Question

What is a relational database query? explain with an example?

Answer 1

Answer:

A computer database includes tables containing rows and columns. as an example, a typical business order entry information would come with a table that describes a client with columns for name, address, sign so forth.

Explanation:

Another table would describe associate degree order, as well as data just like the product, customer, date and sales worth.

A user will get a information report showing the info they have. as an example, a branch workplace manager may need a report on all customers that bought product when a precise date. A money services manager within the same company may, from an equivalent tables, get a report on accounts that require to be paid.

When making a computer database, users outline the domain of potential prices during a knowledge column and constraints which will apply thereto knowledge value. as an example, a site of potential clients may enable up to ten potential customer names, however it's restricted in one table to permitting solely 3 of those client names to be identifiable.

#SPJ2

Answer 2

Relational database:

• A relational database is made up of rows and columns of tables.
• A table listing a customer's name, address, phone number, and other details might be present in a typical business order entry database.

For example:

• Here is a simple example of two tables that a small business might use to handle product orders.
• The first table is a customer information table and each record includes the customer's name, address, phone number, shipping address, and billing address.
• Each piece of information (each attribute) is contained in a separate column, and the database assigns a unique ID to each row (a key).
• Each entry in the second table, which is a customer order table, includes the customer ID, the product ordered, the quantity, the preferred size and color, and so on—but not the customer's name or contact information.
• The sole resemblance between these two tables is the ID column (the key).
• However, because of that shared column, the relational database can create a relationship between the two tables.
• When the company's order processing application submits an order to the database, it can then access the customer order table, retrieve the pertinent information about the product order, and use the customer ID from that table to look up the customer's billing and shipping information in the customer info table.
• The proper item may then be taken out of the storage facility, the customer's order can be delivered on time, and the company can receive paid.

Structured relational database:

• The relational paradigm distinguishes between the logical data structures—the data tables, views, and indexes—and the physical storage structures.
• Database administrators can adjust the physical storage of data without affecting how that data is accessible logically as a result of this separation.
• For instance, changing the name of a database file has no impact on the tables that are kept within.
• The logical and physical categories include database operations, which are explicitly defined operations that let programs change the contents and structures of the database.
• Logical operations allow an application to identify the resources it requires, whereas physical operations determine how to acquire the data and then do the task.
• To ensure that data is continually correct and readily available, relational databases follow specific integrity criteria.
• An integrity rule could specify that duplicate rows are not allowed in a table to stop erroneous data from being entered into the database.

#SPJ2