Method parseFromTableReference

pkg/sql/parser/select_subquery.go:32–258

parseFromTableReference parses a single table reference in a FROM clause, including derived tables (subqueries), LATERAL, and optional aliases.

()

// parseFromTableReference parses a single table reference in a FROM clause,
// including derived tables (subqueries), LATERAL, and optional aliases.
func (p *Parser) parseFromTableReference() (ast.TableReference, error) {
	var tableRef ast.TableReference

	// Check for LATERAL keyword (PostgreSQL)
	isLateral := false
	if p.isType(models.TokenTypeLateral) {
		isLateral = true
		p.advance() // Consume LATERAL
	}

	// Check for derived table (subquery in parentheses)
	if p.isType(models.TokenTypeLParen) {
		p.advance() // Consume (

		// Check if this is a subquery (starts with SELECT or WITH)
		if !p.isType(models.TokenTypeSelect) && !p.isType(models.TokenTypeWith) {
			return tableRef, p.expectedError("SELECT in derived table")
		}

		// Consume SELECT token before calling parseSelectStatement
		p.advance() // Consume SELECT

		// Parse the subquery
		subquery, err := p.parseSelectStatement()
		if err != nil {
			return tableRef, err
		}
		selectStmt, ok := subquery.(*ast.SelectStatement)
		if !ok {
			return tableRef, p.expectedError("SELECT statement in derived table")
		}

		// Expect closing parenthesis
		if !p.isType(models.TokenTypeRParen) {
			return tableRef, p.expectedError(")")
		}
		p.advance() // Consume )

		tableRef = ast.TableReference{
			Subquery: selectStmt,
			Lateral:  isLateral,
		}
	} else if p.dialect == string(keywords.DialectSnowflake) &&
		p.isType(models.TokenTypePlaceholder) && strings.HasPrefix(p.currentToken.Token.Value, "@") {
		// Snowflake stage reference: @stage_name or @db.schema.stage/path.
		// Tokenized as PLACEHOLDER; consume as a table name.
		// Gated to Snowflake to avoid misinterpreting @variable in other dialects.
		stageName := p.currentToken.Token.Value
		p.advance()
		// Optional /path suffix — consume tokens joined by / until a space boundary.
		// Slash tokenizes as TokenTypeDiv.
		for p.isType(models.TokenTypeDiv) {
			stageName += "/"
			p.advance()
			if p.isIdentifier() || p.isType(models.TokenTypeKeyword) {
				stageName += p.currentToken.Token.Value
				p.advance()
			}