Method parseColumnConstraint

pkg/sql/parser/ddl_columns.go:134–290

parseColumnConstraint parses a single column constraint Returns (constraint, found, error)

()

// parseColumnConstraint parses a single column constraint
// Returns (constraint, found, error)
func (p *Parser) parseColumnConstraint() (*ast.ColumnConstraint, bool, error) {
	constraint := &ast.ColumnConstraint{}

	// PRIMARY KEY
	if p.isType(models.TokenTypePrimary) {
		p.advance() // Consume PRIMARY
		if !p.isType(models.TokenTypeKey) {
			return nil, false, p.expectedError("KEY after PRIMARY")
		}
		p.advance() // Consume KEY
		constraint.Type = "PRIMARY KEY"
		return constraint, true, nil
	}

	// NOT NULL
	if p.isType(models.TokenTypeNot) {
		p.advance() // Consume NOT
		if !p.isType(models.TokenTypeNull) {
			return nil, false, p.expectedError("NULL after NOT")
		}
		p.advance() // Consume NULL
		constraint.Type = "NOT NULL"
		return constraint, true, nil
	}

	// NULL (explicit nullable)
	if p.isType(models.TokenTypeNull) {
		p.advance() // Consume NULL
		constraint.Type = "NULL"
		return constraint, true, nil
	}

	// UNIQUE
	if p.isType(models.TokenTypeUnique) {
		p.advance() // Consume UNIQUE
		constraint.Type = "UNIQUE"
		return constraint, true, nil
	}

	// DEFAULT value
	if p.isType(models.TokenTypeDefault) {
		p.advance() // Consume DEFAULT
		constraint.Type = "DEFAULT"

		// Parse default value - can be a literal, function call, or expression in parentheses
		expr, err := p.parseExpression()
		if err != nil {
			return nil, false, err
		}
		constraint.Default = expr
		return constraint, true, nil
	}

	// CHECK (expression)
	if p.isType(models.TokenTypeCheck) {
		p.advance() // Consume CHECK
		constraint.Type = "CHECK"