SQL Basic
SQL HOMESQL Intro
SQL Syntax
SQL Select
SQL Distinct
SQL Where
SQL And & Or
SQL Order By
SQL Insert
SQL Update
SQL Delete
SQL Demo
SQL Try ItSQL Advanced
SQL TopSQL Like
SQL Wildcards
SQL In
SQL Between
SQL Alias
SQL Joins
SQL Inner Join
SQL Left Join
SQL Right Join
SQL Full Join
SQL Union
SQL Select Into
SQL Create DB
SQL Create Table
SQL Constraints
SQL Not Null
SQL Unique
SQL Primary Key
SQL Foreign Key
SQL Check
SQL Default
SQL Create Index
SQL Drop
SQL Alter
SQL Increment
SQL Views
SQL Dates
SQL Nulls
SQL isnull()
SQL Data Types
SQL Functions
SQL FunctionsSQL avg()
SQL count()
SQL first()
SQL last()
SQL max()
SQL min()
SQL sum()
SQL Group By
SQL Having
SQL ucase()
SQL lcase()
SQL mid()
SQL len()
SQL round()
SQL now()
SQL format()
SQL Quick Ref
SQL Hosting
SQL Summary
SQL Quiz
SQL QuizSQL Functions
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SQL has many built-in functions for performing calculations on data.
SQL Aggregate Functions
SQL aggregate functions return a single value, calculated from values in a column.
Useful aggregate functions:
- AVG() - Returns the average value
- COUNT() - Returns the number of rows
- FIRST() - Returns the first value
- LAST() - Returns the last value
- MAX() - Returns the largest value
- MIN() - Returns the smallest value
- SUM() - Returns the sum
SQL Scalar functions
SQL scalar functions return a single value, based on the input value.
Useful scalar functions:
- UCASE() - Converts a field to upper case
- LCASE() - Converts a field to lower case
- MID() - Extract characters from a text field
- LEN() - Returns the length of a text field
- ROUND() - Rounds a numeric field to the number of decimals specified
- NOW() - Returns the current system date and time
- FORMAT() - Formats how a field is to be displayed
Tip: The aggregate functions and the scalar functions will be explained in details in the next chapters.
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