substring

Returns a substring of str starting at position pos.

substring(str, pos [, len])

If pos is negative, the returned string will start pos characters from the end of str.

If len is omitted, the result is the substring from position pos until the end of str.

If len is provided, the substring of str len characters long starting at position pos is returned. In case that len is smaller than 0, the result will be an empty string.

Examples:

evql> SELECT substring("foobar", 2);
      -> "oobar"

evql> SELECT substring("foobar", -3, 2)
      -> "ba"