QAIL PostgreSQL Expressions Guide | AST Coverage and SQL Mapping

Coverage Summary

Area	Coverage	AST Capabilities & Notes
Expressions	Supported	Core query nodes, JSON querying, arrays, subscripts, and custom collations
DML Actions	Supported	Full read/write operations mapping straight to binary wire protocol formats
DDL Actions	Supported	Schema control, index setups, view generators, and database lifecycle management

Expression Node	QAIL AST Builder API	Transpiled SQL Example	Compatibility
`Expr::Named`	`Expr::Named("email".into())`	`email`	Supported
`Expr::Aliased`	`Expr::Aliased(name, alias)`	`users.email AS user_email`	Supported
`Expr::Aggregate`	`Expr::Aggregate(func, col, filter)`	`COUNT(*) FILTER (WHERE ...) AS cnt`	Supported
`Expr::Window`	`Expr::Window(func, partition, order, frame)`	`SUM(amount) OVER (PARTITION BY dept ORDER BY date)`	Supported
`Expr::Case`	`Expr::Case(when_clauses, else_value)`	`CASE WHEN ... THEN 'A' ELSE 'B' END`	Supported
`Expr::ArrayConstructor`	`Expr::ArrayConstructor(elements, alias)`	`ARRAY[col1, col2] AS arr`	New Node
`Expr::RowConstructor`	`Expr::RowConstructor(elements, alias)`	`ROW(id, name) AS person`	New Node
`Expr::Subscript`	`Expr::Subscript(expr, index, alias)`	`tags[1] AS first_tag`	New Node
`Expr::Collate`	`Expr::Collate(expr, collation)`	`name COLLATE "C"`	New Node
`Expr::FieldAccess`	`Expr::FieldAccess(expr, field, alias)`	`(address).city AS city`	New Node
`Expr::Cast`	`Expr::Cast(expr, target_type)`	`id::TEXT`	Supported
`Expr::JsonAccess`	`Expr::JsonAccess(column, path_segments)`	`data->'user'->>'name' AS name`	Supported