revise #4577, cannot use rule in lexer (#4730)

shardingsphere-sql-parser/shardingsphere-sql-parser-dialect/shardingsphere-sql-parser-sqlserver/src/main/antlr4/imports/sqlserver/BaseRule.g4

@@ -95,7 +95,7 @@ unreservedWord
     | MESSAGE | TYPE | REMOTE | BINDING | ROUTE | SECURITY | POLICY | AGGREGATE | QUEUE
     | RULE | SYNONYM | COLLECTION | SCRIPT | KILL | BACKUP | LOG | SHOWPLAN
     | SUBSCRIBE | QUERY | NOTIFICATIONS | CHECKPOINT | SEQUENCE | INSTANCE | DO | DEFINER | LOCAL | CASCADED
-    | NEXT | NAME | INTEGER | TYPE | MAX | MIN | SUM | COUNT | AVG | FIRST
+    | NEXT | NAME | INTEGER | TYPE | MAX | MIN | SUM | COUNT | AVG | FIRST | DATETIME2
     ;
 
 schemaName
@@ -281,7 +281,7 @@ dataType
 
 dataTypeName
     : BIGINT | NUMERIC | BIT | SMALLINT | DECIMAL | SMALLMONEY | INT | TINYINT | MONEY | FLOAT | REAL
-    | DATE | DATETIMEOFFSET | SMALLDATETIME | DATETIME | TIME | CHAR | VARCHAR | TEXT | NCHAR | NVARCHAR
+    | DATE | DATETIMEOFFSET | SMALLDATETIME | DATETIME | DATETIME2 | TIME | CHAR | VARCHAR | TEXT | NCHAR | NVARCHAR
     | NTEXT | BINARY | VARBINARY | IMAGE | SQL_VARIANT | XML | UNIQUEIDENTIFIER | HIERARCHYID | GEOMETRY
     | GEOGRAPHY | IDENTIFIER_
     ;

shardingsphere-sql-parser/shardingsphere-sql-parser-dialect/shardingsphere-sql-parser-sqlserver/src/main/antlr4/imports/sqlserver/SQLServerKeyword.g4

@@ -868,7 +868,11 @@ DATETIMEOFFSET
     ;
 
 DATETIME
-    : D A T E T I M E [2]?
+    : D A T E T I M E
+    ;
+
+DATETIME2
+    : D A T E T I M E [2]
     ;
 
 SMALLDATETIME