SUBSTRING(str,pos)

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. The forms that use FROM are standard SQL syntax. 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.

SELECT SUBSTRING('Quadratically',5);
'ratically'
SELECT SUBSTRING('foobarbar' FROM 4);
'barbar'
SELECT SUBSTRING('Quadratically',5,6);
'ratica'
SELECT SUBSTRING('Sakila', -3);
'ila'
SELECT SUBSTRING('Sakila', -5, 3);
'aki'
SELECT SUBSTRING('Sakila' FROM -4 FOR 2);
'ki'