Focus SQL Review

Focus SQL Review

Review SQL query builder code in the Focus library for correctness, type safety, and API consistency.

When to Use

• Reviewing expression or column implementations
• Analyzing statement builders (SELECT, INSERT, UPDATE, DELETE)
• Checking clause composition
• Validating visitor pattern implementations
• Examining SQL generation logic

Review Checklist

1. Type Safety

• Generic types used correctly (e.g., IntColumn(Int32) vs IntColumn(Int64))
• Expression hierarchy respected (IntExpression, StringExpression, BoolExpression, TimeExpression)
• Column module included properly in column types
• Return types match expected expression types

2. Visitor Pattern

• accept(visitor : SqlVisitor) implemented correctly
• Corresponding visit_* method exists in SqlFormatter
• Inner expressions delegated properly via .try(&.accept(self))

3. SQL Correctness

• Generated SQL is syntactically valid
• Parameters bound safely (no SQL injection)
• Whitespace handling consistent (trailing space convention)
• Identifier quoting applied when needed

4. API Consistency

• Method naming follows Focus conventions (eq, greater_than, etc.)
• Return type is BoolExpression for comparison operations
• Fluent chaining preserved
• Null handling uses is_null / is_not_null pattern

5. Clause Composition

• Clauses implement ordered_clauses correctly for statements
• WHERE, HAVING use expression-based conditions
• SET clause handles both values and subqueries

Key Patterns Reference

See patterns.md for detailed type hierarchy and implementation patterns.

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