Why can't I delete data?

I just want to query this page and delete a piece of data on this page. now I can query it, but I cannot delete it. what is wrong? {Code...} is to query and delete a piece of data on this page. it can be queried now, but it cannot be deleted. what is wrong?

 


  Exec ($ SQL);?>

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I just want to query this page and delete a piece of data on this page. now I can query it, but I cannot delete it. what is wrong?

 


  Exec ($ SQL);?>

First, echo your delete SQL to see if it is the expected result.
Then go to the database for execution to see if there is any effect.
There are still problems.

$ Cm is written as '{$ cm }'

There is no input field in your deletion, and no value is submitted to the form, so there is nothing to delete