## Introduction

Oracle has a lot of powerful functions.

SQL functions have a name, followed by one or more arguments (between parentheses) in a comma-separated list.

You can use functions in expressions, in the same way that you can use operators.

These are the six SQL function categories, based on their operand types:

- Numeric functions
- Alphanumeric functions
- Group functions
- Date functions
- Conversion functions
- Other functions

T?he following table lists some examples of SQL functions.

Function | Explanation |
---|

AVG(MSAL) | The average monthly salary |

SQRT(16) | The square root of 16 |

LENGTH(INIT) | The number of characters in the INIT column value |

LOWER(ENAME) | ENAME column value, in lowercase |

SUBSTR(ENDDATE,4,3) | Three characters of the ENDDATE column value, from the fourth position |

Oracle allows you to create your own SQL functions by using the PL/SQL or Java languages.