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Support EXTRACT function-like operator

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The EXTRACT function, for extracting components of a date from a
timestamp, has special syntax: `EXTRACT(<field> FROM <timestamp>)`.
This commit is contained in:
Nikhil Benesch 2019-05-30 01:38:02 -04:00
parent 2f4cd8f6c8
commit d484756182
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3 changed files with 85 additions and 0 deletions
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26
src/sqlparser.rs
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@ -193,6 +193,7 @@ impl Parser {
"CASE" => self.parse_case_expression(),
"CAST" => self.parse_cast_expression(),
"EXISTS" => self.parse_exists_expression(),
"EXTRACT" => self.parse_extract_expression(),
"NOT" => Ok(ASTNode::SQLUnary {
operator: SQLOperator::Not,
expr: Box::new(self.parse_subexpr(Self::UNARY_NOT_PREC)?),
@ -417,6 +418,31 @@ impl Parser {
Ok(exists_node)
}
pub fn parse_extract_expression(&mut self) -> Result<ASTNode, ParserError> {
self.expect_token(&Token::LParen)?;
let tok = self.next_token();
let field = if let Some(Token::SQLWord(ref k)) = tok {
match k.keyword.as_ref() {
"YEAR" => SQLDateTimeField::Year,
"MONTH" => SQLDateTimeField::Month,
"DAY" => SQLDateTimeField::Day,
"HOUR" => SQLDateTimeField::Hour,
"MINUTE" => SQLDateTimeField::Minute,
"SECOND" => SQLDateTimeField::Second,
_ => self.expected("Date/time field inside of EXTRACT function", tok)?,
}
} else {
self.expected("Date/time field inside of EXTRACT function", tok)?
};
self.expect_keyword("FROM")?;
let expr = self.parse_expr()?;
self.expect_token(&Token::RParen)?;
Ok(ASTNode::SQLExtract {
field,
expr: Box::new(expr),
})
}
/// Parse an operator following an expression
pub fn parse_infix(&mut self, expr: ASTNode, precedence: u8) -> Result<ASTNode, ParserError> {
debug!("parsing infix");