A parameter query is one where, the user supplies criteria with which to filter the results.
When you run a normal query, it will return its results as soon as you run it.
When you run a parameter query, it asks you to enter a value. Once you provide the value, it will continue running, using the value as part of the filtering criteria.
The parameter is provided by the user at runtime. So a parameter query can return different results based on the user's input.
Dates are common parameters in parameter queries. This allows the user to provide a date with which to search. Numbers are also common parameters.
Parameter Query vs a Normal Query
There's almost no difference between creating parameter queries and normal queries. The only difference is that you use square brackets [] to display text to the user.
For example:
Will result in this prompt when the user runs the query:
In this example, the date provided will be used to filter the results in the query to only those albums released after the date provided (because the query has a greater than sign > before the prompt).
Here's a step-by-step guide to creating a parameter query.