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Introduction to Procedure in SQL

Procedures or Stored Procedures in SQL are logical units of SQL queries that can be created once, fetched, and executed multiple times whenever there is a need to repeat the same operation. It also allows passing parameters, like the stored procedure with arguments in the OOPS concept. It is categorized under DML (Data Manipulation Language) of SQL programming, as it is applicable to operations involving data management and manipulation.

What is SQL?

Structured Query Language (SQL) is sometimes pronounced as the individual character “S-QL” or “see-Quel”. It is used to query, manipulated, or update data in the relational database. It is used to insert or update or delete records in a database. One of the main functionality of SQL is maintaining a database.

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Syntax of SQL query to fetch all the records is as follows:

select * from table_name

Stored procedures in SQL

What is a Stored Procedure? A Stored Procedure is a collection of Structured Query Language (SQL) statements with a name assigned to them. These stored procedures are stored in a relational database management system (RDBMS). So it is possible for multiple calling of the procedures to reduce multiple executions and resulting in reduced execution time. Data can be modified using procedures, and the major advantage is that it is not tied to a particular application.

Stored procedures can accept parameters as input and can return multiple values as an output parameter. In SQL Server, stored procedures perform operations in the database and can return a status value to an application or a batch calling procedure. User-defined procedures are created using the user-defined database, with the exception when we have a read-only database. For that, we need to develop it in Transact SQL (T-SQL). Tempdb is where all the temporary procedures are stored.

There are two types of stored procedures we have

  1. Local procedures
  2. Global procedures

Local procedures are the one which is only visible for the user using it in the connection, whereas Global procedures are visible to any of the users in the same connection.

Structure of creating the procedure

Here, the owner means the database name, and to pass the parameter, we need to add the ‘@’ symbol.

CREATE PROCEDURE <owner>.<procedure name>
<param> <datatype>
AS
<Body>
Execute a Stored Procedure
Exec is the command for the execution of the procedure.
EXEC Procedure_name

Comparison between Stored procedure and Functions

Stored procedures and functions can be used to achieve the same functionality. We can customize both procedures as well as functions. The difference between them is functions are designed to send their output to Transact SQL, and stored procedures are designed to return output to a query, as well as they can return output to T-SQL also. Applications can have input from the stored procedures, while user-defined functions can return table variables, and they are not privileged to change the environment settings neither operating system environment.

Database Company

Company Category Item
Tarle edibles cookies
Tarle edibles chips
Lakme cosmetics lipstick
Brisket grocery Flax seeds
Brisket edibles biscuits
Brisket grocery oil
ole cosmetics Nail polish
ole cosmetics Hairbrush

Stored Procedure Example

The following SQL statement creates a stored procedure that selects the company.

CREATE PROCEDURE SelectAllExample
AS
SELECT * FROM company GO;

Execute the stored procedure above as follows:

Executing the above-stored procedure, we can use the following command:

EXEC SelectAllExample;

Stored Procedure Example With One Parameter

The following SQL statement creates a stored procedure with a single parameter to be passed that selects a company with an item as a parameter.

CREATE PROCEDURE SelectAllExample @item nvarchar(30)
AS
SELECT * FROM company WHERE item = @item GO;

Execute the stored procedure above as follows:

To execute the above-stored procedure with one parameter, we can use the following command:

EXEC SelectAllExample item = "cookies";

Stored Procedure Example With Multiple Parameters

The following SQL statement creates a stored procedure with multiple parameters that select company with item and category as a parameter

CREATE PROCEDURE SelectAllExample @item nvarchar(30), @ category nvarchar(10)
AS SELECT * FROM company WHERE item = @ item AND category = @ category GO;

Execute the stored procedure above as follows:

To execute the above-stored procedure with multiple parameters, we can use the following command we need to pass the multiple parameters with comma-separated: EXEC SelectAllExample item =”cookies”, category =”edibles”;

Advantages and Disadvantages of Procedure in SQL

Below are the advantages and disadvantages:

Advantages

Let us see some of the advantages:

  • Application improvement can be achieved by procedures. If a procedure is called multiple times in a single application, then the compiled version of the procedure is utilized.
  • Traffic between the database and the application can be reduced as the big statements are already fed into the database, and we don’t have to send it again and again.
  • Using procedures, code reusability can be achieved, similar to the functions and methods that work in the java and other programming languages.

Disadvantages

Below are the disadvantages:

  • Stored Procedures consume a lot of memory. It is the duty of a database administrator has to decide an upper bound to how many stored procedures are feasible for a particular application.
  • Stored procedures cannot be debugged using MySQL.

Conclusion – What is Procedure in SQL

  • Simple non-select statements, including DML, statements like Insert and delete, also DDL statements such as Drop and Create can be included in the stored programs.
  • Memory consumption is more, but the seek rate can be reduced, and code reusability is beneficial.
  • Stored procedures can be implemented with or without variables and can be executed by passing the parameters if required.

Recommended Articles

This has been a guide to What is Procedure in SQL. Here we have discussed the structure, examples, advantages, and disadvantages of the procedure in SQL. You may also have a look at the following articles to learn more –

  1. What is SQL Server?
  2. What is MySQL Database
  3. MySQL OpenSource
  4. What is SQL
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