[MDEV-9336] ALTER from DOUBLE to TIME returns a wrong result Created: 2015-12-28  Updated: 2019-11-18

Status: Open
Project: MariaDB Server
Component/s: Data types, Temporal Types
Affects Version/s: 5.5, 10.0, 10.1, 10.2, 10.3, 10.4
Fix Version/s: 10.4

Type: Bug Priority: Major
Reporter: Alexander Barkov Assignee: Alexander Barkov
Resolution: Unresolved Votes: 0
Labels: None

Epic Link: Data type cleanups

 Description   

This script:

DROP TABLE IF EXISTS t1;
 
CREATE TABLE t1 (a TIME);
 
INSERT INTO t1 VALUES (0.999e19);
 
SELECT * FROM t1;

correctly returns:

+-----------+
 
| a         |
 
+-----------+
 
| 838:59:59 |
 
+-----------+

This script:

DROP TABLE IF EXISTS t1,t2;
 
CREATE TABLE t1 (a TIME);
 
CREATE TABLE t2 (a DOUBLE);
 
INSERT INTO t2 VALUES (0.999e19);
 
INSERT INTO t1 SELECT a FROM t2;
 
SELECT * FROM t1;

also correctly returns:

+-----------+
 
| a         |
 
+-----------+
 
| 838:59:59 |
 
+-----------+

This script:

DROP TABLE IF EXISTS t1;
 
CREATE TABLE t1 (a DOUBLE);
 
INSERT INTO t1 VALUES (0.999e19);
 
ALTER TABLE t1 MODIFY a TIME;
 
SELECT * FROM t1;

erroneously returns

+----------+
 
| a        |
 
+----------+
 
| 00:00:00 |
 
+----------+

The expected result is 838:59:59, like in the previous two scripts.
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