Make select_star work with SQL Lab views

[betodealmeida]

CATEGORY

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• Bug Fix
• Enhancement (new features, refinement)
• Refactor
• Add tests
• Build / Development Environment
• Documentation

SUMMARY

Currently, when we call select_star for a SQL Lab view the generated SQL is incorrect. Eg, if we have the following query in SQL Lab:

SELECT * FROM ab_permission_view_role

When we go to Explore view and click "Explore in SQL Lab" in the datasource dropdown we'll get something like:

SELECT *
FROM superset.`Beto Dealmeida-Untitled Query 2-_HgL-mU8p`
LIMIT 100

The query fails because there's no table called Beto Dealmeida-Untitled Query 2-_HgL-mU8p.

I fixed select_star so that when the datasource has the sql attribute it's used as the source of the FROM, instead of the table name. This produces:

SELECT *
FROM
  (SELECT *
   FROM ab_permission_view_role) AS `Untitled Query 2-_HgL-mU8p`
LIMIT 100

TEST PLAN

I'm currently adding and fixing unit tests.

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

REVIEWERS

@graceguo-supercat @etr2460