Suppose this query against an OData4-backed view:

SELECT STRINGKEY FROM BQT1.SmallA WHERE LOCATE('1', stringkey) = 1

The WHERE clause gets translated into

filter=indexof('1',stringkey) eq 1

There are two issues with this:

• the arguments of the indexof function should be in the opposite order (the sought-after string goes second)
• indexof function indexes characters in strings from 0 whereas LOCATE from 1, this needs to be taken into account

The correct filter in this case should be:

filter=indexof(stringkey,'1') eq 0

See http://docs.oasis-open.org/odata/odata/v4.0/odata-v4.0-part2-url-conventions.html#startswithurl5.1.2.4.3