types: fix Restore of FieldType in handling decimal

[lonng]

Signed-off-by: Lonng chris@lonng.org

What problem does this PR solve?

Consider the following create table statement:

create table t(a decimal(20) not null);

If we parse it and restore it will get an unexpected result: create table t(a decimal not null).

The result should keep consistent with show create table t which emit create table t(a decimal(20, 0) not null)

What is changed and how it works?

Fix it

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

N/A

Side effects

N/A

Related changes

• Need to cherry-pick to the release branch

[IANTHEREAL]

LGTM

[IANTHEREAL]

@tiancaiamao PTAL

[bb7133]

Please add some test cases, thanks!

[kennytm]

(Fixed in #311 too)

[lonng]

Closed due to fixed in #311