We have been writing TSQL codes for a long time but do you know what type of language TSQL is? It is unknown to many or many know the type of it but do not know what does it mean.
TSQL is a Declarative Language because the TSQL statement that describes the logic does not describe the sequence of execution of individual elements in the statement for processing the logic. If you have written a TSQL statement, it is not necessary to process the individual clauses in the statement as they appear in the statement. That is how it works and that is why TSQL becomes a Declarative Language. However there are exceptions as well. TSQL has some Imperative Language flavors because it supports statements like WHILE, IF THEN.
The other type, Imperative Language processes the logic as they appear, as they are written. The languages like .NET, C++ are examples for Imperative Languages and commands written are executed in the sequence they appear.
Read more on Imperative Language at: https://en.wikipedia.org/wiki/Imperative_programming
Read more on Declarative Language at: https://en.wikipedia.org/wiki/Declarative_programming