Bug#119727: Fix wrong result for 'value BETWEEN a AND NULL' with temporal types

[khaledalam]

Description

• Fixes incorrect result when using BETWEEN with mixed temporal types (DATE, TIMESTAMP, YEAR) where one bound is NULL
• The expression '2019-12-25' BETWEEN '2017-05-24' AND NULL was returning 0 instead of NULL

Root Cause

When YEAR is mixed with DATE/TIMESTAMP in BETWEEN, type aggregation returns REAL_RESULT. This bypassed temporal comparison, causing incompatible val_real() formats to be compared:

• DATE → 20191225.0
• TIMESTAMP → 20170524000000.0

Since 20191225.0 < 20170524000000.0, the value appeared less than the lower bound, returning FALSE before checking the NULL upper bound.

Solution

Added all_temporal check in Item_func_between::resolve_type() to force temporal comparison when all three arguments are temporal types, regardless of the aggregated cmp_type.

Plan

• Added new test file func_between_temporal.test with 8 test cases
• Verified fix compiles without errors
• All new tests pass

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