Oracle Text supports case-sensitivity for word and ABOUT queries.
Word queries are not case-insensitive by default. This means that a query on the term dog returns the rows in your text table that contain the word dog, but not Dog, or DOG.
You can enable or disable case-sensitive searching with the MIXED_CASE attribute in your BASIC_LEXER index preference. With a case-sensitive index, your queries must be entered in exact case. For example, a query on Dog matches only documents with Dog. Documents with dog or DOG are not returned as hits.
To enable case-insensitive searching, set the MIXED_CASE attribute in your BASIC_LEXER index preference to NO.
Stopwords and Case-Sensitivity
If you have case-sensitivity enabled for word queries and you enter a query on a phrase containing stopwords and non-stopwords, then you must specify the correct case for the stopwords. For example, a query on the dog does not return text that contains The Dog, assuming that the is a stopword.
ABOUT queries give the best results when your query is formulated with proper case. This is because the normalization of your query is based on the knowledge catalog which is case-sensitive. Attention to case is required especially for words that have different meanings depending on case, such as turkey the bird and Turkey the country.
However, you need not enter your query in exact case to obtain relevant results from an ABOUT query. The system does its best to interpret your query. For example, if you enter a query of ORACLE and the system does not find this concept in the knowledge catalog, the system might use Oracle as a related concept for look-up.