No warning is produced on microsecond precision truncation, as it is done for other data types

When a value with microseconds is truncated while being inserted into a time column, it does not cause a warning, as it happens in the similar situation with other data types:

Microseconds truncated, no warning:

CREATE TABLE t (c1 TIME(3));

INSERT INTO t VALUES ('10:11:12.12345');

SELECT * FROM t;

c1

10:11:12.123

Fractional part of a decimal value truncated, a warning is produced:

CREATE TABLE t (d DECIMAL(5,3));

INSERT INTO t VALUES (12.34567);

Warnings:

Note	1265	Data truncated for column 'd' at row 1

SELECT * FROM t;

d

12.346

It might cause a confusion, especially if a user does not expect that the server knows about microseconds and takes them into account:

CREATE TABLE t (c1 TIME);

INSERT INTO t VALUES ('10:11:12.123');

SELECT * FROM t WHERE c1 = '10:11:12.123';

c1

DROP TABLE t;

The empty result set is understandable considering that TIME is actually TIME(0), and that the inserted value is silently truncated, while in the select the string literal is converted into a temporal value with microseconds; but it is not obvious at all without a warning about truncation.