For example, in Danish, Р“вЂ is after Z, while Y and Р“Сљ are considered to be variants of the same letter.Р”В¬ollation can be case-sensitive or case-insensitive. In addition, different cultures or countries that use the same alphabets may sort words differently. In contrast, binary collation orders strings based on their binary representation (character encoding), treating each string as a simple sequences of bytes.Р”Вifferent languages have different collations. They order strings in the same way as dictionaries, phone directories, and other text lists written in a given language. Collations that take into consideration the standards and customs of spoken languages are called linguistic collations.

There are many possible collations that can be applied to strings to determine their ordering. For example, the ORDER BY clause uses collation to determine the ordering of strings to sort the query results, while PL/SQL uses collations to sort strings in associative arrays indexed by VARCHAR2 values, and the functions MIN, MAX, GREATEST, and LEAST use collations to find the smallest or largest character value. The ordering of strings in a set is called sorting. Note that Oracle Text provides advanced full-text searching capabilities for the Oracle Database. This chapter uses the term matching to mean determining the equality of entire strings using the equality operator = or determining the equality of substrings of a string when the string is matched against a pattern using LIKE, REGEXP_LIKE or REGEXP_INSTR. SQL operators and functions used in searching are =, LIKE, REGEXP_LIKE, INSTR, and REGEXP_INSTR. In the Oracle documentation, the term sort is often used in place of collation.Р”Вetermining equality is especially important when a set of strings, such as a table column, is searched for values that equal a specified search term or that match a search pattern. For any two strings, the collation defines whether the strings are equal or whether one precedes the other in the sorting order. The process of determining the mutual ordering of strings (character values) is called a collation. This chapter explains the mechanism of linguistic sorting and searching of character data or strings in Oracle Database.

Regular expression not exceed length