PostgreSQL LEFT() Function

The PostgreSQL LEFT() function is used to extract a substring from a string, starting from the left-most character.

Syntax

LEFT(string, n)

Parameters

`string`	`Required.` Specify the string to extract from.
`n`	`Required.` Specify the number of characters to extract. If this parameter exceeds the length of the string, this function will return string. If this parameter is negative, this function will return the string after removing the last \|n\| characters.

Return Value

Returns the substring extracted from specified string.

Example 1:

The example below shows the usage of LEFT() function.

SELECT LEFT('AlphaCodingSkills.com', 1);
Result: 'A'

SELECT LEFT('AlphaCodingSkills.com', 5);
Result: 'Alpha'

SELECT LEFT('AlphaCodingSkills.com', 21);
Result: 'AlphaCodingSkills.com'

SELECT LEFT('AlphaCodingSkills.com', 50);
Result: 'AlphaCodingSkills.com'

SELECT LEFT('Alpha Coding Skills', 5);
Result: 'Alpha'

SELECT LEFT('AlphaCodingSkills.com', -4);
Result: 'AlphaCodingSkills'

Example 2:

Consider a database table called Employee with the following records:

PhoneNumber	EmpID	Address
+33-147996101	1	Grenelle, Paris, France
+31-201150319	2	Geuzenveld, Amsterdam, Netherlands
+86-1099732458	3	Yizhuangzhen, Beijing, China
+65-67234824	4	Yishun, Singapore
+81-357799072	5	Koto City, Tokyo, Japan

In the query below, the LEFT() function is used to extract the country code from the PhoneNumber column records.

SELECT *, LEFT(PhoneNumber, 3) AS CountryCode 
FROM Employee;

This will produce the result as shown below:

PhoneNumber	EmpID	Address	CountryCode
+33-147996101	1	Grenelle, Paris, France	+33
+31-201150319	2	Geuzenveld, Amsterdam, Netherlands	+31
+86-1099732458	3	Yizhuangzhen, Beijing, China	+86
+65-67234824	4	Yishun, Singapore	+65
+81-357799072	5	Koto City, Tokyo, Japan	+81

❮ PostgreSQL Functions