SQL: What are Functions?
a thread...
(Part: 1)
a thread...
(Part: 1)
1. Definition:
Functions optionally take arguments, performs some calculations or operations and returns the computed value.
Functions always return some value.
Functions optionally take arguments, performs some calculations or operations and returns the computed value.
Functions always return some value.
2. Types of Functions
Mainly there are two categories of functions:
- In-built/System Functions
- User Defined Functions
Mainly there are two categories of functions:
- In-built/System Functions
- User Defined Functions
3. In-built Functions
Several types of built-in functions exist in DB like Aggregate functions, Date functions, String functions, etc.
Let's see some built-in functions
Several types of built-in functions exist in DB like Aggregate functions, Date functions, String functions, etc.
Let's see some built-in functions
3.a. Aggregate Functions
Aggregate Functions work on the collection of data and return a single scalar value in return.
Eg:
MAX(<column>) - takes all column values and returns the maximum value.
SUM(<column>) - takes all column values and returns the sum of them.
Aggregate Functions work on the collection of data and return a single scalar value in return.
Eg:
MAX(<column>) - takes all column values and returns the maximum value.
SUM(<column>) - takes all column values and returns the sum of them.
3.b. String Functions
They take input as String, perform some operations and return back the modified String.
Eg:
UPPER(<str>): Takes the string as an argument, and returns the upper case string.
REVERSE(<str>): Returns the reversed string
They take input as String, perform some operations and return back the modified String.
Eg:
UPPER(<str>): Takes the string as an argument, and returns the upper case string.
REVERSE(<str>): Returns the reversed string
Similarly, there are tones of other in-built functions that can be found in DB.
Depending on the database you're using, their names might differ.
Above in-built functions are based on MySQL DB.
Depending on the database you're using, their names might differ.
Above in-built functions are based on MySQL DB.
4. User-Defined Functions
Sometimes, when in-built functions are not enough then we need to create our own customized functions.
Such types of functions are called User-Defined Functions.
We will see them in more detail in part 2 of this thread.
Sometimes, when in-built functions are not enough then we need to create our own customized functions.
Such types of functions are called User-Defined Functions.
We will see them in more detail in part 2 of this thread.
That's it for now!
If you liked this then you might also like my previous series on Store Procedures:
If you liked this then you might also like my previous series on Store Procedures:
Namaste, I'm Vikas!
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Every Mon, Wed & Fri - I write a thread
on Fullstack Development.
Follow @vikasrajputin to read all my future threads.
Here's the Part 2:
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