* Base Report data store utility functions - 1
Standardizing the data store classes will be easier if the base class contains simple utility functions
that can replace logic implemented in multiple data stores.
- set_db_table_name() assigns a WP DB table name class variable for the data store
- get_db_table_name() retrieves the WP DB table name
- prepend_table_name() prepends a field in a query fragment with the data store table name
* add context, clause handling, and filters to reports data store
* add generated SQL clauses to class properties
* reduce id getter logic to single function with filter, add phpdocs to new filters
* update table_name to private string for use in constructor
* extract SQL query clause handling to its own class
- Will allow for use in subquery processing without creating a get_data stub
- Swap parameter order in add_sql_clause for readability
- Add support for clearing multple clauses in one call
* add context var to SqlQuery class
* implement SqlQuery in Categories data store
* implement subquery in categories data store
* coupons data stores, more underlying refactor
- fix warnings
- make filtered id functions static
- add limit parameter handling
- update coupons data store
- update coupon stats data store
* refactor coupon stats data store
* refactor customers and customer stats data stores
* add context to subqueries
* add missed prepend table name call
* refactor downloads data store, fix some warnings
* fix warnings, add separator parameter to filtered IDs
* refactor taxes and tax stats data stores
* refactor variations data store
* refactor product and product stats data stores
* make table_name static throughout for compat with static hook functions
* refactor order and order stats datastores
- use consistent visibility on initialize_queries()
- update db_table_name logic to use static keyword instead of self
* fix missed whitespace
* fix segmenting query, add SqlQuery join clause
* DRY data store constructors, class properties
* prefix table name when not yet assigned
* fix unit tests, interpolations, WPDB delete calls
* DRY get_object_where_filter()
* remove redundant table prefix from unit test init
* fix refactored SQL queries
* restore product paging
* remove unused query param arrays
* add first pass on data docs readme
* remove debug code, errant SQL spacing
* refactor out outer_from query element
* merge wheres, joins before filtering
* move all report column definitions to assign_report_columns
* fix data readme markdown
* small code formating fixes from review
* remove static from query/datastore context
* missed self:: in previous, add comments, small code moves
* rename get_statement() to get_query_statement()
* remove temporary query references
* static reference, remove reference parameter, fix coupon compare
* add todo reminders
* use correct query parameter in coupon data stores
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