String Functions

3.3

String Functions

CONCAT

Combines a list of strings into a single string.
Can include column values and literal values.
In MySQL literal values can be enclosed with either single ( ‘ ) or double quotes ( “ ) .

Example:

USE world; SELECT CONCAT(name, ', ', continent) FROM country;

Results:

RIGHT, LEFT

The RIGHT and LEFT functions have two parameters. The first is a string and the second is the number of characters to be returned.
The RIGHT function starts counting from the right side of the string. • The LEFT function starts counting from the left side of the string.

Table 7. RIGHT, LEFT functions

Function	Type	Example	Result
RIGHT(string, num. characters)	string	RIGHT(‘Salmon’, 3)	mon
LEFT(string, num. characters)	string	LEFT(‘Salmon’, 3)	Sal

Example:

USE bike; SELECT category_name, LEFT(category_name, 8) AS 'First 8 Characters', RIGHT(category_name, 8) AS 'Last 8 Characters' FROM category;

Results:

TRIM, LTRIM, RTRIM

The TRIM function will remove leading and trailing spaces from a string.
The LTRIM function will remove leading spaces from a string.
The RTRIM function will remove trailing spaces from a string.

Table 8. TRIM functions

Function	Type	Example	Result
TRIM(string)	string	TRIM(‘ Salmon ‘)	‘salmon’
LTRIM(string)	string	LEFT(‘Salmon ‘)	‘salmon ’
RTRIM(string)	string	RIGHT(‘ Salmon‘)	‘ salmon’

Example:

SELECT LTRIM(' Salmon ') AS "Left Trim", RTRIM(' Salmon ') AS "Right Trim", TRIM(' Salmon ') AS "Trim";

Results:

FORMAT

FORMAT() accepts a decimal but returns a comma formatted string.

Table 9. FORMAT functions

Function	Type	Example	Result
FORMAT(number, decimal)	string	FORMAT(1234.342, 2)	-356

Code Sample:

SELECT FORMAT(list_price,2) FROM bike.product;

Results:

LOWER, UPPER

LOWER() converts all characters to lower case.
UPPER() converts all characters to upper case.

Table 9. LOWER, UPPER functions

Function	Type	Example	Result
LOWER(string)	string	LOWER(‘Salmon ‘)	‘salmon’
UPPER(string)	string	UPPER(‘Salmon‘)	‘SALMON’

Example:

SELECT UPPER('Salmon'), LOWER('Salmon');

Results:

LOCATE, LENGTH, SUBSTRING

LOCATE(), and LENGTH() accept a string but return an integer. • SUBSTRING() accepts a string and returns a string.

Table 9. LOCATE. LENGTH, SUBSTRING functions

Function	Type	Example	Result
LOCATE(find,search[,start])	string	LOCATE(‘al’,’salmon’,1)	2
LENGTH(str)	string	LENGTH(‘salmon’)	6
SUBSTRING(str,start[,length])	string	SUBSTRING('salmon',3,999)	‘lmon’

Example:

SELECT LOCATE('al','salmon',1), LENGTH('salmon'), SUBSTRING('salmon',3,999);

Results:

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