expression, types: fix Mod(%), Multiple(*), Minus(-) operators meets inconsistent 0 results.

[wjhuang2016]

What problem does this PR solve?

Fix #11211

What is changed and how it works?

Add a method zeroMyDecimalWithFrac() to get the zero of MyDecimal with the specified result fraction digits

Check List

Tests

• Integration test
• Unit test

Code changes

Side effects

Related changes

[codecov]

Codecov Report

Merging #11251 into master will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff             @@
##             master     #11251   +/-   ##
===========================================
  Coverage   81.4578%   81.4578%           
===========================================
  Files           423        423           
  Lines         90885      90885           
===========================================
  Hits          74033      74033           
  Misses        11544      11544           
  Partials       5308       5308

[SunRunAway]

Hi, after seeing your pull request, it may have other problems with zeroMyDecimal like SELECT 1.111-1.111;

Could you take a review and fix them too?

[SunRunAway]

Please add a comment here to explain these three lines.
And it's better to add a unit test in mydecimal_test.go

[wjhuang2016]

Hi, after seeing your pull request, it may have other problems with zeroMyDecimal like SELECT 1.111-1.111;

Could you take a review and fix them too?

OK

[SunRunAway]

Hi, @wjhuang2016
Is it ok to review?

[wjhuang2016]

Hi, @wjhuang2016
Is it ok to review?

yeah

[SunRunAway]

LGTM 👍

[SunRunAway]

Hi, @wjhuang2016
Although it works as expected, could you add some tests covering cases like(-1.11)+ (1.11)?

[SunRunAway]

/run-all-tests tidb-test=pr/862

[wjhuang2016]

Hi, @wjhuang2016
Although it works as expected, could you add some tests covering cases like(-1.11)+ (1.11)?

It covers -1234.1234 + 1234.1234 and 0.000 / 0.1 now.

[SunRunAway]

LGTM

[qw4990]

LGTM