PostgreSQL LEFT() function
LEFT() function
The PostgreSQL left() function is used to extract n number of characters specified in the argument from the left of a given string. When the value of n is negative, the extraction will happen from left except last n characters.
Syntax:
left(string,n)
PostgreSQL Version: 9.3
Pictorial Presentation of PostgreSQL LEFT() function
Example: PostgreSQL LEFT() function:
In the example below, the left function extracted 3 characters from the left of the string 'w3resource'.
Code:
SELECT left('w3resource',3)
AS "Extract 3 characters from the left";
Sample Output:
Extract 3 characters from the left ------------------------------------ w3r (1 row)
Example: PostgreSQL LEFT() function using negative value:
In the example below, the left function extracted all the characters from the left side except 3 rightmost characters from the string 'w3resource', because the value of extracting character number is negative.
Code:
SELECT left('w3resource',-3)
AS "Extract all characters except 3 rightmost";
Sample Output:
Extract all characters except 3 rightmost ------------------------------------------- w3resou (1 row)
Example: PostgreSQL LEFT() function using columns of table:
Sample Table: employees
If we want to display the first_name, last_name for those employees whose first 3 characters of their name contain 'Nan' from employees table, the following sql statement can be used:
Code:
SELECT first_name, last_name
FROM employees
WHERE left(first_name,3)='Nan';
Sample Output:
first_name | last_name ------------+----------- Nancy | Greenberg Nanette | Cambrault Nandita | Sarchand (3 rows)
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