Date Dimension And Calendar Table Generator

## CONTEXT
You are helping me build a date dimension table for time-based reporting in a data warehouse. I need calendar, ISO-week, and fiscal attributes so dashboards can group and compare by any time grain. Assume a modern SQL warehouse in 2026 and that this table joins to fact tables via a date key.

## ROLE
Act as a data warehouse engineer who has built date dimensions for many reporting systems. You know the subtleties of ISO weeks, fiscal calendars, leap years, and holiday flags, and you produce a table that handles period-over-period comparisons cleanly.

## RESPONSE GUIDELINES
- Confirm the calendar boundaries and fiscal rules first.
- Provide generation SQL that produces one row per day.
- Document every column and its intended use.
- Flag dialect-specific date functions used.

## TASK CRITERIA

### Generate The Spine
- Create one row per day across the requested date range.
- Use a sequence or recursive method portable to my dialect.
- Define a stable integer date key like YYYYMMDD.
- Include the actual date column for joins and display.

### Add Calendar Attributes
- Include year, quarter, month, day, and day-of-week.
- Add month and day names plus abbreviations.
- Flag weekends and provide week-start and week-end dates.
- Include day-of-year and week-of-year values.

### Add ISO And Fiscal Attributes
- Compute ISO year, ISO week, and ISO day correctly.
- Add fiscal year, quarter, and period per my fiscal start.
- Provide period start and end dates for each grain.
- Handle 53-week years and fiscal edge cases.

### Add Comparison Helpers
- Add prior-period and same-period-last-year keys.
- Flag the first and last day of each period.
- Provide relative offsets like days-from-today.
- Mark holidays and business days if I supply a list.

### Make It Maintainable
- Document refresh strategy and extending the range.
- Recommend indexing or clustering on the date key.
- Note timezone assumptions for the calendar.
- Provide a validation query for gaps or duplicates.

## ASK THE USER FOR
- The start and end dates for the calendar.
- Your fiscal year start month and week rules.
- Your SQL dialect.
- Any holiday list or business-day rules to include.