The standard, section 6.10, <window function>.
syntax rules says:

5) OF shall not contain an outer reference or a <query expression>.

select rank() over (partition by a order by (select max(a) from t2 ) from ten;

• PostgreSQL, Oracle, MS SQL: allow this.

7) If <ntile function>, <lead or lag function>, RANK or DENSE_RANK is specified, then the window ordering clause WOC of WDX shall be present.

select rank() over (partition by a) from ten;

• MariaDB: query works
• PostgreSQL: query works
• Oracle: ORA-30485: missing ORDER BY expression in the window specification
• MS SQL: The function 'rank' must have an OVER clause with ORDER BY.

7) b) The window framing clause of WDX shall not be present.

select rank() over (order by a rows between 1 preceding and 1 following) from ten;

MariaDB: ok (framing ignored)
PG: Ok (framing ignored)
Oracle: ORA-00907: missing right parenthesis
MS SQL: The function 'rank' may not have a window frame.

ORA-30486: invalid window aggregation group in the window specification

11 a) iii) WDEFOC shall contain a single <sort key> SK.

  create table t1 (a int, b int, c int);

  insert into t1 values (1,1,1);

  insert into t1 values (2,2,2);

  select count(*) over (order by a,b range between unbounded preceding and

  current row) from t1;

PG, MS-SQL: ok
Oracle: ORA-30486: invalid window aggregation group in the window specification
MariaDB: crash.

The declared type of SK shall be numeric, datetime, or interval

  create table t1 (a varchar(32), b int, c int);

  insert into t1 values ('aaa',1,1);

  insert into t1 values ('bbbb',2,2);

  select count(*) over (order by a range between unbounded preceding and

  current row) from t1;

PG, MS-SQL: OK
Oracle: OK
Oracle, with "1 PRECEDING": "ORA-00902: invalid datatype"
MariaDB: crash.

If RANGE is specified, then ... i) 2) A) I) If V1P is negative or the null value, then an
exception condition is raised: data exception — invalid preceding or following size in window function.

select count(*) over (rows between -1 preceding and current row ) from t1;

MariaDB: handled by the parser. One gets "Integer is required for ROWS-type frame" error.
PG: ERROR: frame starting offset must not be negative
MS-SQL: Incorrect syntax near 'rows'.
Oracle: No error

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