Allow optional keywords in create table unique constraints

[kayman-mk]

Brief summary of the change made

Allows optional keywords and index name in unique constraints of create table.

CREATE TABLE a(
    a INT NOT NULL,
    UNIQUE KEY (a),
    UNIQUE INDEX (a),
    UNIQUE KEY idx_a(a),
    UNIQUE idx_b(a),
    UNIQUE (a),
);

• the index name is optional
• key and index keywords are optional

At least MySql and PostgreSql are using this syntax. I didn't found anything in SQL-99 but the implementation was already present in dialect_mysql.py

Are there any other side effects of this change that we should be aware of?

No.

Pull Request checklist

• Please confirm you have completed any of the necessary steps below.

• Included test cases to demonstrate any code changes, which may be one or more of the following:

  • .yml rule test cases in test/fixtures/rules/std_rule_cases.
  • .sql/.yml parser test cases in test/fixtures/dialects (note YML files can be auto generated with python test/generate_parse_fixture_yml.py or by running tox locally).
  • Full autofix test cases in test/fixtures/linter/autofix.
  • Other.

• Added appropriate documentation for the change.

• Created GitHub issues for any relevant followup/future enhancements if appropriate.

[jpy-git]

@kayman-mk I'm conscious that this PR is impacting the same area of the code as #2076 that we've just merged in. Can you update your fork and deal with any potential merge conflicts before I review?

[kayman-mk]

@jpy-git Branch updated. No conflicts found.

[codecov]

Codecov Report

Merging #2077 (923fed5) into main (982aef1) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main     #2077   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          148       148           
  Lines        10599     10603    +4     
=========================================
+ Hits         10599     10603    +4     

Impacted Files	Coverage Δ
src/sqlfluff/dialects/dialect_mysql.py	100.00% <100.00%> (ø)

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[jpy-git]

So I can see this implementation in the mysql docs: https://dev.mysql.com/doc/refman/8.0/en/create-table.html#:~:text=%5BCONSTRAINT%20%5Bsymbol%5D%5D%20UNIQUE%20%5BINDEX%20%7C%20KEY%5D

However reading the postgres docs the syntax for unique constraints seems to be different?: https://www.postgresql.org/docs/14/sql-createtable.html

[jpy-git]

@kayman-mk can you move this logic to mysql specific please?

[jpy-git]

@kayman-mk great work, thanks for adding this! 🥇

For some reason I don't have the usual option to update the branch for the latest changes in main 🤷

Could you just pull in the latest changes from main and then we can get this merged in? Thanks 😄

[tunetheweb]

For some reason I don't have the usual option to update the branch for the latest changes in main 🤷

When people open a PR there’s a tick box to allow maintainers to alter the branch. Most people leave it ticked to allow small changes and updates to be applied.

[jpy-git]

@tunetheweb ah makes sense thanks! 😄