SQL has many built-in functions for performing operations on numeric or string values. The following is the list of all useful SQL functions with examples:
- COUNT (): It is used to returns the number of rows.
- AVG (): It is used to returns the average value.
- MAX (): It is used to returns the largest value.
- MIN (): It is used to returns the smallest value.
- SUM (): It is used to returns the sum.
- LEN (): It is used to returns the length of a text field.
- UPPER (): It is used to converts a field to upper case.
- LOWER (): It is used to converts a field to lower case.
- GETDATE (): It returns the current date and time from the server's system clock.
- DATEDIFF(): It is used to compare and return the difference between date items such as days, weeks, minutes, and hours.
AVG () Function: This function returns the average value of a numeric column.
Syntax: SELECT AVG (column_name) FROM table_name
COUNT () Function: This function returns the number of rows that match a specified criteria.
Syntax:
SELECT COUNT(column_name) FROM table_name;
MAX () Function: This function returns the largest value of the selected column.
Syntax:
SELECT MAX (column_name) FROM table_name; 
MIN () Function: This function returns the smallest value of the selected column.
Syntax:
SELECT MIN (column_name) FROM table_name;
SUM () Function: This function returns the total sum of a numeric column.
Syntax:
SELECT SUM(column_name) FROM table_name;
GROUP BY : This statement is used in conjunction with the aggregate functions to group the result-set by one or more columns.
Syntax:
SELECT column_name, aggregate_function(column_name) FROM table_name WHERE column_name operator value GROUP BY column_name;
UCASE () Function: This function converts the value of a field to uppercase.
Syntax:
SELECT UPPER (column_name) FROM table_name;
LCASE() Function: This function converts the value of a field to lowercase.
Syntax:
SELECT LOWER(column_name) FROM table_name 
LEN() Function: This function returns the length of the value in a text field.
Syntax:
SELECT LEN(column_name) FROM table_name;
GETDATE() Function: This function return the current time from the server’s system time.
Syntax: select getdate(); 
DATEDIFF () Function: This function is use to compare and return the difference between date items such as days ,weeks, minutes.
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