ddl: support constraint in create table.

[AilinKid]

Signed-off-by: Arenatlx 314806019@qq.com

What problem does this PR solve?

Close issue: pingcap#17406
Problem Summary:
Implement check constraints in TiDB
For example:

create table t(a int constraint haha check(a>1), constraint hehe check(a<10));

the column-level haha check constraint and table-level hehe constraint now can be checked and attach-stored in tableInfo.

What is changed and how it works?

What's Changed:
1: modify tableInfo add constraint field.
2: handle the constraint from parser, do dependency check in ddl, and store it.
3: do some test about it

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:

Check List

Tests

• Unit test
• Integration test

Side effects

• Breaking backward compatibility

Release note

• implement the check constraints in create table

[djshow832]

LGTM

[imtbkcat]

LGTM