Bug #121215 CAST(number AS TIME): overflow handling splits by digit count; 11–12 digits silently return 00:00:00

• Submitted: 3 Sep 7:26
• Modified: 3 Sep 9:25
• Reporter: Chunling Qin
• Status: Not a Bug
• Category: MySQL Server: DML
• Severity: S3 (Non-critical)
• Version: 9.7.2
• OS: Any
• CPU Architecture: Any

[3 Sep 7:26] Chunling Qin

Description:

mysql> SELECT CAST(999999999  AS TIME);   -- NULL + Warning 1292 (correct failure)
+--------------------------+
| CAST(999999999  AS TIME) |
+--------------------------+
| NULL                     |
+--------------------------+
1 row in set, 1 warning (0.00 sec)

mysql> SELECT CAST(9999999999 AS TIME);   -- NULL + Warning 1292
+--------------------------+
| CAST(9999999999 AS TIME) |
+--------------------------+
| NULL                     |
+--------------------------+
1 row in set, 1 warning (0.00 sec)

mysql> SELECT CAST(10000000000 AS TIME);  -- 00:00:00  ← silently zeroed, NO warning
+---------------------------+
| CAST(10000000000 AS TIME) |
+---------------------------+
| 00:00:00                  |
+---------------------------+
1 row in set (0.00 sec)

mysql> SELECT CAST(100000000000 AS TIME); -- 00:00:00  ← silently zeroed, NO warning
+----------------------------+
| CAST(100000000000 AS TIME) |
+----------------------------+
| 00:00:00                   |
+----------------------------+
1 row in set (0.00 sec)

mysql> SELECT CAST(99999999999999 AS TIME);      -- NULL + Warning 1292
+------------------------------+
| CAST(99999999999999 AS TIME) |
+------------------------------+
| NULL                         |
+------------------------------+
1 row in set, 1 warning (0.00 sec)

mysql> SELECT CAST(-10000000000 AS TIME);        -- NULL + Warning 1292 (negatives unaffected)
+----------------------------+
| CAST(-10000000000 AS TIME) |
+----------------------------+
| NULL                       |
+----------------------------+
1 row in set, 1 warning (0.00 sec)

Silent window: exactly positive integers in [10^10, 10^12]; outside the window, consistently NULL + warning.

DML split (same number, different behavior per path):

CREATE TABLE ti (c TIME);
INSERT INTO ti VALUES (9999999999);   -- ERROR 1292 Incorrect time value (rejected — correct)
INSERT INTO ti VALUES (10000000000);  -- silently stores 00:00:00, NO warning

the number→TIME intermediate representation takes a different branch inside the 11–12 digit window (suspected: double/decimal stringified intermediate partially parsed by str_to_time), producing an "effective 0" instead of a failure.

How to repeat:
SELECT CAST(999999999  AS TIME);   -- NULL + Warning 1292 (correct failure)
SELECT CAST(9999999999 AS TIME);   -- NULL + Warning 1292
SELECT CAST(10000000000 AS TIME);  -- 00:00:00  ← silently zeroed, NO warning
SELECT CAST(100000000000 AS TIME); -- 00:00:00  ← silently zeroed, NO warning
SELECT CAST(99999999999999 AS TIME);      -- NULL + Warning 1292
SELECT CAST(-10000000000 AS TIME);        -- NULL + Warning 1292 (negatives unaffected)

[3 Sep 7:27] Chunling Qin

Add version.

[3 Sep 9:25] Roy Lyseng

Thank you for the bug report.
However, this is not a bug.
10000000000 is a (half)valid datetime constant, representing 0001-00-00 00:00:00, which it is possible to cast into a TIME value.