Functions are a very powerful feature of SQL and can be used to do the following:
- Perform calculations on data
- Modify individual data items
- Manipulate output for groups of rows
- Format dates and numbers for display
- Convert column data types
–SQL functions sometimes take arguments and always return a value.
Types of SQL function for performing calculations on data are:
- Arithmetic Functions
- Aggregate Functions
- Scalar Functions
SQL functions help to aggregate the data while extracting the data from Data base. There are many functions available in SQL to aggregate the data to analyse it.
Arithmetic Functions are used to perform calculations in SQL, the valid symbols are +-*/() .
SELECT EID, (SALARY/12) GROSS_SALARY FROM EMPLOYEE WHERE Department= ‘HR’ ;
SQL scalar functions return a single value, based on the input value. Various Scalar functions include: CHAR, DATE, DAY(S), DECIMAL, DIGITS, FLOAT, HEX, HOUR, INTEGER, LENGTH, MICROSECOND, MINUTE, MONTH, SECOND, SUBSTR, TIME.
SELECT Name, SUBSTRING(Name, 1, 1) AS Initial FROM Employee;
SQL aggregate functions return a single value, calculated from values in a column. Various aggregate functions are:AVG,COUNT,MAX,MIN,SUM.
SELECT AVG(SALARY) AVG-SAL FROM Employee WHERE Department= ‘Research’;
Frequently Used Functions
SQL has many built-in functions for performing processing on string or numeric data. Following is the list of all useful SQL built-in functions:
- COUNT Function – The SQL COUNT aggregate function is used to count the number of rows in a database table.
- MAX Function – The SQL MAX aggregate function allows us to select the highest (maximum) value for a certain column.
- MIN Function – The SQL MIN aggregate function allows us to select the lowest (minimum) value for a certain column.
- AVG Function – The SQL AVG aggregate function selects the average value for certain table column.
- SUM Function – The SQL SUM aggregate function allows selecting the total for a numeric column.
- SQRT Functions – This is used to generate a square root of a given number.
- RAND Function – This is used to generate a random number using SQL command.
- SQL CONCAT Function – This is used to concatenate any string inside any SQL command.