added changes for better build ordering when SQL expressions are pres…

[ronanstokes-db]

Proposed changes

Improvement to reduce number of times explicit baseColumn is needed to be specified when a column definition has references to previous columns inside of the SQL expression clause.

It uses a simple identifier parser to determine when there are potential references to earlier columns and adjusts the separation of phases for column building

Types of changes

What types of changes does your code introduce to dbldatagen? Put an x in the boxes that apply

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Change to tutorials, tests or examples
• [ ] Non code change (readme, images or other non-code assets)
• [x] Documentation Update (if none of the other choices apply)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• [ ] Lint and unit tests pass locally with my changes
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] I have added necessary documentation (if appropriate)
• [] Any dependent changes have been merged and published in downstream modules
• [x] Submission does not reduce code coverage numbers
• [ ] Submission does not increase alerts or messages from LGTM

Further comments

Each phase of column generation produces a select statement to generate the columns. When the SQL expression refers to other columns, they must have been generated in a previous select statement.

This adjusts the assignment of column generators to select statements.

[codecov[bot]]

Codecov Report

Merging #159 (f23557b) into master (fefd904) will increase coverage by 0.17%. The diff coverage is 96.20%.

@@            Coverage Diff             @@
##           master     #159      +/-   ##
==========================================
+ Coverage   90.15%   90.33%   +0.17%     
==========================================
  Files          22       22              
  Lines        2439     2515      +76     
  Branches      396      416      +20     
==========================================
+ Hits         2199     2272      +73     
- Misses        157      158       +1     
- Partials       83       85       +2     

Impacted Files	Coverage Δ
dbldatagen/__init__.py	90.90% <ø> (ø)
dbldatagen/utils.py	90.37% <90.00%> (-0.07%)	:arrow_down:
dbldatagen/data_generator.py	84.72% <96.87%> (+0.68%)	:arrow_up:
dbldatagen/schema_parser.py	97.67% <100.00%> (+0.41%)	:arrow_up:

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.