1 1 4 NVarChar

1.1.4 NVarChar

NVarChar is a variable-length character field, with a maximum length between 1 and 65,535. (This is the number of characters, not the byte length.)

NVarChars store alpha data of any codepage. For example, in a list, an NVarChar field may have Japanese in one row, and French in another row.

NVarChars are classified as unicode strings.

An NVarChar retains any trailing blanks, they are significant. When concatenating an NVarChar with spaces on the end, those spaces are retained. But the space is NOT SIGNIFICANT for comparisons.

Please review the general 1.1.1 Field Type Considerations.

Field Definition Rules

Rules for defining an NVarChar field in the repository are:

Usage Rules

Usage Notes

• Working fields may be defined as TYPE(*NVARCHAR).

• A NVarChar of zero length has a space added to it before inserting or updating the database via Sql. This is in order to obtain consistent behaviour between our databases. Without a space, Oracle interprets the data as being SQL Null, which is not strictly true and is not how the other databases behave.

     So, be aware that your application cannot make a distinction between an empty NVarChar and a NVarChar with 1 blank. Also, concatenations of a zero length NVarChar before inserting to the database and after reading may differ by the extra space. Behaviour can be made consistent by truncating trailing spaces before using NVarChars in an expression. Note that when comparing an empty NVarChar in RDML to an NVarChar with 1 space read from the database they will compare equal because trailing spaces are not significant in comparisons - they are only significant in expressions, like concatenation.

Platform Considerations

• Refer to Platform Considerations in 1.1.1 Field Type Considerations.

Tips & Techniques

• If there is no need to support multiple languages at execution time, use an Alpha field or a String field.

Also See

1.1.2 Alpha

1.1.3 String

Ý 1.1 Field Types