Sparse Lookup Query

[parag.s.27]

I searched about sparse lookup but did not find relevant information regarding my query.Hence posting it here :

I need to do a lookup of field ADDRESS_LINE_4 in one table on another field COUNTY of reference table (two diff. tables) and bring PROVINCE as a lookup result from reference table. The condition is i need to search in ADDRESS_LINE_4 (which contains entire address of a person) for a string which matches COUNTY value. For e.g. ADDRESS_LINE_4 contains value as 'DUBLIN 14' but COUNTY contains 'DUBLIN'. Note that ADDRESS_LINE_4 is coming from a dataset while COUNTY is coming from another table. I am trying to use sparse lookup for this.But since the two fields are coming from two different tables. The lookup is giving 0 output records.
How can this be performed ?

[srikanth386]

When we are having reference table contain more data than primary file, we will use sparse lookup. make sure before doing lookup trim the ADDRESS_LINE_4 field.