_ (Wildcard - Match One Character) (Transact-SQL)
Applies To: Azure SQL Database, SQL Server (starting with 2008)
Matches any single character in a string comparison operation that involves pattern matching, such as LIKE and PATINDEX.
The following example uses the _ operator to find all the people in the Person table, who have a three-letter first name that ends in an.
-- Uses AdventureWorks SELECT FirstName, LastName FROM Person.Person WHERE FirstName LIKE '_an' ORDER BY FirstName;