SQL Functions

SQL provides many built-in functions to perform operations on data. These functions are useful while performing mathematical calculations, string concatenations, sub-strings etc. SQL functions are divided into two catagories,

  • Aggregrate Functions
  • Scalar Functions

SQL Aggregate Functions

These functions return a single value after calculating from a group of values.

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

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