Collations control character ordering and comparison operations during Teradata Database sessions.
Collations are designed as single level or two level. A two-level collation orders character strings according to a two-level comparison.
Characters are first partitioned into equivalence classes that have the same collating value. The relative ordering of classes and characters within a class is significant.
- All characters in a class have the same collation value.
- A character from class i is less than any character from class i+1.
The process is as follows:
- Convert characters in the strings to be compared into equivalence classes.
- Compare the strings.
IF the strings are… THEN processing … not equal stops. equal continues.
- Order characters within each class using criteria defined for the collation sequence, and compare.
The MULTINATIONAL Norwegian standard collation sequence is an example of a two-level collation.