expression: handle ErrTruncated when dividing decimals in non-data-change stmts

[qw4990]

What problem does this PR solve?

Handle ErrTruncated when dividing decimals.
Before this PR:

mysql> select cast(1 as decimal(60,30)) / cast(3 as decimal(60,30)) / cast(3 as decimal(60, 30));
ERROR 1265 (01000): Data truncated for column '%s' at row %d

After this PR:

mysql> select cast(1 as decimal(60,30)) / cast(3 as decimal(60,30)) / cast(3 as decimal(60, 30));
+------------------------------------------------------------------------------------+
| cast(1 as decimal(60,30)) / cast(3 as decimal(60,30)) / cast(3 as decimal(60, 30)) |
+------------------------------------------------------------------------------------+
|                                                   0.111111111111111111111111111111 |
+------------------------------------------------------------------------------------+

In MySQL:

mysql> select cast(1 as decimal(60,30)) / cast(3 as decimal(60,30)) / cast(3 as decimal(60, 30));
+------------------------------------------------------------------------------------+
| cast(1 as decimal(60,30)) / cast(3 as decimal(60,30)) / cast(3 as decimal(60, 30)) |
+------------------------------------------------------------------------------------+
|                                                   0.111111111111111111111111111111 |
+------------------------------------------------------------------------------------+

Check List

Tests

• Unit test

[qw4990]

/run-all-tests

[SunRunAway]

Please fix the test case.