Method parseMergeAction

pkg/sql/parser/dml_merge.go:187–312

parseMergeAction parses the action in a WHEN clause

(clauseType string)

// parseMergeAction parses the action in a WHEN clause
func (p *Parser) parseMergeAction(clauseType string) (*ast.MergeAction, error) {
	action := &ast.MergeAction{}

	if p.isType(models.TokenTypeUpdate) {
		action.ActionType = "UPDATE"
		p.advance() // Consume UPDATE

		// Parse SET
		if !p.isType(models.TokenTypeSet) {
			return nil, p.expectedError("SET after UPDATE")
		}
		p.advance() // Consume SET

		// Parse SET clauses
		for {
			if !p.isIdentifier() && !p.canBeAlias() {
				return nil, p.expectedError("column name")
			}
			// Handle qualified column names (e.g., t.name)
			columnName := p.currentToken.Token.Value
			p.advance()

			// Check for qualified name (table.column)
			if p.isType(models.TokenTypePeriod) {
				p.advance() // Consume .
				if !p.isIdentifier() && !p.canBeAlias() {
					return nil, p.expectedError("column name after .")
				}
				columnName = fmt.Sprintf("%s.%s", columnName, p.currentToken.Token.Value)
				p.advance()
			}

			setClause := ast.SetClause{Column: columnName}

			if !p.isType(models.TokenTypeEq) {
				return nil, p.expectedError("=")
			}
			p.advance() // Consume =

			value, err := p.parseExpression()
			if err != nil {
				return nil, goerrors.WrapError(goerrors.ErrCodeInvalidSyntax, "error parsing SET value", models.Location{}, "", err)
			}
			setClause.Value = value
			action.SetClauses = append(action.SetClauses, setClause)

			if !p.isType(models.TokenTypeComma) {
				break
			}
			p.advance() // Consume comma
		}
	} else if p.isType(models.TokenTypeInsert) {
		if clauseType == "MATCHED" || clauseType == "NOT_MATCHED_BY_SOURCE" {
			return nil, goerrors.InvalidSyntaxError(fmt.Sprintf("INSERT not allowed in WHEN %s clause", clauseType), models.Location{}, "")
		}
		action.ActionType = "INSERT"
		p.advance() // Consume INSERT