MySQL LEFT() function

LEFT() function

MySQL LEFT() returns a specified number of characters from the left of the string. Both the number and the string are supplied as arguments of the function.

This function is useful in -

• Substring extraction: It extracts characters from the left side of a string.
• Data truncation: The LEFT() function truncates or limits the length of a string by extracting only a certain number of characters.
• Data manipulation: LEFT() is commonly used to extract part of a string or modify its content based on the leftmost characters in a string.

Syntax:

LEFT (string, length)

Arguments:

Syntax Diagram:

MySQL Version: 8.0

Pictorial Presentation:

Example of MySQL LEFT() function

The following MySQL statement returns the pub_name and 5 characters from the left of pub_name from the publisher table.

Code:

SELECT pub_name, LEFT(pub_name, 5) 
FROM publisher; 

Sample table: publisher

Output:

mysql> SELECT pub_name, LEFT(pub_name, 5) 
    -> FROM publisher;
+------------------------------+-------------------+
| pub_name                     | LEFT(pub_name, 5) |
+------------------------------+-------------------+
| Jex Max Publication          | Jex M             | 
| BPP Publication              | BPP P             | 
| New Harrold Publication      | New H             | 
| Ultra Press Inc.             | Ultra             | 
| Mountain Publication         | Mount             | 
| Summer Night Publication     | Summe             | 
| Pieterson Grp. of Publishers | Piete             | 
| Novel Publisher Ltd.         | Novel             | 
+------------------------------+-------------------+
8 rows in set (0.00 sec)

Example of MySQL LEFT() function with where clause

The following MySQL statement returns the pub_name(s) who belong to the USA and 5 characters from the left of those pub_name(s) from the publisher table.

Code:

SELECT pub_name,LEFT(pub_name,5) 
FROM publisher 
WHERE country='USA'; 

Sample table: publisher

Output:

mysql> SELECT pub_name,LEFT(pub_name,5) 
    -> FROM publisher 
    -> WHERE country='USA';
+--------------------------+------------------+
| pub_name                 | LEFT(pub_name,5) |
+--------------------------+------------------+
| Jex Max Publication      | Jex M            | 
| Mountain Publication     | Mount            | 
| Summer Night Publication | Summe            | 
+--------------------------+------------------+
3 rows in set (0.00 sec)

Video Presentation:

All String Functions (Slides presentation)

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