5. Working with QBF Operations : QBF Retrieve Operation : Search Qualifications : Bracketed Expressions
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Bracketed Expressions
By enclosing characters within brackets ([ ]), you can stipulate specific values in a pattern-matching search. For example, if you want to find employees whose last names begin with R or T, enter [RT]* in a Lastname field. This returns last names such as Randall, Rotelli, Tamatomi, and Tijerina. You can include any number of characters within brackets and they can be placed in any order.
All pattern-matching queries work in Query mode. However, if you invoke QBF with the ‑e flag (for expert mode) you cannot use bracketed pattern-matching operators for specifying selection criteria in an empty catalog in order to retrieve a set of tables or other objects for querying.
A bracketed pattern is often used when a table contains data in different cases. For example, if you entered S* as a query specification in the Dept field, a retrieve returns rows with Sales, but not rows with sales. However, the query specification [Ss]* returns all rows containing both Sales and sales. By separating characters with a hyphen and surrounding them with brackets, you can stipulate a range of characters for pattern matching. Thus, entering [A-M]* in the Name field retrieves the names of all employees whose last names begin with any letter in the first half of the alphabet, such as Alcott, Chung, Feldmann, King, and Moore. The wild card characters can be combined with bracketed expressions. Used either before or after the brackets, they further refine a search for patterns in data.