urQL/docs/ref-ch07-transform.md

Transform

<transform> ::=
  [ WITH [ <common-table-expression> [ ,...n ] ]
         [ <cte-lib> [ AS ] <alias>  [ ,...n ] ]
  ]
  <cmd>
  [ INTO <table>
    | <set-op> [ ( ] <cmd> [ ) ]
  ] [ ...n ]
  [ AS OF { NOW
          | <timestamp>
          | n { SECONDS | MINUTES | HOURS | DAYS | WEEKS | MONTHS | YEARS } AGO
          | <inline-scalar>
          }
  ]

<cte-lib> pre-built library of <common-table-expression>, TBD.

INTO <table> inserts resulting <table-set> into <table>. Prior <cmd> is terminal.

AS OF defaults to NOW. AS OF <inline-scalar> inline Scalar function that returns <timestamp>.

<set-op> ::=
  UNION
  | EXCEPT
  | INTERSECT
  | DIVIDED BY [ WITH REMAINDER ]
  | PASS-THRU
  | NOP
  | TEE
  | MULTEE

Set operators UNION, etc. apply the previous result collection to the next query result or result from nested queries ( ... ). Left paren ( can only exist singly, but right paren ) may be stacked to any depth ...))).

<cmd> ::=
  <delete>
  | <insert>
  | <merge>
  | <query>
  | <update>

<set-functions> ::=
  <cmd> | <set-op>

API:

+$  transform
  $:
  %transform
  ctes=(list <common-table-expression>)
  (tree <set-functions>)
  ==

Arguments

``

Remarks

<transform> within a CTE may not have its own WITH clause.

The <transform> WITH clause, in which CTEs are grouped, makes each CTE available to subsequent CTEs defined in the parent <transform>.

When used as a <common-table-expression> (CTE) <transform> output must be a pass-thru virtual-table.

Produced Metadata

Exceptions

<table> does not exist GRANT permission on <table> violated AS OF prior to <table> component creation