创建索引问题

```
问下wasp 创建索引的语法是什么，在wasp shell中测试一直创建不了，命令：
```

wasp(main):002:0>sql "create index PhotosByTime on Photo(user_id,time desc);"

Reproduce the `create index PhotosByTime on Photo(user_id,time desc);` command in the Wasp shell and inspect how index-creation statements are handled. Determine whether the syntax is unsupported or failing unexpectedly; done means the supported syntax or the required behavior is documented and the command works as intended.

Written by the indexing model from the issue text.