Method parseJoinedTableRef

pkg/sql/parser/select_subquery.go:261–372

parseJoinedTableRef parses the table reference on the right-hand side of a JOIN.

(joinType string)

// parseJoinedTableRef parses the table reference on the right-hand side of a JOIN.
func (p *Parser) parseJoinedTableRef(joinType string) (ast.TableReference, error) {
	var ref ast.TableReference

	// Optional LATERAL (PostgreSQL)
	isLateral := false
	if p.isType(models.TokenTypeLateral) {
		isLateral = true
		p.advance()
	}

	if p.isType(models.TokenTypeLParen) {
		// Derived table (subquery)
		p.advance() // Consume (

		if !p.isType(models.TokenTypeSelect) && !p.isType(models.TokenTypeWith) {
			return ref, p.expectedError("SELECT in derived table")
		}
		p.advance() // Consume SELECT

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

		if !p.isType(models.TokenTypeRParen) {
			return ref, p.expectedError(")")
		}
		p.advance() // Consume )

		ref = ast.TableReference{Subquery: selectStmt, Lateral: isLateral}
	} else {
		joinedName, err := p.parseQualifiedName()
		if err != nil {
			return ref, goerrors.ExpectedTokenError(
				"table name after "+joinType+" JOIN",
				p.currentToken.Token.Type.String(),
				p.currentLocation(),
				"",
			)
		}
		ref = ast.TableReference{Name: joinedName, Lateral: isLateral}
	}

	// Optional alias.
	// Guard: in MariaDB, CONNECT followed by BY is a hierarchical query clause, not an alias.
	// Similarly, START followed by WITH is a hierarchical query seed, not an alias.
	// Don't consume PIVOT/UNPIVOT as a table alias — they are contextual
	// keywords in SQL Server/Oracle and must reach the pivot-clause parser below.
	if (p.isIdentifier() || p.isType(models.TokenTypeAs)) && !p.isMariaDBClauseStart() && !p.isPivotKeyword() && !p.isUnpivotKeyword() && !p.isQualifyKeyword() && !p.isMinusSetOp() && !p.isSnowflakeTimeTravelStart() && !p.isSampleKeyword() && !p.isMatchRecognizeKeyword() {
		if p.isType(models.TokenTypeAs) {
			p.advance()
			if !p.isIdentifier() {
				return ref, p.expectedError("alias after AS")
			}