[Bug]: "ALTER TABLE" can collect entities but entities don't have belongStmt

[Kijin-Seija]

Version

4.0.1

Which SQL?

Postgre

SQL content

ALTER TABLE my_table DROP a_column|;

JavaScript/TypeScript code

No response

What happened?

my_table can be collected but it has no belongStmt, then people cannot use isContainCaret or other properities

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my_table被收集了但是其属性里没有belongStmt, 基于isContainCaret或其他StmtContext属性的功能可能会无法正常工作。

I find that maybe there's no definition of altertablestmt. I will create a PR and try to cover it. If there is already a roadmap, ignore the PR.

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看了下好像是没有定义'altertablestmt'这个StmtContext，我这边尝试添加了一下，已测试通过。如果这在你们的roadmap上，请忽略此PR

Relevant log output

No response