Sampling method

Dear Experts,
What is the sampling method that can be used to select a daily sample (in-patient medical records) from a population divided into 22 departments, e.g. oncology, pediatric, …, etc?
The number of medical records varies from department to department.
I want to select the sample in a daily basis, can I use the stratified method and if it is stratified method, is it proportions stratified sample?
Many thanks in advance.
D. Salmain.
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