SQL Functions
What is a function?
A function is a predefined formula which takes one or more arguments as input then process the arguments and returns an output.
SQL function
There are two types of SQL functions, aggregate functions, and scalar(non-aggregate) functions. Aggregate functions operate on many records and produce a summary, works with GROUP BY whereas non-aggregate functions operate on each record independently.
There are so many built-in functions in SQL to do various calculations on data.
Types of SQL functions
| SQL functions | Description |
|---|---|
| SQL Aggregate Function | This function can produce a single value for an entire group or table.
They operate on sets of rows and return results based on groups of rows. Some Aggregate functions are - |
| SQL Arithmetic Function | A mathematical function executes a mathematical operation usually based on input values that are provided as arguments, and return a numeric value as the result of the operation. Mathematical functions operate on numeric data such as decimal, integer, float, real, smallint, and tinyint. Some Arithmetic functions are - |
| SQL Character Function | A character or string function is a function which takes one or more characters or numbers as parameters and returns a character value. Basic string functions offer a number of capabilities and return a string value as a result set. Some Character functions are - |
Practice SQL Exercises
- SQL Exercises, Practice, Solution
- SQL Retrieve data from tables [33 Exercises]
- SQL Boolean and Relational operators [12 Exercises]
- SQL Wildcard and Special operators [22 Exercises]
- SQL Aggregate Functions [25 Exercises]
- SQL Formatting query output [10 Exercises]
- SQL Quering on Multiple Tables [8 Exercises]
- FILTERING and SORTING on HR Database [38 Exercises]
- SQL JOINS
- SQL SUBQUERIES
- SQL Union[9 Exercises]
- SQL View[16 Exercises]
- SQL User Account Management [16 Exercise]
- Movie Database
- BASIC queries on movie Database [10 Exercises]
- SUBQUERIES on movie Database [16 Exercises]
- JOINS on movie Database [24 Exercises]
- Soccer Database
- Introduction
- BASIC queries on soccer Database [29 Exercises]
- SUBQUERIES on soccer Database [33 Exercises]
- Hospital Database
- Employee Database
- More to come!
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SQL: Tips of the Day
SQL Server SELECT into existing table.
INSERT INTO dbo.TABLETWO SELECT col1, col2 FROM dbo.TABLEONE WHERE col3 LIKE @search_key
This assumes there's only two columns in dbo.TABLETWO - you need to specify the columns otherwise:
INSERT INTO dbo.TABLETWO (col1, col2) SELECT col1, col2 FROM dbo.TABLEONE WHERE col3 LIKE @search_key
Database: SQL Server
Ref: https://bit.ly/3y6tpA3
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