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Support DISTINCT ON (...) (#852)

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* Support "DISTINCT ON (...)"

* a test

* fix the merge
This commit is contained in:
Aljaž Mur Eržen 2023-04-27 21:34:54 +02:00 • committed by GitHub
parent f72e2ec382
commit 3b1076c194
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7 changed files with 96 additions and 31 deletions
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33
src/parser.rs
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@ -879,7 +879,7 @@ impl<'a> Parser<'a> {
pub fn parse_function(&mut self, name: ObjectName) -> Result<Expr, ParserError> {
self.expect_token(&Token::LParen)?;
let distinct = self.parse_all_or_distinct()?;
let distinct = self.parse_all_or_distinct()?.is_some();
let args = self.parse_optional_args()?;
let over = if self.parse_keyword(Keyword::OVER) {
// TBD: support window names (`OVER mywin`) in place of inline specification
@ -1302,7 +1302,7 @@ impl<'a> Parser<'a> {
/// Parse a SQL LISTAGG expression, e.g. `LISTAGG(...) WITHIN GROUP (ORDER BY ...)`.
pub fn parse_listagg_expr(&mut self) -> Result<Expr, ParserError> {
self.expect_token(&Token::LParen)?;
let distinct = self.parse_all_or_distinct()?;
let distinct = self.parse_all_or_distinct()?.is_some();
let expr = Box::new(self.parse_expr()?);
// While ANSI SQL would would require the separator, Redshift makes this optional. Here we
// choose to make the separator optional as this provides the more general implementation.
@ -2300,16 +2300,31 @@ impl<'a> Parser<'a> {
}
}
/// Parse either `ALL` or `DISTINCT`. Returns `true` if `DISTINCT` is parsed and results in a
/// `ParserError` if both `ALL` and `DISTINCT` are fround.
pub fn parse_all_or_distinct(&mut self) -> Result<bool, ParserError> {
/// Parse either `ALL`, `DISTINCT` or `DISTINCT ON (...)`. Returns `None` if `ALL` is parsed
/// and results in a `ParserError` if both `ALL` and `DISTINCT` are found.
pub fn parse_all_or_distinct(&mut self) -> Result<Option<Distinct>, ParserError> {
let all = self.parse_keyword(Keyword::ALL);
let distinct = self.parse_keyword(Keyword::DISTINCT);
if all && distinct {
parser_err!("Cannot specify both ALL and DISTINCT".to_string())
} else {
Ok(distinct)
if !distinct {
return Ok(None);
}
if all {
return parser_err!("Cannot specify both ALL and DISTINCT".to_string());
}
let on = self.parse_keyword(Keyword::ON);
if !on {
return Ok(Some(Distinct::Distinct));
}
self.expect_token(&Token::LParen)?;
let col_names = if self.consume_token(&Token::RParen) {
self.prev_token();
Vec::new()
} else {
self.parse_comma_separated(Parser::parse_expr)?
};
self.expect_token(&Token::RParen)?;
Ok(Some(Distinct::On(col_names)))
}
/// Parse a SQL CREATE statement