Working on a database priorly designed and maintained by some private agency.

The fuck I'm dealing with!

Boolean values stored as 'TRUE'/'FALSE'. It's varchar, my dudes.

There are no FK relations. Just the values of IDs in a column.

There are no indexes, all on just the PKs, nothing else. Nothing.

Null, what's that? I'm dealing with 'N/A', my dudes.

Unique key, what's that? The table which stores users has all the fields nullable. Email is not unique ( even though that's the required behaviour).

ALL the numeric values are stored as varchar. Varchar, my dudes. Varchar. '1', '1.1'

And finally, the good ole, 1 table to rule them all. Normalisation, fuck that.

And what's the root cause of all this? My PM used to hand them Excel sheets she maintains on her local system. FTW. I don't have a enough explanations.

When your project manager promised to give you a script generator for the big database migration and came back with an Excel sheet where you have to copy-paste every table name and fields to get the table specific part of the script.
Damn copy-pasting programmation ...