How to Use the LEFT() Function in MySQL
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Contents
In this article, you will learn how to use the LEFT() function in MySQL.
Using the LEFT() function in MySQL
In MySQL, the LEFT() function is used to extract a specified number of characters from the beginning of a string.
Syntax
LEFT(str, length);
Examples
Here are some examples of using the LEFT() function in MySQL:
Extracting the first N characters of a string
To extract the first N characters of a string, you can use the LEFT() function.
Syntax
SELECT LEFT(str, length);
Example
SELECT LEFT('Hello World', 5);
Output:
+------------------------+
| LEFT('Hello World', 5) |
+------------------------+
| Hello |
+------------------------+
In this example, the LEFT() function returns the first 5 characters of the string ‘Hello World’, which are ‘Hello’.
Extracting the first N characters of a column value
You can also use the LEFT() function to extract the first N characters of a column value.
Syntax
SELECT LEFT(column_name, length) FROM table_name;
Example
SELECT LEFT(name, 3) FROM employees;
Output:
+--------------+
| LEFT(name, 3) |
+--------------+
| Joh |
| Ann |
| Mic |
| Sara |
+--------------+
In this example, the LEFT() function returns the first 3 characters of the name column in the employees table.
Using the first N characters of a string in a WHERE clause
You can use the LEFT() function in a WHERE clause to filter records based on the first N characters of a string.
Syntax
SELECT * FROM table_name WHERE LEFT(column_name, length) = string_value;
Example
SELECT * FROM employees WHERE LEFT(name, 3) = 'Joh';
Output:
+----+------+--------+--------+
| id | name | salary | hire_date |
+----+------+--------+--------+
| 1 | John | 50000 | 2020-01-01 |
+----+------+--------+--------+
In this example, the SELECT statement returns all the records from the employees table where the first 3 characters of the name column are equal to ‘Joh’.