As far as the management of a database is concerned, SQL has quite a number of tools for the handling, processing and manipulation of data. Among these tools, functions and procedures that are stored make it easier to structure and execute complex interactions with the database. These two concepts – stored procedures and functions – are sometimes used to suggest the same thing, however, they are quite diverse. So that you can optimize the use of such capabilities in your work with SQL, first you need to learn the difference between them.
The term stored procedure is known as a collection of SQL commands that is kept and run on the database server. Their scope encompasses anything from simple data changes to more complex business logic, challenging calculations and even the issuance of commands. A function, on the other hand, is conceptually identical to a stored procedure, but is aimed at returning a value obtained from executing a query or some other calculations. From the point of going through the difference, the basic distinction one can put between a stored procedure and a function is a fact that functions return something while stored procedures only provide the functionality of doing something without making it mandatory to return something.
This article aims at addressing both the stored procedures and the functions in SQL. Their explanations will be followed by how they are made, how they differ whichever cases, and their importance in database management.
What is a Stored Procedure?
A stored procedure is a compilation of commands in SQL syntax saved within a database and authorized to be executed using a single call. Such procedures are useful in eliminating and streamlining repetitive tasks, automation of business processes, and ensuring operations are standard. After creating a stored procedure, there is no need to type in SQL code all over again; you only have to call the procedure once.
One major benefit of stored procedures is that they reduce the amount of traffic over the network. When an application client has to execute more than one SQL operation, one better way than sending multiple SQL commands to the server individually is to call the stored procedure on the client which will carry out the relevant functions on the server. This makes for speedier activity and reduced network traffic.
What is a Function?
In SQL, a function can be understood as a phrase that is used for returning a value and is a type of stored program. A function can receive input values, compute them, and utilize the processed forms for return values. Compared to this, in the case of a SQL stored procedure, it does not always return a value because its primary purpose is to execute SQL statements, while in the case of a function, it returns the value of an integer type. In SQL syntax, the ability to calculate or turn data is quite essential within query context.
Functions are often used as a tool in SQL syntax for in-built purposes such as calculations but also creates new defined functions that return values when called by users. Functions can also be used in a SELECT statement or in appendage with other queries in SQL making them handy and useful for selection or filtering of data.
Creating Stored Procedures and Functions
Functions and stored functions are created using the CREATE FUNCTION command in SQL. In the SQL language, this command also exists for invoking stored functions as well as creating them, and the command is called CREATE FUNCTION.
Users can create a procedure for repeating tasks such as inserting, updating, or deleting data in a table. Also, when creating a function it may require specification of the operations required to produce a result, for instance calculating a total or computing the average of a logical set of values.
The syntax for creating stored procedures and functions varies in slight respects in different database systems, but basically, the same idea prevails. Both stored procedures and functions contain SQL code that can be called and executed several times with the specified parameters.
Key Differences Between Stored Procedures and Functions
Regarding SQL logic that is to be encapsulated, both stored procedures and functions permit that, but there are some notable areas of divergence: 
1. Return Values:
The most significant difference between a stored procedure and functions is that a procedure will not guarantee to return any value while a function will always return a value. This means that a function is guaranteed to return one and only one value or a table, depending on the context within which such function is invoked. Conversely, a paging system is needed for a stored procedure as one is usually used to perform one or more of such actions: changing content or the order in which specific tasks are completed.
2. Uses In SQL Statements:
Speaking to functions, these can also be utilized inside SQL queries which means you can use a function from a SELECT statement, from a WHERE clause, or from an ORDER BY clause. On the other hand, stored procedures are not commonly applied in the case of SQL queries. Rather, they are called on their own when there is a need to fulfill a logic.
3. Side Effects:
A side effect such as updating or deleting useful data in a table can be done by a stored procedure while a function which is mostly benign does not have such. In such cases, such as where you only need to return a value without having to change the state of any database, the function will likely work better because there is less to worry about.
4. Transaction Control:
As regards their characteristic features, procedures are able to control transactions such as origin and commitment of transactions while functions are typically considered as not authorized to perform direct manipulation of a transaction. This enables the stored procedures to be more adaptable to practices that need amendments to the database including conditions that allow for rollback.
Why the Need to Use Stored Procedures and Functions?
Stored procedures and functions as well have their advantages in relation to operations with the database and its services to the clients as well as its performance and maintenance. - Reusability:
In data management, there is a concept of reusability where that specific piece of SQL logic which can be incorporated using a single code which can be later on used multiple times in future thus making it easier to alter all the SQL scripts in existence.
- Security:
In order to protect the data present in the tables, users are advised to limit the tables and grant the necessary permissions through stored procedures which would help users to gain accessing the required tables while following the set rules limiting the access to the rest.
- Performance:
Performance problems are common in databases that have to deal with large number of records, however with the set of stored procedures and functions to be set in place it can reduce the frequency of such occurrences and improve the way the database has to retrieve either multiple SQL functions or simply one.
- Consistency:
In a huge multi-user environment consistency becomes a problem as then the data may lead to having different values due to the lacking of uniformity, hence a stored procedure comes in hand as it helps alter the data throughout all applications at once making the task at hand easy speed wise.
- Code Organization:
You can deal with complexity in your SQL code by isolating it in stored procedures or functions in the way that allows you to structure your code better. This makes SQL queries more straightforward and readable, and easier to manage and take care of in the future.
