NULLIF-wrapped integer multiplication reports VARCHAR(3) for the value 9801

A multiplication whose integer operands are wrapped in NULLIF produces the four-character value 9801, but MariaDB infers VARCHAR(3) when the expression is passed to CONCAT. The equivalent multiplication without NULLIF is inferred as VARCHAR(5). This was reproduced on MariaDB 12.3.3.

This occurs when metadata is inferred for a string expression containing multiplication of NULLIF-wrapped integer literals.

Steps to reproduce

1. Save the following as test.sql. The zero-row CREATE TEMPORARY TABLE ... SELECT exposes the inferred metadata without introducing an insertion or SQL-mode error.

CREATE DATABASE width_test;

USE width_test;

CREATE TEMPORARY TABLE widths AS

SELECT CONCAT(NULLIF(99,0) * NULLIF(99,0)) AS wrapped,

       CONCAT(99 * 99) AS direct

WHERE FALSE;

SHOW COLUMNS FROM widths;

SELECT 'values' AS case_name,

 CONCAT(NULLIF(99,0) * NULLIF(99,0)), CONCAT(99 * 99);

DROP TEMPORARY TABLE widths;

DROP DATABASE width_test;

1. Run the script with the MariaDB client:

mariadb < test.sql

Actual result

The recorded execution returned:

Field    Type        Null  Key  Default  Extra

wrapped  varchar(3)  YES        NULL

 direct  varchar(5)  YES        NULL

values   9801        9801

The NULLIF-wrapped expression therefore generates four characters but is assigned a declared width of three.

Expected result

The inferred type of each expression should be wide enough to hold the value generated by that expression. Exact equality between the two inferred widths is not required, and the direct expression may remain conservatively sized, but wrapped must be at least VARCHAR(4) for 9801.

Source context

The supplied source suggests that NULLIF copies result attributes from its operand without the generic normalization used by some other expression wrappers. Generic integer precision is then derived from that display width, and multiplication uses the operand precisions to determine its result width. This is consistent with the observed VARCHAR(3) metadata, but is presented as a source-supported explanation rather than a proven complete root cause.