Oracle’s regular expression support, which we introduced earlier in the book, manifests itself in the form of four functions, which are described in this section. Each function is usable from both SQL and PL/SQL.
All the examples in this section search text literals. We do this to make it obvious how each function works, by showing you both input and output for each example. Typically, you do not use regular expressions to search string literals, but rather to search character columns in the database, or character variables in PL/SQL.
For the same reason, the regular expressions in this section are simple to the extreme. We don’t want you puzzling over our expressions when what you really want is to understand the functions.