#Collate vs non collate code

In an SQL query, you can specify a collation function without parentheses %SQLUPPER Name or with parentheses %SQLUPPER(Name). There are also various legacy collation types, the use of which is not recommended. A non-numeric string value is returned as 0. MINUS - Makes the value numeric and changes its sign.

#Collate vs non collate code

your definitions and code may be easier to maintain if you use TRUNCATE only when you have a length defined and EXACT when you do not. If you do not specify a length for TRUNCATE, it behaves identically to EXACT while this behavior is supported. It takes a positive integer argument, in the form %TRUNCATE( string, n ), to truncate the string to the first n characters, which improves indexing and sorting on long strings. This is useful when indexing exact data that is longer than what is supported for use in a subscript. TRUNCATE - Enforces case sensitivity for string data and (unlike EXACT) allows you to specify a length at which to truncate the value. Note that the SQLUPPER transform is not the same as the result of the SQL function UPPER. SQLUPPER supports an optional maxlen integer value. This transformation also causes SQL to collate the SQL empty string ('') value and any value containing only whitespace (spaces, tabs, and so on) as a single space character. The reason this space character is prepended is to force numeric values to be collated as strings (because the space character is not a valid numeric character). SQLUPPER - Converts all alphabetic characters to uppercase, strips trailing whitespace (spaces, tabs, and so on), and then adds one leading space character to the beginning of the string. SQLSTRING supports an optional maxlen integer value. It collates any value containing only whitespace (spaces, tabs, and so on) as the SQL empty string. SQLSTRING - Strips trailing whitespace (spaces, tabs, and so on), and adds one leading blank space to the beginning of the string. Because canonical numbers collate before strings, including single characters and non-canonical numeric strings, EXACT is generally not recommended for string data that may contain values in canonical numeric format (for example 123 or -.57). String collation includes non-canonical numbers (such as 088) and mixed numeric strings (such as 22 Elm Street). Collates canonical numbers in numeric order, then collates strings in character-by-character ASCII order. The % prefix is required when specifying a collation function.Ĭollation is in ascending ASCII/Unicode sequence, with the following transformations:ĮXACT - Enforces case sensitivity for string data without adding or stripping characters. Collation TypesĬollation can be specified as a keyword in the definition of a field/property or the definition of an index.Ĭollation can be specified by applying a collation function to a field name in a query clause. You can use the ObjectScript Sorts After operator to determine the relative collation sequence order of two values.Īlso see “ SQL Collation and NLS Collations,” later in this chapter. However, because a timestamp is in ODBC format, the string collation is the same as chronological sequence, if leading zeros are specified.Ī string expression (such as those using the scalar string functions LEFT or SUBSTR) makes its result collation EXACT.Īny comparison of two literals uses EXACT collation. This conversion is for the purposes of collation only in InterSystems SQL strings are usually displayed in uppercase and lowercase letters, regardless of the collation applied, and the length of a string does not include the prepended space character.Ī timestamp is a string, and therefore follows the current string collation. SQLUPPER collation converts all letters to uppercase (for the purpose of collation), and prepends a space character to the beginning of the string. The default string collation is SQLUPPER this default is set for each namespace.

This creates an order such as the following: null, A, AA, AAA, AAB, AB, B.

String collation orders strings by collating on each sequential character.

Numeric collation orders numbers based on the complete number in the following order: null, then negative numbers from largest to smallest, zero, then positive numbers from smallest to largest. There are two fundamental collations: numeric and string. Table Field/Property Definition CollationĬollation specifies how values are ordered and compared, and is part of both InterSystems SQL and InterSystems IRIS® data platform objects.