UDSF in Lua: Example 2

This example creates a function called unique_chars that counts the number of unique characters in a string and returns the result.

Code

Put the following code into the file /tmp/udsf_example2.nzl:

-- count the number of distinct letters in a string
-- USAGE: unique_chars('abc123zzzz')

function unique_chars( str )
      count = 0
      chars = {}

      for ch in string.gmatch(str, "." ) do
        if chars[ch] == null then
          chars[ch] = 1
          count = count + 1
        end
      end

      return count
end

function getType()
      return udf
end

function getName()
      return "unique_chars"
end

function
      getArgs()
      return {{ "", varchar(any) }}
end

function getResult()
      return "integer"
end

function getComment()
      return "A Sizer Example using UDSF"
end

Compression

Compress the file /tmp/udsf_example2.nzl into a file with the name /tmp/udsf_example2.tar.

Deployment

Deploy the UDX to a Db2® instance by issuing the following CLPPlus command:

SQL> IDA DEPLOYUDX SRC /tmp/udsf_example2.tar LANGUAGE lua PROJECT example2

Running

Use this function in a query, for example:

values unique_chars('abc123zzzz')

This returns the following result:

1
-----------
          7