Support Unload statement (#1150)

Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>

src/ast/mod.rs

@@ -2547,6 +2547,16 @@ pub enum Statement {
     /// ```
     /// Note: this is a MySQL-specific statement. See <https://dev.mysql.com/doc/refman/8.0/en/lock-tables.html>
     UnlockTables,
+    /// ```sql
+    /// UNLOAD(statement) TO <destination> [ WITH options ]
+    /// ```
+    /// See Redshift <https://docs.aws.amazon.com/redshift/latest/dg/r_UNLOAD.html> and
+    // Athena <https://docs.aws.amazon.com/athena/latest/ug/unload.html>
+    Unload {
+        query: Box<Query>,
+        to: Ident,
+        with: Vec<SqlOption>,
+    },
 }
 
 impl fmt::Display for Statement {
@@ -4060,6 +4070,15 @@ impl fmt::Display for Statement {
             Statement::UnlockTables => {
                 write!(f, "UNLOCK TABLES")
             }
+            Statement::Unload { query, to, with } => {
+                write!(f, "UNLOAD({query}) TO {to}")?;
+
+                if !with.is_empty() {
+                    write!(f, " WITH ({})", display_comma_separated(with))?;
+                }
+
+                Ok(())
+            }
         }
     }
 }

src/keywords.rs

@@ -689,6 +689,7 @@ define_keywords!(
     UNION,
     UNIQUE,
     UNKNOWN,
+    UNLOAD,
     UNLOCK,
     UNLOGGED,
     UNNEST,

src/parser/mod.rs

@@ -516,6 +516,7 @@ impl<'a> Parser<'a> {
                 Keyword::MERGE => Ok(self.parse_merge()?),
                 // `PRAGMA` is sqlite specific https://www.sqlite.org/pragma.html
                 Keyword::PRAGMA => Ok(self.parse_pragma()?),
+                Keyword::UNLOAD => Ok(self.parse_unload()?),
                 // `INSTALL` is duckdb specific https://duckdb.org/docs/extensions/overview
                 Keyword::INSTALL if dialect_of!(self is DuckDbDialect | GenericDialect) => {
                     Ok(self.parse_install()?)
@@ -524,7 +525,6 @@ impl<'a> Parser<'a> {
                 Keyword::LOAD if dialect_of!(self is DuckDbDialect | GenericDialect) => {
                     Ok(self.parse_load()?)
                 }
-
                 _ => self.expected("an SQL statement", next_token),
             },
             Token::LParen => {
@@ -8947,6 +8947,23 @@ impl<'a> Parser<'a> {
         })
     }
 
+    pub fn parse_unload(&mut self) -> Result<Statement, ParserError> {
+        self.expect_token(&Token::LParen)?;
+        let query = self.parse_query()?;
+        self.expect_token(&Token::RParen)?;
+
+        self.expect_keyword(Keyword::TO)?;
+        let to = self.parse_identifier(false)?;
+
+        let with_options = self.parse_options(Keyword::WITH)?;
+
+        Ok(Statement::Unload {
+            query: Box::new(query),
+            to,
+            with: with_options,
+        })
+    }
+
     pub fn parse_merge_clauses(&mut self) -> Result<Vec<MergeClause>, ParserError> {
         let mut clauses: Vec<MergeClause> = vec![];
         loop {