This example shows how to create a method, and then an alias for that method, to act like the Sybase-style SUBSTRING built-in function. (Note that you can also perform methods of java.lang.String on any string within SQL-J; simply select STRINGVALUE.substring(). This example just shows what to do in order to keep using your favorite syntax).
Make a class with a static method returning the requested substring to perform the function.
public class MyBuiltIns
public static String substring(java.lang.String theString,
int start, int length)
if (theString.length() > start+length-1)
return theString.substring(start-1, theString.length());
Compile the file and make sure that the class is in the CLASSPATH environment variable. Add the method as an alias.
CREATE METHOD ALIAS substr FOR MyBuiltIns.substring
Enter SQL like:
SELECT substr(name, 1, 5) FROM customers
This is the same as:
SELECT name.substring(0,4) FROM customers