BigQuery supports the STRPOS() function with accepts 2 character strings as arguments. The function returns the 1-based position of the first occurrence of the second string within the first (example below). If no occurrence is found, the function returns 0. The function also supports binary strings with the same behavior. Note that STRPOS differs from the standard POSITION function in that it counts the position of the character in a binary string, not the position of a byte.
EXAMPLE: STRPOS("abc", "bc") would return: 2.
EXAMPLE: STRPOS("abc", "d") would return: 0.