Lucene: Multifield searches

We can run multifield searches in Lucene using either the BooleanQuery API or using the MultiFieldQueryParser for parsing the query text. For e.g. If a index has 2 fields FirstName and LastName and if you need to search for "John" in the FirstName field and "Travis" in the LastName field one can use a Boolean Query as such:

BooleanQuery bq = new BooleanQuery();
Query qf = new TermQuery(new Lucene.Net.Index.Term("FirstName", "John"));
Query ql = new TermQuery(new Lucene.Net.Index.Term("LastName", "Travis"));
bq.Add(qf, BooleanClause.Occur.MUST);
bq.Add(ql, BooleanClause.Occur.MUST);
IndexSearcher srchr = new IndexSearcher(@"C:\indexDir");
srchr.Search(bq);

Now if we need to search a single term across either of the FirstName and LastName fields then we can use the MultiFieldQueryParser as follows:

Query query = MultiFieldQueryParser.parse("commonName",
new String[] { "FirstName", "LastName" },
new SimpleAnalyzer());
srchr.Search(query);

Now if you need to search the term that must exist in both the fields then we use the following:

 Query query = MultiFieldQueryParser.Parse("commonName",
new String[] { "FirstName", "LastName" },
new BooleanClause.Occur[] { BooleanClause.Occur.MUST,BooleanClause.Occur.MUST}
, new SimpleAnalyzer());
srchr.Search(query);

Finally if you don’t want a term to occur in one of the Fields (say FirstName) then use:

 Query query = MultiFieldQueryParser.Parse("commonName",
new String[] { "FirstName", "LastName" },
new BooleanClause.Occur[] { BooleanClause.Occur.MUST_NOT,BooleanClause.Occur.MUST},
new SimpleAnalyzer());
srchr.Search(query);  

so if you need to search a single term across multiple fields then use MultiFieldQueryParser, if you need to search different terms in different fields then use the BooleanQuery as shown first