Objectives
After completing this lesson, you should be able to do the following:
•Describe various types of functions available in SQL
•Use character, number, and date functions in SELECT statements
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Functions make the basic query block more powerful, and they are us d to manipulate data values. This is the first of two lessons that explore functions. It focuses on single-row character, number, and date functions.
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Oracle Database 11g: SQL Fundamentals I 3 - 2
Lesson Agenda
•Single-row SQL functions
•Character functions
•Number functions
•Working with dates
•Date functions
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Oracle Database 11g: SQL Fundamentals I 3 - 3
SQL Functions
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Function
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Function performs |
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arg 2 |
Result |
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Copyright © 2009, Oracle. All rights reserved. |
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• Format dates and numbers for display |
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Functions are a very powerful feature of SQL. They can be used to do the following: |
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• Perform calculations on data |
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• Modify individual data items |
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• Manipulate output for groups of rows |
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• Convert column data types |
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SQL functions sometimes take arguments and always return a value. |
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(11.1). |
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Note: If you want to know whether a function is a SQL:2003 compliant function, refer to the Oracle Compliance To Core SQL:2003 section in Oracle Database SQL Language Reference 11g, Release 1
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Oracle Database 11g: SQL Fundamentals I 3 - 4
Two Types of SQL Functions
Functions
Single-row
functions
Multiple-row
functions
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Return one result |
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Two Types of SQL Functions |
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Copyright © 2009, Oracle. All rights reserved. |
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There are two types of functions:
•Single-row functions
•Multiple-row functions
Single-Row Functions |
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These functions operate on single rows only and return o e resu t per row. There are different types |
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of single-row functions. This lesson covers the followingOnlyo es: |
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• Character |
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• Number |
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• Date |
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• Conversion |
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Multiple-Row Functions |
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Functions an manipulate groups of rows to give one result per group of rows. These functions are also known as group functions (covered in lesson 5 titled “Reporting Aggregated Data Using the Group Functions”).
Note: For more information and a complete list of available functions and their syntax, see the topic,
Functions in Oracle Database SQL Language Reference 11g, Release 1 (11.1).
Oracle Database 11g: SQL Fundamentals I 3 - 5