Dynamic Parameter Specification 
A dynamic parameter specification is used in JDBC in the statement text of a java.sql.PreparedStatement as parameter marker.
Syntax
<dynamic parameter specification> ::= '?'
Open SQL allows the use of the <dynamic parameter specification>:
as the right side of a comparison,
as the <update source> that is contained in an <update statement>,
as a value in the VALUES clause of an <insert statement>,
as an <in value> in an <in predicate>,
More information: In predicate
as lower or upper test value in a <between predicate>,
as <pattern> or <escape character> of a <like predicate>.