Allow IF NOT EXISTS after table name for Snowflake (apache#1881)

Author: bombsimon

src/dialect/snowflake.rs

@@ -560,6 +560,9 @@ pub fn parse_create_table(
                     builder.storage_serialization_policy =
                         Some(parse_storage_serialization_policy(parser)?);
                 }
+                Keyword::IF if parser.parse_keywords(&[Keyword::NOT, Keyword::EXISTS]) => {
+                    builder = builder.if_not_exists(true);
+                }
                 _ => {
                     return parser.expected("end of statement", next_token);
                 }

tests/sqlparser_snowflake.rs

@@ -446,6 +446,27 @@ fn test_snowflake_create_table_if_not_exists() {
         }
         _ => unreachable!(),
     }
+
+    for (sql, parse_to) in [
+        (
+            r#"CREATE TABLE IF NOT EXISTS "A"."B"."C" (v VARIANT)"#,
+            r#"CREATE TABLE IF NOT EXISTS "A"."B"."C" (v VARIANT)"#,
+        ),
+        (
+            r#"CREATE TABLE "A"."B"."C" IF NOT EXISTS (v VARIANT)"#,
+            r#"CREATE TABLE IF NOT EXISTS "A"."B"."C" (v VARIANT)"#,
+        ),
+        (
+            r#"CREATE TRANSIENT TABLE IF NOT EXISTS "A"."B"."C" (v VARIANT)"#,
+            r#"CREATE TRANSIENT TABLE IF NOT EXISTS "A"."B"."C" (v VARIANT)"#,
+        ),
+        (
+            r#"CREATE TRANSIENT TABLE "A"."B"."C" IF NOT EXISTS (v VARIANT)"#,
+            r#"CREATE TRANSIENT TABLE IF NOT EXISTS "A"."B"."C" (v VARIANT)"#,
+        ),
+    ] {
+        snowflake().one_statement_parses_to(sql, parse_to);
+    }
 }
 
 #[test]