Java Programming with Oracle JDBC

Chapter 15. Weakly Typed Object SQL

Weakly typed object SQL refers to the use of structures, arrays, and references to insert, update, delete, and select SQL objects. A structure refers to a structured SQL data type, which is a user-defined SQL data type synonymous with a Java class. An array refers to a SQL ARRAY, and a reference refers to a SQL REF. These SQL data types are represented in JDBC by the java.sql.Struct, java.sql.Array, and java.sql.Ref interfaces. A Struct is a JDBC object that retrieves a database object. It represents the locator for a structured SQL data type, or database object, in your Java program. After retrieving a database object with a Struct, you retrieve the object’s attributes by calling its getAttributes( ) method, which returns a Java Object array. Since the attributes are returned as an Object array, it’s up to you, the programmer, to properly cast each object value as it is used. Hence, a Struct is weakly typed. If, in turn, an attribute of the Struct represents another structured SQL data type, or database object, then that attribute must itself be cast to the Struct. Likewise, if the attribute of a Struct is an array of values, such as an Oracle varying array or nested table, then you must cast that attribute to another JDBC object type, an Array.

Similar to a Struct, an Array represents the locator for a SQL ARRAY. It has a method, getArray( ), which returns the database array values as a Java Object array. If an element of the returned Object ...