SQL Server full text search on column with alias

Question

I am using full-text search, its working fine on a direct column of table but not on a derived/aliased column.

SELECT ExpectationId
    ,ExpectationName
    ,(
       CASE 
          WHEN ExpectationOrganization_OrganizationId IS NOT NULL
                THEN (
                       SELECT OrganizationName
                       FROM Organizations
                       WHERE OrganizationId = ExpectationOrganization_OrganizationId
                       )
          WHEN ExpectationBeneficiary_BeneficiaryId IS NOT NULL
                THEN (
                       SELECT BeneficiaryName
                       FROM Beneficiaries
                       WHERE BeneficiaryId = ExpectationBeneficiary_BeneficiaryId
                       )
          ELSE (
                    SELECT TeamName
                    FROM Teams
                    WHERE TeamId = ExpectationTeam_TeamId
                    )
          END
       ) AS ParentName
FROM Expectations
WHERE
    FREETEXT(ExpectationName, @Keyword) ---Working
    OR FREETEXT(ParentName, @Keyword) ---Not working

All these columns ExpectationName, OrganizationName, BeneficiaryName, TeamName are full-text indexed.

How can I make it work for ParentName column?

Answer 1

You need to create a VIEW based on your query first then add a Full-Text index to it which will include the ParentName column. Without the Full-Text index over a column being searched neither FREETEXT nor CONTAINS will work.

Something like that should help you:

CREATE VIEW ExpectationsView AS
SELECT ExpectationId
    ,ExpectationName
    ,(
       CASE 
          WHEN ExpectationOrganization_OrganizationId IS NOT NULL
                THEN (
                       SELECT OrganizationName
                       FROM Organizations
                       WHERE OrganizationId = ExpectationOrganization_OrganizationId
                       )
          WHEN ExpectationBeneficiary_BeneficiaryId IS NOT NULL
                THEN (
                       SELECT BeneficiaryName
                       FROM Beneficiaries
                       WHERE BeneficiaryId = ExpectationBeneficiary_BeneficiaryId
                       )
          ELSE (
                    SELECT TeamName
                    FROM Teams
                    WHERE TeamId = ExpectationTeam_TeamId
                    )
          END
       ) AS ParentName
FROM Expectations
GO

-- This index is needed for FTS index.
-- Note, I trust ExpectationId column is unique in your SELECT above,
-- if it's not, the below CREATE INDEX will fail and you will need to provide 
-- a new column to your VIEW which will uniquely identify each row, then use 
-- that PK-like column in the below index
CREATE UNIQUE CLUSTERED INDEX PK_ExpectationsView   
    ON ExpectationsView (ExpectationId);  
GO  

CREATE FULLTEXT CATALOG fts_catalog;  
GO  
CREATE FULLTEXT INDEX ON ExpectationsView  
 (
    ExpectationName Language 1033,   
    ParentName Language 1033
 )   
  KEY INDEX PK_ExpectationsView 
      ON fts_catalog;
      WITH (CHANGE_TRACKING = AUTO)
GO  

Once the Full-Text index which includes the relevant columns is there you can use FREETEXT or CONTAINS in queries:

SELECT ExpectationId, ExpectationName, ParentName FROM ExpectationsView
    WHERE FREETEXT(ExpectationName, @Keyword) OR FREETEXT(ParentName, @Keyword)

Note, the above code I've provided off the top of my head because I don't have data schema for your case so couldn't try running it. However, it should give you the general idea on how to proceed. HTH.