SUBSTRING

SUBSTRING function is used to extract a string containing a specific number of characters from a particular position of a given string. The forms without a len argument return a substring from string str starting at position pos. The forms with a len argument return a substring len characters long from string str, starting at position pos. It is also possible to use a negative value for pos. In this case, the beginning of the substring is pos characters from the end of the string, rather than the beginning. A negative value may be used for pos in any of the forms of this function. A value of 0 for pos returns an empty string. The position of the first character in the string from which the substring is to be extracted is reckoned as 1.

Syntax

SUBSTRING(str,pos);
SUBSTRING(str FROM pos);
SUBSTRING(str,pos,len);
SUBSTRING(str FROM pos FOR len)

Arguments

Arguments	Description
str	The main string from where the character to be extracted
pos	The one-indexed position expression to start at. If negative, counts from the end
len	The number expression of characters to extract

Return Type

A string data type value.

Examples

SELECT SUBSTRING('Quadratically',5)
+-------------------------------+
| substring('Quadratically', 5) |
+-------------------------------+
| ratically                     |
+-------------------------------+

SELECT SUBSTRING('foobarbar' FROM 4);
+---------------------------+
| substring('foobarbar', 4) |
+---------------------------+
| barbar                    |
+---------------------------+

SELECT SUBSTRING('Quadratically',5,6);
+----------------------------------+
| substring('Quadratically', 5, 6) |
+----------------------------------+
| ratica                           |
+----------------------------------+

SELECT SUBSTRING('Sakila', -3);
+----------------------------+
| substring('Sakila', (- 3)) |
+----------------------------+
| ila                        |
+----------------------------+

SELECT SUBSTRING('Sakila', -5, 3);
+-------------------------------+
| substring('Sakila', (- 5), 3) |
+-------------------------------+
| aki                           |
+-------------------------------+

SELECT SUBSTRING('Sakila' FROM -4 FOR 2);
+-------------------------------+
| substring('Sakila', (- 4), 2) |
+-------------------------------+
| ki                            |
+-------------------------------+