How to query multiple tables in the tp framework

For example, two tables, apply and activityapply, have the openid field and the idac_id of activity. Now we need to query openid and all records with openid in the apply table. How can we write an SQL statement, for example, two tables? the openid and activity id ac_id fields in the apply and activity apply tables now need to be queried in the apply table and all records with openid in the activity table. How can I write an SQL statement?

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For example, the openid and activity id ac_id fields in the apply and activity apply tables of two tables need to be queried in the apply table and all records with openid in the activity table. How can I write an SQL statement?

M ('application')-> field ('a. openid, ac. * ')-> alias ('A')-> join (' _ ACTIVITY _ ac ON. ac_id = ac. id')-> select ();

That's what it means.

If you want an SQL statement, it has nothing to do with the framework. For example, a box is added with the same SQL statement,
If you are asking how to define the model change in tp, see the view model section in the official documentation for details.