SQL Common functions

The database has a number of built-in functional performance calculation data.

SQL for aggregate functions
The total SQL function returns a single value calculation, from the value of a column.

Standard features of SQL
The SQL scalar function returns a single value based on the input value.

Useful standard function:

UCASE ()-Uppercase of the conversion realm
LCASE ()-Convert one field to lowercase
Min ()-Extract the text field of the character
Len ()-The length text field returned
ROUND ()-Rounds a number of specific decimal places in a digital field
Now ()-Returns the current system date and time
Format ()-How formatting is displayed in the field
Tip: The total number of functions and responsibilities will be explained in detail in future chapters.

Useful aggregate functions:

AVG ()-the average value returned
Count ()-Number of rows returned
First ()-Returns the number one value
Last ()-Returns the final value
Max ()-Maximum value to return
MIN ()-Returns the smallest value
Total ()-The sum returned

The above SQL functions are commonly used by us, especially to the novice has a lot of help Oh,