Enable parsing CREATE FUNCTION without AS

Author: aharpervc

src/parser/mod.rs

@@ -5230,7 +5230,9 @@ impl<'a> Parser<'a> {
             Some(self.parse_data_type()?)
         };
 
-        self.expect_keyword_is(Keyword::AS)?;
+        if self.peek_keyword(Keyword::AS) {
+            self.expect_keyword_is(Keyword::AS)?;
+        }
 
         let function_body = if self.peek_keyword(Keyword::BEGIN) {
             let begin_token = self.expect_keyword(Keyword::BEGIN)?;
@@ -9819,7 +9821,7 @@ impl<'a> Parser<'a> {
                     Ok(DataType::AnyType)
                 }
                 Keyword::TABLE => {
-                    if self.peek_keyword(Keyword::AS) {
+                    if self.peek_token() != Token::LParen {
                         Ok(DataType::Table(Vec::<ColumnDef>::new()))
                     } else {
                         let columns = self.parse_returns_table_columns()?;

tests/sqlparser_mssql.rs

@@ -254,6 +254,12 @@ fn parse_create_function() {
     ";
     let _ = ms().verified_stmt(multi_statement_function);
 
+    let multi_statement_function_without_as = multi_statement_function.replace(" AS", "");
+    let _ = ms().one_statement_parses_to(
+        &multi_statement_function_without_as,
+        multi_statement_function,
+    );
+
     let create_function_with_conditional = "\
         CREATE FUNCTION some_scalar_udf() \
         RETURNS INT \
@@ -297,6 +303,13 @@ fn parse_create_function() {
     ";
     let _ = ms().verified_stmt(create_inline_table_value_function);
 
+    let create_inline_table_value_function_without_as =
+        create_inline_table_value_function.replace(" AS", "");
+    let _ = ms().one_statement_parses_to(
+        &create_inline_table_value_function_without_as,
+        create_inline_table_value_function,
+    );
+
     let create_multi_statement_table_value_function = "\
         CREATE FUNCTION some_multi_statement_tvf(@foo INT, @bar VARCHAR(256)) \
         RETURNS @t TABLE (col_1 INT) \
@@ -307,6 +320,13 @@ fn parse_create_function() {
         END\
     ";
     let _ = ms().verified_stmt(create_multi_statement_table_value_function);
+
+    let create_multi_statement_table_value_function_without_as =
+        create_multi_statement_table_value_function.replace(" AS", "");
+    let _ = ms().one_statement_parses_to(
+        &create_multi_statement_table_value_function_without_as,
+        create_multi_statement_table_value_function,
+    );
 }
 
 #[test]