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feat: support multi value column unpivot & alias in unpivot #1969

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for example, spark supports

SELECT * FROM sales_quarterly
    UNPIVOT EXCLUDE NULLS (
        (first_quarter, second_quarter)
        FOR half_of_the_year IN (
            (q1, q2) AS H1,
            (q3, q4) AS H2
        )
    );

https://spark.apache.org/docs/latest/sql-ref-syntax-qry-select-unpivot.html

@chenkovsky chenkovsky changed the title feat: support multi value column unpivot feat: support multi value column unpivot & alias in unpivot Jul 23, 2025
src/ast/query.rs Outdated
@@ -1351,9 +1392,9 @@ pub enum TableFactor {
/// See <https://docs.snowflake.com/en/sql-reference/constructs/unpivot>.
Unpivot {
table: Box<TableFactor>,
value: Ident,
value: Vec<Ident>,
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should we use expr::Identifier ? otherwise we cannot visit this ident by vistor.

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Hmm yeah I think repr wise we could represent this as an arbitrary Expr, it would cover both the single_value and multi_value scenarios. Then similarly, we change to columns: Vec<ExprWithAlias>, which would additionally cover the fully qualified column_name variant

Comment on lines 11027 to 11029
"SELECT * FROM sales AS s ",
"UNPIVOT INCLUDE NULLS (quantity FOR quarter IN (Q1 AS Quater1, Q2 AS Quater2, Q3 AS Quater3, Q4 AS Quater4)) AS u (product, quarter, quantity)"
);
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it look like the formatting is a bit off here with cargo fmt, could you manually unindent these lines?

sql_unpivot_with_alias
);

let sql_unpivot_with_alias = concat!(
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this has the same name as the preceeding sql_unpivot_with_alias scenario, but testing different aspects, do we need to rename this accordingly?

src/ast/query.rs Outdated
@@ -1351,9 +1392,9 @@ pub enum TableFactor {
/// See <https://docs.snowflake.com/en/sql-reference/constructs/unpivot>.
Unpivot {
table: Box<TableFactor>,
value: Ident,
value: Vec<Ident>,
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Hmm yeah I think repr wise we could represent this as an arbitrary Expr, it would cover both the single_value and multi_value scenarios. Then similarly, we change to columns: Vec<ExprWithAlias>, which would additionally cover the fully qualified column_name variant

@@ -1351,9 +1392,9 @@ pub enum TableFactor {
/// See <https://docs.snowflake.com/en/sql-reference/constructs/unpivot>.
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Can we include the link to the databricks documentation here as well?

Comment on lines +13895 to +13908
let value = match self.peek_token_ref().token {
Token::LParen => {
// multi value column unpivot
Expr::Tuple(
self.parse_parenthesized_column_list(Mandatory, false)?
.into_iter()
.map(Expr::Identifier)
.collect(),
)
}
_ => {
// single value column unpivot
Expr::Identifier(self.parse_identifier()?)
}
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Can we call self.parse_expr() and self.parse_expr_with_alias() transparently instead?

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2 participants