Vendor database character sets and the Rational ClearQuest data code page

The vendor database character set describes the setting for the database management system (DBMS) that determines which characters can be stored in the database.

DBMS vendors use a variety of terms to describe their character sets. The next table lists the alternate terms used by DBMS vendors who support Rational® ClearQuest®

Database management system	Vendor database character set synonyms
DB2®	code page, code set
Oracle	character set, charset
SQL Server	code page, collation

The Rational ClearQuest data code page setting determines which characters are written to the database.

Each Rational ClearQuest data code page has a corresponding vendor database character set for each supported vendor database (Oracle, DB2, SQL Server). This data code page is a subset of the corresponding vendor database character set. For a list of supported character sets for each vendor database and the corresponding Rational ClearQuest data code pages, see Supported vendor database character sets.

Before you set up your database management system to be used with Rational ClearQuest, you must choose the Rational ClearQuest data code page to set for your schema repository and user databases. For more information, see Guidelines for selecting a Rational ClearQuest data code page. When you set up your database management system, assign a vendor database character set value that corresponds to the Rational ClearQuest data code page you selected. All databases in a database set must have the same vendor database character set.

If you configure your database management system with a vendor database character set that does not support the Rational ClearQuest data code page you selected for the schema repository, you cannot set the data code page. Therefore, you must always know the value of the data code page value is before you create and configure a vendor database to use with a Rational ClearQuest schema repository.

In general, set the Rational ClearQuest data code page and the vendor database character set to the corresponding values in Supported vendor database character sets.

However, the Rational ClearQuest data code page and the vendor database character set can be different from the values listed in Supported vendor database character sets, if both of these conditions are true:

The characters of the Rational ClearQuest data code page are a subset of the characters of the vendor database character set.
The database currently contains only the characters supported by the Rational ClearQuest data code page.

For example, it is possible to use the Rational ClearQuest data code page 20127 (ASCII) with SQL Server database code page 1252 (Latin-1). The database can store all the characters that are valid in the data code page because ASCII is a subset of Latin-1.

However, because these situations are so variable, the safest practice is to set the Rational ClearQuest data code page and the vendor database character set to the corresponding values.

Validating the vendor database character set

The Rational ClearQuest data code page value is validated against the value of the vendor database character set when you perform these tasks:

Create a schema repository and set the Rational ClearQuest data code page.
Use the Maintenance Tool to change a schema repository's data code page value.
Set or change the data code page value for a schema repository by using the installutil command.

For example, a Rational ClearQuest administrator can create an empty Oracle database, configure its character set to WE8MSWIN1252, and then use the Maintenance Tool to create a schema repository that uses the corresponding 1252 (Latin-1) data code page and the new Oracle database.

Compatibility with existing database sets

You might be required to change your previous vendor database character sets to support data from your preferred Rational ClearQuest data code page. To change the vendor database character set of existing databases, you might have to move the old data into new databases. If your existing data is not supported by one of the Rational ClearQuest data code pages, you must first convert the data to values in one of the supported code pages. Some database vendors provide tools that you can use to analyze and convert your data. You can also use the codepageutil command to analyze your data.