Support SELECT DISTINCT

src/sqlast/query.rs

@@ -110,6 +110,7 @@ impl ToString for SQLSetOperator {
 /// to a set operation like `UNION`.
 #[derive(Debug, Clone, PartialEq)]
 pub struct SQLSelect {
+    pub distinct: bool,
     /// projection expressions
     pub projection: Vec<SQLSelectItem>,
     /// FROM
@@ -127,7 +128,8 @@ pub struct SQLSelect {
 impl ToString for SQLSelect {
     fn to_string(&self) -> String {
         let mut s = format!(
-            "SELECT {}",
+            "SELECT{} {}",
+            if self.distinct { " DISTINCT" } else { "" },
             self.projection
                 .iter()
                 .map(|p| p.to_string())

src/sqlparser.rs

@@ -1352,6 +1352,7 @@ impl Parser {
     /// Parse a restricted `SELECT` statement (no CTEs / `UNION` / `ORDER BY`),
     /// assuming the initial `SELECT` was already consumed
     pub fn parse_select(&mut self) -> Result<SQLSelect, ParserError> {
+        let distinct = self.parse_keyword("DISTINCT");
         let projection = self.parse_select_list()?;
 
         let (relation, joins) = if self.parse_keyword("FROM") {
@@ -1381,6 +1382,7 @@ impl Parser {
         };
 
         Ok(SQLSelect {
+            distinct,
             projection,
             selection,
             relation,

tests/sqlparser_generic.rs

@@ -50,11 +50,23 @@ fn parse_where_delete_statement() {
 fn parse_simple_select() {
     let sql = "SELECT id, fname, lname FROM customer WHERE id = 1 LIMIT 5";
     let select = verified_only_select(sql);
+    assert_eq!(false, select.distinct);
     assert_eq!(3, select.projection.len());
     let select = verified_query(sql);
     assert_eq!(Some(ASTNode::SQLValue(Value::Long(5))), select.limit);
 }
 
+#[test]
+fn parse_select_distinct() {
+    let sql = "SELECT DISTINCT name FROM customer";
+    let select = verified_only_select(sql);
+    assert_eq!(true, select.distinct);
+    assert_eq!(
+        &SQLSelectItem::UnnamedExpression(ASTNode::SQLIdentifier("name".to_string())),
+        only(&select.projection)
+    );
+}
+
 #[test]
 fn parse_select_wildcard() {
     let sql = "SELECT * FROM foo";