Method parseJoinType

pkg/sql/parser/select_clauses.go:175–255

parseJoinType parses the optional NATURAL keyword and the join-type keywords (LEFT, RIGHT, FULL, INNER, CROSS, OUTER APPLY, …) that precede the JOIN keyword. Returns (joinType string, isNatural bool, err).

()

// (LEFT, RIGHT, FULL, INNER, CROSS, OUTER APPLY, …) that precede the JOIN keyword.
// Returns (joinType string, isNatural bool, err).
func (p *Parser) parseJoinType() (string, bool, error) {
	joinType := "INNER"
	isNatural := false
	explicitType := false // tracks whether a join-type keyword was explicitly given

	// ClickHouse GLOBAL JOIN — consume the GLOBAL modifier before the join type.
	// GLOBAL semantics (distributed join) are not preserved in the AST.
	if p.dialect == string(keywords.DialectClickHouse) && p.isTokenMatch("GLOBAL") {
		p.advance() // consume GLOBAL; fall through to standard join parsing
	}

	// ClickHouse ANY/ALL join strictness prefix — e.g. ANY LEFT JOIN, ALL INNER JOIN.
	// The strictness modifier is consumed but not modeled on the AST.
	if p.dialect == string(keywords.DialectClickHouse) &&
		(p.isType(models.TokenTypeAny) || p.isType(models.TokenTypeAll)) {
		p.advance()
	}

	if p.isType(models.TokenTypeNatural) {
		isNatural = true
		p.advance()
	}

	switch {
	case p.isType(models.TokenTypeLeft):
		joinType = "LEFT"
		explicitType = true
		p.advance()
		if p.isType(models.TokenTypeOuter) {
			p.advance()
		}
	case p.isType(models.TokenTypeRight):
		joinType = "RIGHT"
		explicitType = true
		p.advance()
		if p.isType(models.TokenTypeOuter) {
			p.advance()
		}
	case p.isType(models.TokenTypeFull):
		joinType = "FULL"
		explicitType = true
		p.advance()
		if p.isType(models.TokenTypeOuter) {
			p.advance()
		}
	case p.isType(models.TokenTypeInner):
		joinType = "INNER"
		explicitType = true
		p.advance()
	case p.isType(models.TokenTypeCross):
		joinType = "CROSS"
		explicitType = true
		p.advance()
		if p.dialect == string(keywords.DialectSQLServer) &&
			p.currentToken.Token.Type == models.TokenTypeIdentifier &&
			strings.ToUpper(p.currentToken.Token.Value) == "APPLY" {
			joinType = "CROSS APPLY"
			p.advance()