() constructor.

c = ID(:person)
#-> ID(:person)

display(c)
#-> ID(:person)

print(render(c))
#-> "person"

Serialization of an identifier depends on the SQL dialect.

print(render(c, dialect = :sqlserver))
#-> [person]

A quote character in an identifier is properly escaped.

c = ID("year of \"birth\"")

print(render(c))
#-> "year of ""birth"""

A qualified identifier is created using the chain operator.

c = ID(:person) |> ID(:year_of_birth)
#-> (…) |> ID(:year_of_birth)

display(c)
#-> ID(:person) |> ID(:year_of_birth)

print(render(c))
#-> "person"."year_of_birth"

Symbols and pairs of symbols are automatically converted to SQL identifiers when they are used in the context of a SQL clause.

c = FROM(:p => :person) |> SELECT((:p, :person_id))
display(c)
#-> ID(:person) |> AS(:p) |> FROM() |> SELECT(ID(:p) |> ID(:person_id))

print(render(c))
#=>
SELECT "p"."person_id"
FROM "person" AS "p"
=#

SQL Variables

Placeholder parameters to a SQL query are created with VAR() constructor.

c = VAR(:YEAR)
#-> VAR(:YEAR)

display(c)
#-> VAR(:YEAR)

print(render(c))
#-> :YEAR

Rendering of a SQL parameter depends on the chosen dialect.

print(render(c, dialect = :sqlite))
#-> ?1

print(render(c, dialect = :postgresql))
#-> $1

print(render(c, dialect = :mysql))
#-> ?

Function pack() converts named parameters to a positional form.

c = FROM(:person) |>
    WHERE(FUN(:or, FUN("=", :gender_concept_id, VAR(:GENDER)),
                   FUN("=", :gender_source_concept_id, VAR(:GENDER)))) |>
    SELECT(:person_id)

sql = render(c, dialect = :sqlite)

print(sql)
#=>
SELECT "person_id"
FROM "person"
WHERE
  ("gender_concept_id" = ?1) OR
  ("gender_source_concept_id" = ?1)
=#

pack(sql, (GENDER = 8532,))
#-> Any[8532]

pack(sql, Dict(:GENDER => 8532))
#-> Any[8532]

pack(sql, Dict("GENDER" => 8532))
#-> Any[8532]

If the dialect does not support numbered parameters, pack() may need to duplicate parameter values.

sql = render(c, dialect = :mysql)

print(sql)
#=>
SELECT `person_id`
FROM `person`
WHERE
  (`gender_concept_id` = ?) OR
  (`gender_source_concept_id` = ?)
=#

pack(sql, (GENDER = 8532,))
#-> Any[8532, 8532]

SQL Functions and Operators

An application of a SQL function is created with FUN() constructor.

c = FUN(:concat, :city, ", ", :state)
#-> FUN("concat", …)

display(c)
#-> FUN("concat", ID(:city), LIT(", "), ID(:state))

print(render(c))
#-> concat("city", ', ', "state")

c = FUN(:now)
#-> FUN("now")

print(render(c))
#-> now()

FUN() with an empty name generates a comma-separated list of values.

c = FUN("", "60614", "60615")

print(render(c))
#-> ('60614', '60615')

A name that contains only symbol characters is considered an operator.

c = FUN("||", :city, ", ", :state)

print(render(c))
#-> ("city" || ', ' || "state")

To create an operator containing alphabetical characters, add a leading or a trailing space to its name.

c = FUN(" IS DISTINCT FROM ", :zip, missing)

print(render(c))
#-> ("zip" IS DISTINCT FROM NULL)

c = FUN(" IS DISTINCT FROM", :zip, missing)

print(render(c))
#-> ("zip" IS DISTINCT FROM NULL)

c = FUN(" COLLATE \"C\"", :zip)

print(render(c))
#-> ("zip" COLLATE "C")

c = FUN("DATE ", "2000-01-01")

print(render(c))
#-> (DATE '2000-01-01')

c = FUN("CURRENT_TIME ")

print(render(c))
#-> CURRENT_TIME

c = FUN(" CURRENT_TIME")

print(render(c))
#-> CURRENT_TIME

To create a SQL expression with irregular syntax, supply FUN() with a template string.

c = FUN("SUBSTRING(? FROM ? FOR ?)", :zip, 1, 3)

print(render(c))
#-> SUBSTRING("zip" FROM 1 FOR 3)

c = FUN("?::date", "2000-01-01")

print(render(c))
#-> '2000-01-01'::date

Write ?? to use ? in an operator name or a template.

c = FUN("??-", "(1,0)", "(0,0)")

print(render(c))
#-> ('(1,0)' ?- '(0,0)')

c = FUN("('(?,?)'::point ??| '(?,?)'::point)", 0, 1, 0, 0)

print(render(c))
#-> ('(0,1)'::point ?| '(0,0)'::point)

Some functions and operators have specialized serializers.

c = FUN(:and)

print(render(c))
#-> TRUE

c = FUN(:and, true)

print(render(c))
#-> TRUE

c = FUN(:and, true, false)

print(render(c))
#-> (TRUE AND FALSE)

c = FUN(:or)

print(render(c))
#-> FALSE

c = FUN(:or, true)

print(render(c))
#-> TRUE

c = FUN(:or, true, false)

print(render(c))
#-> (TRUE OR FALSE)

c = FUN(:not, true)

print(render(c))
#-> (NOT TRUE)

c = FUN(:concat, :city, ", ", :state)

print(render(c))
#-> concat("city", ', ', "state")

print(render(c, dialect = :sqlite))
#-> ("city" || ', ' || "state")

c = FUN(:in, :zip)

print(render(c))
#-> FALSE

c = FUN(:in, :zip, "60614", "60615")

print(render(c))
#-> ("zip" IN ('60614', '60615'))

c = SELECT(FUN(:in, "60615", FROM(:location) |> SELECT(:zip)))

print(render(c))
#=>
SELECT ('60615' IN (
  SELECT "zip"
  FROM "location"
))
=#

c = FUN(:not_in, :zip)

print(render(c))
#-> TRUE

c = FUN(:not_in, :zip, "60614", "60615")

print(render(c))
#-> ("zip" NOT IN ('60614', '60615'))

c = SELECT(FUN(:not_in, "60615", FROM(:location) |> SELECT(:zip)))

print(render(c))
#=>
SELECT ('60615' NOT IN (
  SELECT "zip"
  FROM "location"
))
=#

c = SELECT(FUN(:exists, FROM(:location) |>
                        WHERE(FUN("=", :zip, "60615")) |>
                        SELECT(missing)))

print(render(c))
#=>
SELECT (EXISTS (
  SELECT NULL
  FROM "location"
  WHERE ("zip" = '60615')
))
=#

c = SELECT(FUN(:not_exists, FROM(:location) |>
                            WHERE(FUN("=", :zip, "60615")) |>
                            SELECT(missing)))

print(render(c))
#=>
SELECT (NOT EXISTS (
  SELECT NULL
  FROM "location"
  WHERE ("zip" = '60615')
))
=#

c = FUN(:is_null, :zip)

print(render(c))
#-> ("zip" IS NULL)

c = FUN(:is_not_null, :zip)

print(render(c))
#-> ("zip" IS NOT NULL)

c = FUN(:like, :zip, "606%")

print(render(c))
#-> ("zip" LIKE '606%')

c = FUN(:not_like, :zip, "606%")

print(render(c))
#-> ("zip" NOT LIKE '606%')

c = FUN(:case, FUN("<", :year_of_birth, 1970), "boomer")

print(render(c))
#-> (CASE WHEN ("year_of_birth" < 1970) THEN 'boomer' END)

c = FUN(:case, FUN("<", :year_of_birth, 1970), "boomer", "millenial")

print(render(c))
#-> (CASE WHEN ("year_of_birth" < 1970) THEN 'boomer' ELSE 'millenial' END)

c = FUN(:cast, "2020-01-01", "DATE")

print(render(c))
#-> CAST('2020-01-01' AS DATE)

c = FUN(:extract, "YEAR", c)

print(render(c))
#-> EXTRACT(YEAR FROM CAST('2020-01-01' AS DATE))

c = FUN(:between, :year_of_birth, 1950, 2000)

print(render(c))
#-> ("year_of_birth" BETWEEN 1950 AND 2000)

c = FUN(:not_between, :year_of_birth, 1950, 2000)

print(render(c))
#-> ("year_of_birth" NOT BETWEEN 1950 AND 2000)

c = FUN(:current_date)

print(render(c))
#-> CURRENT_DATE

c = FUN(:current_date, 1)

print(render(c))
#-> CURRENT_DATE(1)

c = FUN(:current_timestamp)

print(render(c))
#-> CURRENT_TIMESTAMP

Aggregate Functions

Aggregate SQL functions have a specialized AGG() constructor.

c = AGG(:max, :year_of_birth)
#-> AGG("max", …)

display(c)
#-> AGG("max", ID(:year_of_birth))

print(render(c))
#-> max("year_of_birth")

Some well-known aggregate functions with irregular syntax are supported.

c = AGG(:count)
#-> AGG("count")

display(c)
#-> AGG("count")

print(render(c))
#-> count(*)

c = AGG(:count_distinct, :zip)

print(render(c))
#-> count(DISTINCT "zip")

Otherwise, a template name can be used.

c = AGG("string_agg(DISTINCT ?, ',' ORDER BY ?)", :zip, :zip)

print(render(c))
#-> string_agg(DISTINCT "zip", ',' ORDER BY "zip")

An aggregate function may have a FILTER modifier.

c = AGG(:count, filter = FUN(">", :year_of_birth, 1970))

display(c)
#-> AGG("count", filter = FUN(">", ID(:year_of_birth), LIT(1970)))

print(render(c))
#-> (count(*) FILTER (WHERE ("year_of_birth" > 1970)))

A window function can be created by adding an OVER modifier.

c = PARTITION(:year_of_birth, order_by = [:month_of_birth, :day_of_birth]) |>
    AGG("row_number")

display(c)
#=>
AGG("row_number",
    over = PARTITION(ID(:year_of_birth),
                     order_by = [ID(:month_of_birth), ID(:day_of_birth)]))
=#

print(render(c))
#-> (row_number() OVER (PARTITION BY "year_of_birth" ORDER BY "month_of_birth", "day_of_birth"))

c = AGG("row_number", over = :w)

print(render(c))
#-> (row_number() OVER ("w"))

The PARTITION clause may contain a frame specification including the frame mode, frame endpoints, and frame exclusion.

c = PARTITION(order_by = [:year_of_birth], frame = :groups)
#-> PARTITION(order_by = […], frame = :GROUPS)

print(render(c))
#-> ORDER BY "year_of_birth" GROUPS UNBOUNDED PRECEDING

c = PARTITION(order_by = [:year_of_birth], frame = (mode = :rows,))
#-> PARTITION(order_by = […], frame = :ROWS)

print(render(c))
#-> ORDER BY "year_of_birth" ROWS UNBOUNDED PRECEDING

c = PARTITION(order_by = [:year_of_birth], frame = (mode = :range, start = -1, finish = 1, exclude = :current_row))
#-> PARTITION(order_by = […], frame = (mode = :RANGE, start = -1, finish = 1, exclude = :CURRENT_ROW))

print(render(c))
#-> ORDER BY "year_of_birth" RANGE BETWEEN 1 PRECEDING AND 1 FOLLOWING EXCLUDE CURRENT ROW

c = PARTITION(order_by = [:year_of_birth], frame = (mode = :range, start = -Inf, finish = 0))

print(render(c))
#-> ORDER BY "year_of_birth" RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW

c = PARTITION(order_by = [:year_of_birth], frame = (mode = :range, start = 0, finish = Inf))

print(render(c))
#-> ORDER BY "year_of_birth" RANGE BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING

c = PARTITION(order_by = [:year_of_birth], frame = (mode = :range, exclude = :no_others))

print(render(c))
#-> ORDER BY "year_of_birth" RANGE UNBOUNDED PRECEDING EXCLUDE NO OTHERS

c = PARTITION(order_by = [:year_of_birth], frame = (mode = :range, exclude = :group))

print(render(c))
#-> ORDER BY "year_of_birth" RANGE UNBOUNDED PRECEDING EXCLUDE GROUP

c = PARTITION(order_by = [:year_of_birth], frame = (mode = :range, exclude = :ties))

print(render(c))
#-> ORDER BY "year_of_birth" RANGE UNBOUNDED PRECEDING EXCLUDE TIES

AS Clause

An AS clause is created with AS() constructor.

c = ID(:person) |> AS(:p)
#-> (…) |> AS(:p)

display(c)
#-> ID(:person) |> AS(:p)

print(render(c))
#-> "person" AS "p"

A pair expression is automatically converted to an AS clause.

c = FROM(:p => :person)
display(c)
#-> ID(:person) |> AS(:p) |> FROM()

print(render(c |> SELECT((:p, :person_id))))
#=>
SELECT "p"."person_id"
FROM "person" AS "p"
=#

FROM Clause

A FROM clause is created with FROM() constructor.

c = FROM(:person)
#-> (…) |> FROM()

display(c)
#-> ID(:person) |> FROM()

print(render(c |> SELECT(:person_id)))
#=>
SELECT "person_id"
FROM "person"
=#

SELECT Clause

A SELECT clause is created with SELECT() constructor. While in SQL, SELECT typically opens a query, in FunSQL, SELECT() should be placed at the end of a clause chain.

c = :person |> FROM() |> SELECT(:person_id, :year_of_birth)
#-> (…) |> SELECT(…)

display(c)
#-> ID(:person) |> FROM() |> SELECT(ID(:person_id), ID(:year_of_birth))

print(render(c))
#=>
SELECT
  "person_id",
  "year_of_birth"
FROM "person"
=#

The DISTINCT modifier can be added from the constructor.

c = FROM(:location) |> SELECT(distinct = true, :zip)
#-> (…) |> SELECT(…)

display(c)
#-> ID(:location) |> FROM() |> SELECT(distinct = true, ID(:zip))

print(render(c))
#=>
SELECT DISTINCT "zip"
FROM "location"
=#

A TOP modifier could be specified.

c = FROM(:person) |> SELECT(top = 1, :person_id)

display(c)
#-> ID(:person) |> FROM() |> SELECT(top = 1, ID(:person_id))

print(render(c))
#=>
SELECT TOP 1 "person_id"
FROM "person"
=#

c = FROM(:person) |>
    ORDER(:year_of_birth) |>
    SELECT(top = (limit = 1, with_ties = true), :person_id)

display(c)
#=>
ID(:person) |>
FROM() |>
ORDER(ID(:year_of_birth)) |>
SELECT(top = (limit = 1, with_ties = true), ID(:person_id))
=#

print(render(c))
#=>
SELECT TOP 1 WITH TIES "person_id"
FROM "person"
ORDER BY "year_of_birth"
=#

A SELECT clause with an empty list of arguments can be created explicitly.

c = SELECT(args = [])
#-> SELECT(…)

Rendering a nested SELECT clause adds parentheses around it.

c = :location |> FROM() |> SELECT(:state, :zip) |> FROM() |> SELECT(:zip)

print(render(c))
#=>
SELECT "zip"
FROM (
  SELECT
    "state",
    "zip"
  FROM "location"
)
=#

WHERE Clause

A WHERE clause is created with WHERE() constructor.

c = FROM(:person) |> WHERE(FUN(">", :year_of_birth, 2000))
#-> (…) |> WHERE(…)

display(c)
#-> ID(:person) |> FROM() |> WHERE(FUN(">", ID(:year_of_birth), LIT(2000)))

print(render(c |> SELECT(:person_id)))
#=>
SELECT "person_id"
FROM "person"
WHERE ("year_of_birth" > 2000)
=#

LIMIT Clause

A LIMIT/OFFSET (or OFFSET/FETCH) clause is created with LIMIT() constructor.

c = FROM(:person) |> LIMIT(10)
#-> (…) |> LIMIT(10)

display(c)
#-> ID(:person) |> FROM() |> LIMIT(10)

print(render(c |> SELECT(:person_id)))
#=>
SELECT "person_id"
FROM "person"
FETCH FIRST 10 ROWS ONLY
=#

Many SQL dialects represent LIMIT clause with a non-standard syntax.

print(render(c |> SELECT(:person_id), dialect = :mysql))
#=>
SELECT `person_id`
FROM `person`
LIMIT 10
=#

print(render(c |> SELECT(:person_id), dialect = :postgresql))
#=>
SELECT "person_id"
FROM "person"
LIMIT 10
=#

print(render(c |> SELECT(:person_id), dialect = :sqlite))
#=>
SELECT "person_id"
FROM "person"
LIMIT 10
=#

print(render(c |> SELECT(:person_id), dialect = :sqlserver))
#=>
SELECT TOP 10 [person_id]
FROM [person]
=#

Both limit (the number of rows) and offset (number of rows to skip) can be specified.

c = FROM(:person) |> LIMIT(100, 10) |> SELECT(:person_id)

display(c)
#-> ID(:person) |> FROM() |> LIMIT(100, 10) |> SELECT(ID(:person_id))

print(render(c))
#=>
SELECT "person_id"
FROM "person"
OFFSET 100 ROWS
FETCH NEXT 10 ROWS ONLY
=#

print(render(c, dialect = :mysql))
#=>
SELECT `person_id`
FROM `person`
LIMIT 100, 10
=#

print(render(c, dialect = :postgresql))
#=>
SELECT "person_id"
FROM "person"
LIMIT 10
OFFSET 100
=#

print(render(c, dialect = :sqlite))
#=>
SELECT "person_id"
FROM "person"
LIMIT 10
OFFSET 100
=#

print(render(c, dialect = :sqlserver))
#=>
SELECT [person_id]
FROM [person]
OFFSET 100 ROWS
FETCH NEXT 10 ROWS ONLY
=#

Alternatively, both limit and offset can be specified as a unit range.

c = FROM(:person) |> LIMIT(101:110)

print(render(c |> SELECT(:person_id)))
#=>
SELECT "person_id"
FROM "person"
OFFSET 100 ROWS
FETCH NEXT 10 ROWS ONLY
=#

It is possible to specify the offset without the limit.

c = FROM(:person) |> LIMIT(offset = 100) |> SELECT(:person_id)

display(c)
#-> ID(:person) |> FROM() |> LIMIT(100, nothing) |> SELECT(ID(:person_id))

print(render(c))
#=>
SELECT "person_id"
FROM "person"
OFFSET 100 ROWS
=#

print(render(c, dialect = :mysql))
#=>
SELECT `person_id`
FROM `person`
LIMIT 100, 18446744073709551615
=#

print(render(c, dialect = :postgresql))
#=>
SELECT "person_id"
FROM "person"
OFFSET 100
=#

print(render(c, dialect = :sqlite))
#=>
SELECT "person_id"
FROM "person"
LIMIT -1
OFFSET 100
=#

print(render(c, dialect = :sqlserver))
#=>
SELECT [person_id]
FROM [person]
OFFSET 100 ROWS
=#

It is possible to specify the limit with ties.

c = FROM(:person) |>
    ORDER(:year_of_birth) |>
    LIMIT(10, with_ties = true) |>
    SELECT(:person_id)

display(c)
#=>
ID(:person) |>
FROM() |>
ORDER(ID(:year_of_birth)) |>
LIMIT(10, with_ties = true) |>
SELECT(ID(:person_id))
=#

print(render(c))
#=>
SELECT "person_id"
FROM "person"
ORDER BY "year_of_birth"
FETCH FIRST 10 ROWS WITH TIES
=#

SQL Server prohibits ORDER BY without limiting in a nested query, so FunSQL automatically adds OFFSET 0 clause to the query.

c = FROM(:person) |>
    ORDER(:year_of_birth) |>
    SELECT(:person_id, :gender_concept_id) |>
    AS(:person) |>
    FROM() |>
    WHERE(FUN("=", :gender_concept_id, 8507)) |>
    SELECT(:person_id)

print(render(c, dialect = :sqlserver))
#=>
SELECT [person_id]
FROM (
  SELECT
    [person_id],
    [gender_concept_id]
  FROM [person]
  ORDER BY [year_of_birth]
  OFFSET 0 ROWS
) AS [person]
WHERE ([gender_concept_id] = 8507)
=#

JOIN Clause

A JOIN clause is created with JOIN() constructor.

c = FROM(:p => :person) |>
    JOIN(:l => :location, FUN("=", (:p, :location_id), (:l, :location_id)), left = true)
#-> (…) |> JOIN(…)

display(c)
#=>
ID(:person) |>
AS(:p) |>
FROM() |>
JOIN(ID(:location) |> AS(:l),
     FUN("=", ID(:p) |> ID(:location_id), ID(:l) |> ID(:location_id)),
     left = true)
=#

print(render(c |> SELECT((:p, :person_id), (:l, :state))))
#=>
SELECT
  "p"."person_id",
  "l"."state"
FROM "person" AS "p"
LEFT JOIN "location" AS "l" ON ("p"."location_id" = "l"."location_id")
=#

Different types of JOIN are supported.

c = FROM(:p => :person) |>
    JOIN(:op => :observation_period,
         on = FUN("=", (:p, :person_id), (:op, :person_id)))

display(c)
#=>
ID(:person) |>
AS(:p) |>
FROM() |>
JOIN(ID(:observation_period) |> AS(:op),
     FUN("=", ID(:p) |> ID(:person_id), ID(:op) |> ID(:person_id)))
=#

print(render(c |> SELECT((:p, :person_id), (:op, :observation_period_start_date))))
#=>
SELECT
  "p"."person_id",
  "op"."observation_period_start_date"
FROM "person" AS "p"
JOIN "observation_period" AS "op" ON ("p"."person_id" = "op"."person_id")
=#

c = FROM(:l => :location) |>
    JOIN(:cs => :care_site,
         on = FUN("=", (:l, :location_id), (:cs, :location_id)),
         right = true)

display(c)
#=>
ID(:location) |>
AS(:l) |>
FROM() |>
JOIN(ID(:care_site) |> AS(:cs),
     FUN("=", ID(:l) |> ID(:location_id), ID(:cs) |> ID(:location_id)),
     right = true)
=#

print(render(c |> SELECT((:cs, :care_site_name), (:l, :state))))
#=>
SELECT
  "cs"."care_site_name",
  "l"."state"
FROM "location" AS "l"
RIGHT JOIN "care_site" AS "cs" ON ("l"."location_id" = "cs"."location_id")
=#

c = FROM(:p => :person) |>
    JOIN(:pr => :provider,
         on = FUN("=", (:p, :provider_id), (:pr, :provider_id)),
         left = true,
         right = true)

display(c)
#=>
ID(:person) |>
AS(:p) |>
FROM() |>
JOIN(ID(:provider) |> AS(:pr),
     FUN("=", ID(:p) |> ID(:provider_id), ID(:pr) |> ID(:provider_id)),
     left = true,
     right = true)
=#

print(render(c |> SELECT((:p, :person_id), (:pr, :npi))))
#=>
SELECT
  "p"."person_id",
  "pr"."npi"
FROM "person" AS "p"
FULL JOIN "provider" AS "pr" ON ("p"."provider_id" = "pr"."provider_id")
=#

To render a CROSS JOIN, set the join condition to true.

c = FROM(:p1 => :person) |>
    JOIN(:p2 => :person,
         on = true)

print(render(c |> SELECT((:p1, :person_id), (:p2, :person_id))))
#=>
SELECT
  "p1"."person_id",
  "p2"."person_id"
FROM "person" AS "p1"
CROSS JOIN "person" AS "p2"
=#

A JOIN LATERAL clause can be created.

c = FROM(:p => :person) |>
    JOIN(:vo => FROM(:vo => :visit_occurrence) |>
                WHERE(FUN("=", (:p, :person_id), (:vo, :person_id))) |>
                ORDER((:vo, :visit_start_date) |> DESC()) |>
                LIMIT(1) |>
                SELECT((:vo, :visit_start_date)),
         on = true,
         left = true,
         lateral = true)

display(c)
#=>
ID(:person) |>
AS(:p) |>
FROM() |>
JOIN(ID(:visit_occurrence) |>
     AS(:vo) |>
     FROM() |>
     WHERE(FUN("=", ID(:p) |> ID(:person_id), ID(:vo) |> ID(:person_id))) |>
     ORDER(ID(:vo) |> ID(:visit_start_date) |> DESC()) |>
     LIMIT(1) |>
     SELECT(ID(:vo) |> ID(:visit_start_date)) |>
     AS(:vo),
     LIT(true),
     left = true,
     lateral = true)
=#

print(render(c |> SELECT((:p, :person_id), (:vo, :visit_start_date))))
#=>
SELECT
  "p"."person_id",
  "vo"."visit_start_date"
FROM "person" AS "p"
LEFT JOIN LATERAL (
  SELECT "vo"."visit_start_date"
  FROM "visit_occurrence" AS "vo"
  WHERE ("p"."person_id" = "vo"."person_id")
  ORDER BY "vo"."visit_start_date" DESC
  FETCH FIRST 1 ROW ONLY
) AS "vo" ON TRUE
=#

GROUP Clause

A GROUP BY clause is created with GROUP constructor.

c = FROM(:person) |> GROUP(:year_of_birth)
#-> (…) |> GROUP(…)

display(c)
#-> ID(:person) |> FROM() |> GROUP(ID(:year_of_birth))

print(render(c |> SELECT(:year_of_birth, AGG(:count))))
#=>
SELECT
  "year_of_birth",
  count(*)
FROM "person"
GROUP BY "year_of_birth"
=#

A GROUP constructor accepts an empty partition list, in which case, it is not rendered.

c = FROM(:person) |> GROUP()
#-> (…) |> GROUP()

print(render(c |> SELECT(AGG(:count))))
#=>
SELECT count(*)
FROM "person"
=#

HAVING Clause

A HAVING clause is created with HAVING() constructor.

c = FROM(:person) |>
    GROUP(:year_of_birth) |>
    HAVING(FUN(">", AGG(:count), 10))
#-> (…) |> HAVING(…)

display(c)
#=>
ID(:person) |>
FROM() |>
GROUP(ID(:year_of_birth)) |>
HAVING(FUN(">", AGG("count"), LIT(10)))
=#

print(render(c |> SELECT(:person_id)))
#=>
SELECT "person_id"
FROM "person"
GROUP BY "year_of_birth"
HAVING (count(*) > 10)
=#

ORDER Clause

An ORDER BY clause is created with ORDER constructor.

c = FROM(:person) |> ORDER(:year_of_birth)
#-> (…) |> ORDER(…)

display(c)
#-> ID(:person) |> FROM() |> ORDER(ID(:year_of_birth))

print(render(c |> SELECT(:person_id)))
#=>
SELECT "person_id"
FROM "person"
ORDER BY "year_of_birth"
=#

An ORDER constructor accepts an empty list, in which case, it is not rendered.

c = FROM(:person) |> ORDER()
#-> (…) |> ORDER()

print(render(c |> SELECT(:person_id)))
#=>
SELECT "person_id"
FROM "person"
=#

It is possible to specify ascending or descending order of the sort column.

c = FROM(:person) |>
    ORDER(:year_of_birth |> DESC(nulls = :first),
          :person_id |> ASC()) |>
    SELECT(:person_id)

display(c)
#=>
ID(:person) |>
FROM() |>
ORDER(ID(:year_of_birth) |> DESC(nulls = :NULLS_FIRST),
      ID(:person_id) |> ASC()) |>
SELECT(ID(:person_id))
=#

print(render(c))
#=>
SELECT "person_id"
FROM "person"
ORDER BY
  "year_of_birth" DESC NULLS FIRST,
  "person_id" ASC
=#

Instead of ASC and DESC, a generic SORT constructor can be used.

c = FROM(:person) |>
    ORDER(:year_of_birth |> SORT(:desc, nulls = :last),
          :person_id |> SORT(:asc)) |>
    SELECT(:person_id)

print(render(c))
#=>
SELECT "person_id"
FROM "person"
ORDER BY
  "year_of_birth" DESC NULLS LAST,
  "person_id" ASC
=#

UNION Clause.

UNION and UNION ALL clauses are created with UNION() constructor.

c = FROM(:measurement) |>
    SELECT(:person_id, :date => :measurement_date) |>
    UNION(all = true,
          FROM(:observation) |>
          SELECT(:person_id, :date => :observation_date))
#-> (…) |> UNION(all = true, …)

display(c)
#=>
ID(:measurement) |>
FROM() |>
SELECT(ID(:person_id), ID(:measurement_date) |> AS(:date)) |>
UNION(all = true,
      ID(:observation) |>
      FROM() |>
      SELECT(ID(:person_id), ID(:observation_date) |> AS(:date)))
=#

print(render(c))
#=>
SELECT
  "person_id",
  "measurement_date" AS "date"
FROM "measurement"
UNION ALL
SELECT
  "person_id",
  "observation_date" AS "date"
FROM "observation"
=#

A UNION clause with no subqueries can be created explicitly.

UNION(args = [])
#-> UNION(args = [])

Rendering a nested UNION clause adds parentheses around it.

c = FROM(:measurement) |>
    SELECT(:person_id, :date => :measurement_date) |>
    UNION(all = true,
          FROM(:observation) |>
          SELECT(:person_id, :date => :observation_date)) |>
    FROM() |>
    AS(:union) |>
    WHERE(FUN(">", ID(:date), Date(2000))) |>
    SELECT(ID(:person_id))

print(render(c))
#=>
SELECT "person_id"
FROM (
  SELECT
    "person_id",
    "measurement_date" AS "date"
  FROM "measurement"
  UNION ALL
  SELECT
    "person_id",
    "observation_date" AS "date"
  FROM "observation"
) AS "union"
WHERE ("date" > '2000-01-01')
=#

VALUES Clause

A VALUES clause is created with VALUES() constructor.

c = VALUES([("SQL", 1974), ("Julia", 2012), ("FunSQL", 2021)])
#-> VALUES([("SQL", 1974), ("Julia", 2012), ("FunSQL", 2021)])

display(c)
#-> VALUES([("SQL", 1974), ("Julia", 2012), ("FunSQL", 2021)])

print(render(c))
#=>
VALUES
  ('SQL', 1974),
  ('Julia', 2012),
  ('FunSQL', 2021)
=#

MySQL has special syntax for rows.

print(render(c, dialect = :mysql))
#=>
VALUES
  ROW('SQL', 1974),
  ROW('Julia', 2012),
  ROW('FunSQL', 2021)
=#

When VALUES clause contains a single row, it is emitted on the same line.

c = VALUES([("SQL", 1974)])

print(render(c))
#-> VALUES ('SQL', 1974)

VALUES accepts a vector of scalar values.

c = VALUES(["SQL", "Julia", "FunSQL"])

print(render(c))
#=>
VALUES
  'SQL',
  'Julia',
  'FunSQL'
=#

When VALUES is nested in a FROM clause, it is wrapped in parentheses.

c = VALUES([("SQL", 1974), ("Julia", 2012), ("FunSQL", 2021)]) |>
    AS(:values, columns = [:name, :year]) |>
    FROM() |>
    SELECT(FUN("*"))

print(render(c))
#=>
SELECT *
FROM (
  VALUES
    ('SQL', 1974),
    ('Julia', 2012),
    ('FunSQL', 2021)
) AS "values" ("name", "year")
=#

WINDOW Clause

A WINDOW clause is created with WINDOW() constructor.

c = FROM(:person) |>
    WINDOW(:w1 => PARTITION(:gender_concept_id),
           :w2 => :w1 |> PARTITION(:year_of_birth, order_by = [:month_of_birth, :day_of_birth]))
#-> (…) |> WINDOW(…)

display(c)
#=>
ID(:person) |>
FROM() |>
WINDOW(PARTITION(ID(:gender_concept_id)) |> AS(:w1),
       ID(:w1) |>
       PARTITION(ID(:year_of_birth),
                 order_by = [ID(:month_of_birth), ID(:day_of_birth)]) |>
       AS(:w2))
=#

print(render(c |> SELECT(:w1 |> AGG("row_number"), :w2 |> AGG("row_number"))))
#=>
SELECT
  (row_number() OVER ("w1")),
  (row_number() OVER ("w2"))
FROM "person"
WINDOW
  "w1" AS (PARTITION BY "gender_concept_id"),
  "w2" AS ("w1" PARTITION BY "year_of_birth" ORDER BY "month_of_birth", "day_of_birth")
=#

The WINDOW() constructor accepts an empty list of partitions, in which case, it is not rendered.

c = FROM(:person) |>
    WINDOW(args = [])

display(c)
#-> ID(:person) |> FROM() |> WINDOW(args = [])

print(render(c |> SELECT(AGG("row_number", over = PARTITION()))))
#=>
SELECT (row_number() OVER ())
FROM "person"
=#

WITH Clause and Common Table Expressions

The AS clause that defines a common table expression is created using the AS constructor.

cte1 =
    FROM(:concept) |>
    WHERE(FUN("=", :concept_id, 320128)) |>
    SELECT(:concept_id, :concept_name) |>
    AS(:essential_hypertension)
#-> (…) |> AS(:essential_hypertension)

cte2 =
    FROM(:essential_hypertension) |>
    SELECT(:concept_id, :concept_name) |>
    UNION(all = true,
          FROM(:eh => :essential_hypertension_with_descendants) |>
          JOIN(:cr => :concept_relationship,
               FUN("=", (:eh, :concept_id), (:cr, :concept_id_1))) |>
          JOIN(:c => :concept,
               FUN("=", (:cr, :concept_id_2), (:c, :concept_id))) |>
          WHERE(FUN("=", (:cr, :relationship_id), "Subsumes")) |>
          SELECT((:c, :concept_id), (:c, :concept_name))) |>
    AS(:essential_hypertension_with_descendants,
        columns = [:concept_id, :concept_name])
#-> (…) |> AS(:essential_hypertension_with_descendants, columns = […])

The WITH clause is created using the WITH() constructor.

c = FROM(:essential_hypertension_with_descendants) |>
    SELECT(*) |>
    WITH(recursive = true, cte1, cte2)
#-> (…) |> WITH(recursive = true, …)

display(c)
#=>
ID(:essential_hypertension_with_descendants) |>
FROM() |>
SELECT(FUN("*")) |>
WITH(recursive = true,
     ID(:concept) |>
     FROM() |>
     WHERE(FUN("=", ID(:concept_id), LIT(320128))) |>
     SELECT(ID(:concept_id), ID(:concept_name)) |>
     AS(:essential_hypertension),
     ID(:essential_hypertension) |>
     FROM() |>
     SELECT(ID(:concept_id), ID(:concept_name)) |>
     UNION(all = true,
           ID(:essential_hypertension_with_descendants) |>
           AS(:eh) |>
           FROM() |>
           JOIN(ID(:concept_relationship) |> AS(:cr),
                FUN("=",
                    ID(:eh) |> ID(:concept_id),
                    ID(:cr) |> ID(:concept_id_1))) |>
           JOIN(ID(:concept) |> AS(:c),
                FUN("=",
                    ID(:cr) |> ID(:concept_id_2),
                    ID(:c) |> ID(:concept_id))) |>
           WHERE(FUN("=", ID(:cr) |> ID(:relationship_id), LIT("Subsumes"))) |>
           SELECT(ID(:c) |> ID(:concept_id), ID(:c) |> ID(:concept_name))) |>
     AS(:essential_hypertension_with_descendants,
        columns = [:concept_id, :concept_name]))
=#

print(render(c))
#=>
WITH RECURSIVE "essential_hypertension" AS (
  SELECT
    "concept_id",
    "concept_name"
  FROM "concept"
  WHERE ("concept_id" = 320128)
),
"essential_hypertension_with_descendants" ("concept_id", "concept_name") AS (
  SELECT
    "concept_id",
    "concept_name"
  FROM "essential_hypertension"
  UNION ALL
  SELECT
    "c"."concept_id",
    "c"."concept_name"
  FROM "essential_hypertension_with_descendants" AS "eh"
  JOIN "concept_relationship" AS "cr" ON ("eh"."concept_id" = "cr"."concept_id_1")
  JOIN "concept" AS "c" ON ("cr"."concept_id_2" = "c"."concept_id")
  WHERE ("cr"."relationship_id" = 'Subsumes')
)
SELECT *
FROM "essential_hypertension_with_descendants"
=#

The MATERIALIZED annotation can be added using NOTE.

cte =
    FROM(:condition_occurrence) |>
    WHERE(FUN("=", :condition_concept_id, 320128)) |>
    SELECT(:person_id) |>
    NOTE("MATERIALIZED") |>
    AS(:essential_hypertension_occurrence)
#-> (…) |> AS(:essential_hypertension_occurrence)

display(cte)
#=>
ID(:condition_occurrence) |>
FROM() |>
WHERE(FUN("=", ID(:condition_concept_id), LIT(320128))) |>
SELECT(ID(:person_id)) |>
NOTE("MATERIALIZED") |>
AS(:essential_hypertension_occurrence)
=#

print(render(FROM(:essential_hypertension_occurrence) |> SELECT(*) |> WITH(cte)))
#=>
WITH "essential_hypertension_occurrence" AS MATERIALIZED (
  SELECT "person_id"
  FROM "condition_occurrence"
  WHERE ("condition_concept_id" = 320128)
)
SELECT *
FROM "essential_hypertension_occurrence"
=#

A WITH clause without any common table expressions will be omitted.

c = FROM(:condition_occurrence) |>
    SELECT(*) |>
    WITH(args = [])
#-> (…) |> WITH(args = [])

print(render(c))
#=>
SELECT *
FROM "condition_occurrence"
=#