specifies a string
to search; this can be specified as string constant, field name, or
expression.
excerpt
specifies a string
to search for within source;
this can be specified as string constant, field name, or expression.
Optional Argument
count
specifies an integer
that indicates the occurrence of excerpt to
search for; this can be specified as numeric constant, field name,
or expression. For example, a value of 2 indicates to search for the
second occurrence of excerpt in source.
Details
The INSTR function searches source from
left to right for the count-th
occurrence of excerpt. If excerpt is
not found in source, the function
returns a value of 0.
Example
source = "This is a simple sentence."
excerpt = "is"
position = instr(source, excerpt, 1) // outputs 3
position = instr(source, excerpt, 2) // outputs 6