SQL Full-text index

SQL Full-Text Index is a feature in relational database management systems (RDBMS) that allows efficient and powerful searching of text data stored in database columns. It provides advanced search capabilities, including searching for keywords, word variations, and proximity of words within a document.

To create a full-text index in SQL, you need to follow these general steps:

Identify the table and column(s) that contain the text data you want to index.
Create a full-text catalog (a logical storage container for full-text indexes) if it doesn’t already exist.
Create a full-text index on the specified table and column(s) using the appropriate syntax.
The syntax for creating a full-text index varies slightly depending on the RDBMS you are using. Here are examples of the syntax for creating a full-text index in Microsoft SQL Server.


-- Create a full-text catalog

-- Create a full-text index on a table and column(s)
CREATE FULLTEXT INDEX ON table_name (column_name)
   KEY INDEX index_name
   WITH (FULLTEXT CATALOG catalog_name);

In example, catalog_name is the name of the full-text catalog, table_name is the name of the table to be indexed, column_name is the name of the column(s) containing the text data, and index_name is the name of the full-text index.

Once the full-text index is created, you can use various SQL statements to perform searches against the indexed data. Here’s an example query that searches for documents containing specific keywords using the CONTAINS predicate:

SELECT column_name1, column_name2, ...
FROM table_name
WHERE CONTAINS(column_name, 'keyword1 AND keyword2');

This query retrieves rows from the specified table where the indexed column(s) contain both “keyword1” and “keyword2”. You can also use other predicates like FREETEXT or CONTAINSTABLE depending on the RDBMS you’re using and the specific search requirements.

SQL Full-Text Indexing is a powerful feature that can significantly improve the performance and accuracy of text-based searches in databases, enabling users to find relevant information more efficiently.