What are queries? (in databases)?

Question

if u know, could u name some? thank u

Answer 1

Basically, any message sent to the database such as a select or insert.

Answer 2

The main purpose of creating/designing a database is to be able to extract information from it. The way you extract information is to set up queries.A query is usually based on the table or tables, or could be based on a query itself, to pull out certain information that is contained in the table. For instance, you may have a customer database with names, addresses etc. You want to do a mailing to all your customers, but as you have over 1,000 you are going to phase it in groups by post code. You would therefore enter the criteria you are looking for in the postcode field, for instance W1A 1NN and run the query and you would be given only those customers who were located in that postcode area. you can search for anything, pull out people between a certain age, those who earn a salary above a certain amount, below a certain amount. Whatever you want to find out, provided the data is in the database, you can extract it. Once you have got the results of your query you would probably design a report from it so that the data appears in more aesthetically pleasing format.

Answer 3

A query is an order to fetch a bit of information. For example, in a database containing names, addresses, ages, phone numbers, a query might be a fetch of "Herbert Hoover" and the database routine might search through the database to find Herbert. Or a query might be, to find all entries on "Elm Street" and yield an array of that set of entries.

Answer 4

A query is a statement which manipulates data. Basically it asks a question which is answered by presenting the data requested.

The main types are
Select query (selects data using filters & logical criteria)
Update query (modifies data by applying filters & logical criteria)
Delete, Append & make-table queries (self-explanatory)

A rudimentary query is "Which customers live in Surrey?" You have a table full of customers with their addresses, and your query filters out all those who don't live in Surrey.

Answer 5

Queries are statements used to manipulate data and collect data for display. They consist of the basic select to read data, delete to remove it (always use with caution), update to change it and insert to create new data, and most systems include create queries for creating tables on the run.

Answer 6

A message sent to a database to get back information.