substring-before
Returns the substring of the first argument string that precedes the first occurrence of the second argument string in the first argument string.
string substring-before
(
source_strg string,
sub_strg string);
Description
If the source_strg does not contain sub_strg,
the function returns the empty string.
Otherwise, it finds the first occurrence of sub_strg and returns
the pert of source_strg that precedes the occurrence.
If any argument is not a string, it is converted to string using rules for string() XPATH function.
Parameters
source_strg –
String where the search is performed
sub_strg –
String to search
Examples
Extract year ("1999" substring) from ISO date string
substring-before('1999-12-31','-')