InStr () substr () ____oracle in Oracle

InStr (String,substring[,start[,occurence]])
Third parameter, start the search location
The fourth argument, the substring of the search appears several times.

such as: Select InStr (URL, ' X ', 1,2), URL from table_name where select_condition

Result: Returns the string "X" to appear in the URL for the second time: 11
Note: 1.url= "ABC_DBDJX_XLJXJL_ABCD"

2.table_name and Select_condition are replaced with actual table names and query conditions, respectively.

SUBSTR (string, start position, end position)