Update 02-random.md

Author: BohuTANG

docs/doc/13-sql-reference/30-table-engines/02-random.md

@@ -18,7 +18,7 @@ Random engine is used to generate random data for testing purposes. If limit is
 
 Example:
 
-```
+```sql
 > create table r (a int, b timestamp, c String, d Variant) Engine = Random;
 
 > select * from r limit 3;