The BYTE_SUBSTR64 and BYTE_SUBSTR functions return the byte substring of the large object column or variable parameter.
BYTE_SUBSTR64( large-object-column, start, length )
BYTE_SUBSTR( large-object-column, start, length )
large-object-column – the name of a LONG VARCHAR or LONG BINARY column or variable.
start – an integer expression indicating the start of the substring. A positive integer starts from the beginning of the string, with the first byte at position 1. A negative integer specifies a substring starting from the end of the string, with the final byte at position -1.
length – an integer expression indicating the length of the substring. A positive length specifies the number of bytes to return, starting at the start position. A negative length specifies the number of bytes to return, ending at the start position.