Method parseImpl

src/Parsers/ParserUpdateQuery.cpp:17–119

To get more info of the grammar, see ASTUpdateQuery.h .

/// To get more info of the grammar, see ASTUpdateQuery.h .
bool ParserUpdateQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
{
    auto query = std::make_shared<ASTUpdateQuery>();
    node = query;

    ParserKeyword s_update("UPDATE");
    ParserKeyword s_set("SET");
    ParserKeyword s_where("WHERE");
    ParserKeyword s_order_by("ORDER BY");
    ParserKeyword s_limit("LIMIT");
    ParserKeyword s_settings("SETTINGS");

    ParserList parser_assignment_list(std::make_unique<ParserAssignmentWithAlias>(dt), std::make_unique<ParserToken>(TokenType::Comma), false);
    ParserExpression exp_list(dt);
    ParserOrderByExpressionList order_list(dt);
    ParserExpressionWithOptionalAlias exp_elem(false, dt);

    if (!s_update.ignore(pos, expected))
        return false;

    auto pos_before = pos;
    /// extract the target table
    if (!parseDatabaseAndTableName(pos, expected, query->database, query->table))
        return false;

    if (s_set.ignore(pos, expected))
    {
        /// If the target table is followed by the word 'SET', it means it's a UPDATE SINGLE TABLE query, and all tables are extracted.
        query->single_table = true;
    }
    else
    {
        /// For UPDATE JOIN, we already extract the target table and store the info to query->database and query->table.
        /// To parse the whole `tables` correctly, we need to retrace tokens from the beginning of target table. 
        query->single_table = false;
        pos = pos_before;

        /// extract all tables
        if (!ParserTablesInSelectQuery(dt).parse(pos, query->tables, expected))
            return false;

        if (!s_set.ignore(pos, expected))
            return false;
    }

    if (!parser_assignment_list.parse(pos, query->assignment_list, expected))
        return false;

    if (s_where.ignore(pos, expected))
    {
        if (!exp_list.parse(pos, query->where_condition, expected))
            return false;
    }

    if (s_order_by.ignore(pos, expected))
    {
        if (!order_list.parse(pos, query->order_by_expr, expected))
            return false;