[DERBY-896] Cast date to timestamp results in "ERROR 42846: Cannot convert types 'DATE' to 'TIMESTAMP'."

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 10.1.2.1
• Fix Version/s: 10.10.2.0, 10.11.1.1
• Component/s: SQL
• Labels: derby_triage10_5_2
• Environment: --------- Derby Information --------; JRE - JDBC: J2SE 1.4.2 - JDBC 3.0; [D:\Programme\Derby\bin\lib\derby.jar] 10.1.2.1 - (330608); [D:\Programme\Derby\bin\lib\derbytools.jar] 10.1.2.1 - (330608)
• Urgency: Normal
• Issue & fix info: Repro attached
• Assignee: Knut Anders Hatlen
• Reporter: Oleksandr Alesinskyy
• Created: 31/Jan/06 21:20
• Updated: 21/Jan/15 00:23
• Resolved: 06/Mar/14 17:24

Description

Cast date to timestamp results in "ERROR 42846: Cannot convert types 'DATE' to 'TIMESTAMP'.",
e.g. in ij:
select cast(cast ('2006-01-01' as date) as timestamp) from sys.sysschemas;
or
select cast (current_date as timestamp) from bradi_dat.lpaip01;

The similar issue exists for time ("ERROR 42846: Cannot convert types 'TIME' to 'TIMESTAMP'.",

Documentation clearly states that these conversions are allowed, see table 1 in a description of CAST function in the Derby Reference Manual and comment about "Conversion of date/time values" below that table (see below as well).

Conversions of date/time values
A date/time value can always be converted to and from a TIMESTAMP. If a DATE is
converted to a TIMESTAMP, the TIME component of the resulting TIMESTAMP is always
00:00:00. If a TIME data value is converted to a TIMESTAMP, the DATE component is
set to the value of CURRENT_DATE at the time the CAST is executed. If a TIMESTAMP
is converted to a DATE, the TIME component is silently truncated. If a TIMESTAMP is
converted to a TIME, the DATE component is silently truncated.

Issue Links

• is related to: DERBY-6481 Derby 10.10 backport issue (winter/spring 2014)
• relates to: DERBY-6501 change 10.10 version of CastingTest.java to build/run under jsr169