The collation attribute
is an optional attribute that specifies whether collation is based on the
territory specified for the database or Unicode codepoint collation. The valid
values for the collation attribute are:
- Unicode codepoint collation. This value is the default.
- Based on the language specified with the territory attribute. The default
collation strength for the locale is used. The default for
Derby is commonly TERTIARY,
in which character case is significant in searches and comparisons.
- Territory based with collation strength PRIMARY. Specify this value to make
Derby behave similarly to
many other databases, for which PRIMARY is commonly the default. PRIMARY
typically means that only differences in base letters are considered
significant, whereas differences in accents or case are not considered
- Territory based with collation strength SECONDARY. SECONDARY typically means
that differences in base letters or accents are considered significant, whereas
differences in case are not considered significant.
- Territory based with collation strength TERTIARY. TERTIARY typically means
that differences in base letters, accents, or case are all considered
- Territory based with collation strength IDENTICAL. IDENTICAL means that all
differences are considered significant.
Restriction: The collation attribute can be specified
only when you create a database. You cannot specify this attribute on an existing
database or when you upgrade a database.
If you specify the collation attribute with the value
TERRITORY_BASED, or one of its variants with a specific collation strength, the
collation is based on the language and country codes that you specify
with the territory attribute.
If you do not specify
the territory attribute when you create the database, Derby uses the java.util.Locale.getDefault method
to determine the current value of the default locale for this instance of
the Java Virtual Machine (JVM).
Note: The collation attribute
applies only to user-defined tables. The system tables use the Unicode codepoint
For information on how
Derby handles collation, see
"Creating a database with territory-based collation" and "Character-based
collation in Derby" in the
Derby Developer's Guide.
The following example shows the URL to create
the MexicanDB database. The territory attribute specifies
Spanish for the language code and Mexico for the country code. The collation attribute
specifies that the collation for the database is territory based.