Overcoming Limitations: Performing Leading Wildcard Searches in SQL Server's Full-Text Search

This approach lets you achieve leading wildcard searches but adds some complexity:

1. Maintaining an extra column for reversed text.
2. The search query needs to be reversed as well.

CREATE TABLE MyTable (
  ID int PRIMARY KEY,
  TextData nvarchar(max),
  ReversedText nvarchar(max) AS REVERSE(TextData) PERSISTED
);

CREATE FULLTEXT INDEX IX_MyTable_ReversedText ON MyTable(ReversedText);

This code creates a table named MyTable with two columns:

• ReversedText: A calculated column that stores the reversed version of TextData. The PERSISTED keyword ensures the reversed text is stored in the database.
• TextData: The original text data.
• ID: An integer primary key.

Inserting Data:

INSERT INTO MyTable (ID, TextData)
VALUES (1, 'This is some text to search');

This code inserts a sample record into the table.

Full-Text Search with Leading Wildcard:

DECLARE @searchTerm nvarchar(max) = 'value*';

SELECT *
FROM MyTable
WHERE CONTAINS(ReversedText, QUOTEME(@searchTerm));

This code:

• Wraps the search term in QUOTEME to ensure the asterisk is treated as a wildcard and not a multiplication operator.
• Filters the results using CONTAINS with the reversed column ReversedText.
• Uses a SELECT statement to retrieve data from MyTable.
• Defines a variable @searchTerm with the search term "*value".

This method uses the LIKE operator with pattern matching characters:

• _: Matches a single character.
• %: Matches any sequence of characters (including zero).

While not as flexible as a wildcard at the beginning, you can achieve similar results for specific patterns.

Example:

SELECT *
FROM MyTable
WHERE TextData LIKE 'val_%';

This query will find rows containing "value", "valid", "valley", etc.

Breaking Down the Search Term:

If the search term consists of separate words, you can break it down and use OR conditions in your WHERE clause.

SELECT *
FROM MyTable
WHERE TextData LIKE '%value%' OR TextData LIKE '%able%';

CLR Functions (For Advanced Users):

For more complex scenarios, you can create a Common Language Runtime (CLR) function in a .NET language like C#. This function could perform custom parsing and searching logic on the text data.

External Search Engine Integration:

Consider integrating with a dedicated search engine like Apache Solr or Elasticsearch. These tools excel at full-text search functionalities, including leading wildcards and other advanced features. They can connect to your SQL Server database and provide a more robust search experience.

Choosing the Right Method:

The best method depends on your specific needs:

• Advanced Needs: CLR functions and external search engines provide greater control and capabilities but require more development effort.
• Flexibility: Breaking down the search term works well for searches with separate words.
• Simplicity: LIKE with pattern matching offers a straightforward approach for basic leading character searches.