Method parse_select

src/sql-parser/src/parser.rs:7813–7913

Parse a restricted `SELECT` statement (no CTEs / `UNION` / `ORDER BY`), assuming the initial `SELECT` was already consumed

(&mut self)

    /// Parse a restricted `SELECT` statement (no CTEs / `UNION` / `ORDER BY`),
    /// assuming the initial `SELECT` was already consumed
    fn parse_select(&mut self) -> Result<Select<Raw>, ParserError> {
        let all = self.parse_keyword(ALL);
        let distinct = self.parse_keyword(DISTINCT);
        if all && distinct {
            return parser_err!(
                self,
                self.peek_prev_pos(),
                "Cannot specify both ALL and DISTINCT in SELECT"
            );
        }
        let distinct = if distinct && self.parse_keyword(ON) {
            self.expect_token(&Token::LParen)?;
            let exprs = self.parse_comma_separated(Parser::parse_expr)?;
            self.expect_token(&Token::RParen)?;
            Some(Distinct::On(exprs))
        } else if distinct {
            Some(Distinct::EntireRow)
        } else {
            None
        };

        let projection = match self.peek_token() {
            // An empty target list is permissible to match PostgreSQL, which
            // permits these for symmetry with zero column tables. We need
            // to sniff out `AS` here specially to support `SELECT AS OF ...`.
            Some(Token::Keyword(kw)) if kw.is_always_reserved() || kw == AS => vec![],
            Some(Token::Semicolon) | Some(Token::RParen) | None => vec![],
            _ => {
                let mut projection = vec![];
                loop {
                    projection.push(self.parse_select_item()?);
                    if !self.consume_token(&Token::Comma) {
                        break;
                    }
                    if self.peek_keyword(FROM) {
                        return parser_err!(
                            self,
                            self.peek_prev_pos(),
                            "invalid trailing comma in SELECT list",
                        );
                    }
                }
                projection
            }
        };

        // Note that for keywords to be properly handled here, they need to be
        // added to `RESERVED_FOR_COLUMN_ALIAS` / `RESERVED_FOR_TABLE_ALIAS`,
        // otherwise they may be parsed as an alias as part of the `projection`
        // or `from`.

        let from = if self.parse_keyword(FROM) {
            self.parse_comma_separated(Parser::parse_table_and_joins)?
        } else {
            vec![]
        };

        let selection = if self.parse_keyword(WHERE) {