SQL Server: Reading notes from the book of "The Must-Know" (eight)

Lesson 8th using functions to process data

8.1 Functions

"Noun" portable: The code you write can run on multiple systems

8.2 Using Functions

8.2.1 Text Processing functions

Example 1: Using the UPPER () function--Convert text to uppercase

SELECT UPPER  as Vend_name_upcase  from Vendors ORDER  by Vend_name;

Commonly used text-processing functions:

• Left (): Returns the character to the ieft of the string
• DATALENGTH (): Returns the length of a string
• LOWER (): Converts a string to lowercase
• LTRIM (): Remove the space to the left of the string
• RTRIM (): Remove the space to the right of the string
• UPPER (): Converts a string to uppercase

8.2.2 Date and time processing functions

Example 2: Retrieving all orders for 2012 in the Orders table

SELECT Order_num  from Orders WHERE DATEPART = '  - ' ; --     Analysis: DATEPART () returns the year only from the Order_date column. By comparing with 2012, the WHERE clause filters only orders for this year

8.2.3 Numeric processing function

Numeric processing functions work with numeric data only. These functions are generally used primarily for algebraic, triangular, or geometric operations.

8.3 Summary

Describe the use of functions

Sequel:

SQL Server: Reading notes from the book of "The Must-Know" (vii)

SQL Server: Reading notes from the book of "The Must-Know" (eight)