Grouped aggregate output changes from `NULL` to a numeric value after view materialization.

[123lpygithub]

Under SQL-equivalent rewriting, the source and mutated queries differ only in extracting the grouped aggregate into a view. The aggregate output changes from NULL to 1.

Version: 8.0.44-alisql-dev

How to repeat:

DROP VIEW IF EXISTS v;
DROP TABLE IF EXISTS t;

CREATE TABLE t (
  c1 TINYINT NOT NULL,
  c6 VARCHAR(1) NOT NULL
);

CREATE UNIQUE INDEX idx_t_c1 ON t (c1);
CREATE INDEX idx_t_c6 ON t (c6);

INSERT INTO t VALUES (1, 'x');

-- Original SQL
SELECT SUM(DISTINCT c1) AS s,
       ROW_NUMBER() OVER () AS r
FROM t
GROUP BY c6;

-- View SQL
CREATE VIEW v AS
SELECT SUM(DISTINCT c1) AS s,
       c6
FROM t
GROUP BY c6;

-- Mutated SQL
SELECT s,
       ROW_NUMBER() OVER () AS r
FROM v;

Observed mismatch:

• original result:

s	r
NULL	1

• mutated result:

s	r
1	1