Matching (querying?) criteria with IMPORTRANGE - google-sheets-formula

Question

Forgive me if I am not using the correct terminology, I short of crash-coursed myself in Google sheets a few days ago.
Is there a way that I could using IMPORTRANGE to import a data range from spreadsheet 2 into spreadsheet 1, where the range selected from spreadsheet 2 can be matched against criteria in spreadsheet 1 that corresponds to criteria in spreadsheet 2? I have a specific set of data in spreadsheet 1 that, while the same in content, is not in the same order as spreadsheet 2 (which I don't myself maintain) or spreadsheet 3 (which is maintained by someone other than myself or the person that maintains spreadsheet 2), but am being given access to spreadsheet 2 and spreadsheet 3 data that I didn't previously have.
EXAMPLE:
https://docs.google.com/spreadsheets/d/1ByN9Ju8QiiHTfFgow7lDF4VN-zBRqP1gzpAK73ZRBNg/edit?usp=sharing

Answer 1

You work with IMPORTRANGE content the same way as you do with any range within your spreadsheet. Good practice is to use columns with unique content as ID's for searching, filtering, etc.
If you want put the content of somebody's spreadsheet into yours, you can control it.
For example:
In order to get REGISTRATION number from sheet3
Think of VLOOKUP construction:
=VLOOKUP(key,table with key value on the leftmost column;number of column to take value from,false)
You use vlookup formula that takes name in your table as a key (first parameter of formula), then you must rebuild your importrange to have key in leftmost column.
2nd parameter of VLOOKUP will look like this:
{importrange("Sheet3url";"Sheet!Columnwithname"),importrange("Sheet3url";"Sheet!Columnwithregistration")}
This is your temporary table made of 2 importranges.
You want 2nd column of this construction - which is column with registration.
Whole vlookup looks like this:
=VLOOKUP(key,{importrange("Sheet3url";"Sheet!Columnwithname"),importrange("Sheet3url";"Sheet!Columnwithregistration")},2,false)
It's much easier when key is on the left. If you want to extract SEX and DOB you use:
=VLOOKUP(key,importrange("Sheet3url";"Sheet!Columnsfromname to DOB"),2 and then 3,false)
Beware - using multiple importrange makes your sheet slow.
If you have hundreds of rows, you should wrap it around with arrayformula to work with all rows in one go.
Also you can first importrange somebodys table into your sheet on a side and operate inside your sheet.
It's advised when using big datasets and not that many files.