What is ad hoc in SQL?
In SQL, an ad hoc query is a loosely entered command / query whose value depends on a variable. Each time the command is executed, the result is different depending on the value of the variable. It cannot be predetermined and usually comes under dynamic programming SQL query. An ad hoc query is short-lived and is created at runtime.
As the word 'ad hoc' suggests, this type of query is designed for a 'specific purpose', which is in contrast to a predefined query that has the same output value every time it is executed. An ad hoc query does not stay in the system for long and is created dynamically by the user if necessary. It is more efficient to use an ad hoc query when programming because it saves system resources. At the same time, complex ad hoc queries (with multiple variables) also call into question the processing speed and the runtime memory of the system.
English 
German 