only parse and not modify statement

Author: aleksei.p

src/parser/mod.rs

@@ -5392,7 +5392,7 @@ impl<'a> Parser<'a> {
 
     pub fn parse_column_def(&mut self) -> Result<ColumnDef, ParserError> {
         let name = self.parse_identifier(false)?;
-        let mut data_type = if self.is_column_type_sqlite_unspecified() {
+        let data_type = if self.is_column_type_sqlite_unspecified() {
             DataType::Unspecified
         } else {
             self.parse_data_type()?
@@ -5424,16 +5424,6 @@ impl<'a> Parser<'a> {
                 break;
             };
         }
-        // ClickHouse represents a special NULL marker as a data type Nullable
-        // https://clickhouse.com/docs/en/sql-reference/data-types/nullable
-        if dialect_of!(self is ClickHouseDialect)
-            && options
-                .iter()
-                .any(|o| matches!(o.option, ColumnOption::Null))
-        {
-            data_type = DataType::Nullable(Box::new(data_type));
-            options.retain(|o| !matches!(o.option, ColumnOption::Null));
-        }
         Ok(ColumnDef {
             name,
             data_type,

tests/sqlparser_clickhouse.rs

@@ -223,9 +223,10 @@ fn parse_create_table() {
 #[test]
 fn parse_create_table_with_nullable() {
     let sql = r#"CREATE TABLE table (k UInt8, `a` Nullable(String), `b` Nullable(DateTime64(9, 'UTC')), c Nullable(DateTime64(9)), d Date32 NULL) ENGINE=MergeTree ORDER BY (`k`)"#;
-    let canonical_sql = r#"CREATE TABLE table (k UInt8, `a` Nullable(STRING), `b` Nullable(DateTime64(9, 'UTC')), c Nullable(DateTime64(9)), d Nullable(Date32)) ENGINE=MergeTree ORDER BY (`k`)"#;
+    // ClickHouse has a case-sensitive definition of data type, but canonical representation is not
+    let canonical_sql = sql.replace("String", "STRING");
 
-    match clickhouse().one_statement_parses_to(sql, canonical_sql) {
+    match clickhouse().one_statement_parses_to(sql, &canonical_sql) {
         Statement::CreateTable { name, columns, .. } => {
             assert_eq!(name, ObjectName(vec!["table".into()]));
             assert_eq!(
@@ -260,9 +261,11 @@ fn parse_create_table_with_nullable() {
                     },
                     ColumnDef {
                         name: Ident::new("d"),
-                        data_type: DataType::Nullable(Box::new(DataType::Date32)),
+                        data_type: DataType::Date32,
                         collation: None,
-                        options: vec![],
+                        options: vec![
+                            ColumnOptionDef{name: None, option: ColumnOption::Null}
+                        ],
                     },
                 ]
             );