Method parseMergeWhenClause

pkg/sql/parser/dml_merge.go:129–184

parseMergeWhenClause parses a WHEN clause in a MERGE statement

()

// parseMergeWhenClause parses a WHEN clause in a MERGE statement
func (p *Parser) parseMergeWhenClause() (*ast.MergeWhenClause, error) {
	clause := &ast.MergeWhenClause{}

	p.advance() // Consume WHEN

	// Determine clause type: MATCHED, NOT MATCHED, NOT MATCHED BY SOURCE
	if p.isType(models.TokenTypeMatched) || p.currentToken.Token.Value == "MATCHED" {
		clause.Type = "MATCHED"
		p.advance() // Consume MATCHED
	} else if p.isType(models.TokenTypeNot) {
		p.advance() // Consume NOT
		if !p.isType(models.TokenTypeMatched) && p.currentToken.Token.Value != "MATCHED" {
			return nil, p.expectedError("MATCHED after NOT")
		}
		p.advance() // Consume MATCHED

		// Check for BY SOURCE
		if p.isType(models.TokenTypeBy) {
			p.advance() // Consume BY
			if !p.isType(models.TokenTypeSource) && p.currentToken.Token.Value != "SOURCE" {
				return nil, p.expectedError("SOURCE after BY")
			}
			p.advance() // Consume SOURCE
			clause.Type = "NOT_MATCHED_BY_SOURCE"
		} else {
			clause.Type = "NOT_MATCHED"
		}
	} else {
		return nil, p.expectedError("MATCHED or NOT MATCHED")
	}

	// Parse optional AND condition
	if p.isType(models.TokenTypeAnd) {
		p.advance() // Consume AND
		condition, err := p.parseExpression()
		if err != nil {
			return nil, goerrors.WrapError(goerrors.ErrCodeInvalidSyntax, "error parsing WHEN condition", models.Location{}, "", err)
		}
		clause.Condition = condition
	}

	// Parse THEN
	if !p.isType(models.TokenTypeThen) {
		return nil, p.expectedError("THEN")
	}
	p.advance() // Consume THEN

	// Parse action (UPDATE, INSERT, DELETE)
	action, err := p.parseMergeAction(clause.Type)
	if err != nil {
		return nil, err
	}
	clause.Action = action

	return clause, nil
}

// parseMergeAction parses the action in a WHEN clause