Merge pull request #2496 from weartist/patch-1

Update sql.md

Author: kamilmysliwiec

content/techniques/sql.md

@@ -180,7 +180,7 @@ export class UsersService {
     return this.usersRepository.find();
   }
 
-  findOne(id: string): Promise<User> {
+  findOne(id: number): Promise<User> {
     return this.usersRepository.findOneBy({ id });
   }