LEFT()¶

Function Description¶

The LEFT() function returns the leftmost length character in the str string. If the str or len parameter is NULL, the NULL value is returned.

Function Syntax¶

> LEFT(str,len)

Parameter definition¶

Parameters	Description
str	Required parameters. The string to extract the substring.
len	Required parameters. is a positive integer that specifies the number of characters to be returned from the left. If len is 0 or negative, the LEFT function returns an empty string. If len is greater than the length of the str string, the LEFT function returns the entire str string.

Example¶

mysql> select left('abcde', 3) from dual;
+---------------------+
| left(abcde, 3) |
+---------------------+
| abc |
+---------------------+
1 row in set (0.00 sec)

drop table if exists t1;
CREATE TABLE t1 (str VARCHAR(100) NOT NULL, len INT);
insert into t1 values('abcdefghijklmn',3);
insert into t1 values(' ABCDEFGH123456', 3);
insert into t1 values('ABCDEF GHIJKLMN', 20);
insert into t1 values('ABCDEFGHijklmn ', -1);
insert into t1 values('ABCDEFGH123456', -35627164);
insert into t1 values('', 3);
mysql> select left(str, len) from t1;
+------------------------+
| left(str, len) |
+------------------------+
| abc |
| A |
| ABCDEF GHIJKLMN |
| |
| |
| |
+------------------------+
6 rows in set (0.01 sec)

mysql> select left('sdfsdfsdfsdf', len) from t1;
+------------------------------+
| left(sdfsdfsdfsdf, len) |
+------------------------------+
| sdf |
| sdf |
| sdfsdfsdfsdfsdf |
| |
| |
| sdf |
+------------------------------+
6 rows in set (0.01 sec)