使用交叉引用的行复制MySQL中的数据

I'm not a database expert, so I'm not sure how to ask this question briefly and succinctly. I am trying to copy data with the following characteristics: many of the tables with data being copied contain references to other tables with data being copied; i.e., a patient might attend a class where their weight is recorded, so I need to copy both the class attendance row as well as the weight value stored in another table, which is referenced by the class attendance row. There are other, even more complex, examples in this database, but it seems that I need to perform some kind of recursive copy of these inter-referenced items so I can maintain the cross-references in the copied data.

So, is there any kind of standard approach to this problem? If there isn't a direct answer, could someone share the terminology of what I'm trying to do so that I can look it up on my own? I'm certain this problem has been tackled many times before, but I don't know how to find the solution. I understand the basic concepts of JOINs and FKs, but this solution seems to require a way to copy the rows from various tables while also going back and updating the cross-references (in some cases, these are FKs, and in other cases, they are not; I'm stuck with the schema as it is).

PS: If it's such an obvious solution, why won't anyone just provide it or characterize it below so we can move on? Most of humanity is capable of asking the occasional dumb question, and this may very well be one of mine, but I'm seriously stuck on this one and would appreciate some assistance.

Here's a sketch of a small part of the schema to try to illustrate the issue:

When we copy a patient's data record, we need to 1) create a new row in patient; 2) create a corresponding new row in edclass_session_labs; 3) create a new row in patient_lab_weight; and (here's what I see as the tricky part) 4) also update the reference in edclass_session_labs to the new row in patient_lab_weight. What I'm looking for is a way to do this programmatically and algorithmically. I'm sure problems like this have been tackled before, so that's why I'm asking for advice here.

I didn't fully understand what you mean by "copy patient data", so there are two options:

1) If you want to "copy" the data to a report, you need to link many tables with related information, so you have to study the concept of JOINs and FOREIGN KEYs. This is what we do when we need to convert relational data into a flat table that can be easily read by non-IT people.

2) If you need to copy specific data from database tables to other database tables, you also have to study FOREIGN KEYs and table relationship. You need to understand how table rows relate to rows on other tables (one to many, many to one, many to many), so you can create INSERT statements based on SELECTs that will filter the exact data you need.

This is very general, but I think it's sufficient to point you to the right direction.

EDIT:

Since the issue is related to creating a merged structure of patient data, let's say we have patient 1 and patient 2. They are duplicates of the same person, and need to be merged. I would do this, in this order:

a) Create a patient 3, this one will be the target of our merging. Simply copy each field from patients 1 or 2 to this new record.

b) Create as many new records as needed in table "patient_lab_weight". For example: if patient 1 has 2 records there, and patient 2 has 4 records, you will have to create 6 records, which are copies of the records related to patient 1 and 2, but patient_id will be 3. However, after creating each record here, obtain the auto_increment generated for field "patient_lab_weight_id", and insert a new record in "ed_class_session_labs", with patient_id = 3, and "patient_lab_weight_id" = the obtained ID. Do that for each insert on "patient_lab_weight".

c) after all that, disable patients 1 and 2 in your application.

If you use this approach, you will slowly build up your new structure, linked in a consistent way.