From your question, I understand that you want to get statistics regarding the number of transactions per second (TPS). These are standard statistics about the capabilities of your computer infrastructure and database servers. If I understood correctly, this mathematical formula could help.
TPS = number of transactions / amount (each transaction time in seconds)
This will let you know how many transactions per second looked into your server over the elapsed time (period of the DateTime interval)
On the other hand, if you want to calculate the server load based on the number of users and then simulate it, you might want to find specialized loadTest tools.
Let me know if I answer your question correctly or let me know what I missed in your question.
EDIT 1 :
EDIT 2 : QaLoad de Microfocus
JAVA-: Apache JMeter
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