公开(公告)号：BR8901648A

公开(公告)日：1989-11-21

申请号：BR8901648

申请日：1989-04-07

Applicant: IBM

Inventor： CHANG PHILIP YEN-TANG ,  ENGLES ROBERT WILLIAM ,  OBERMANN DAVID FRANCIS ,  TRUMBLE MARY KATHLEEN

IPC: G06F17/30 ,  G06F20060101 ,  G06F15/40

Abstract: A relational database system having mixed data comprises means for selectively designating a column in a database table as being for single byte character set data only. Preferably, the user application can specify the subtype of character data within a column as the column is created or added by specifying FOR SBCS or FOR MIXED in either the CREATE TABLE statement or the ALTER TABLE statement. This can be done by specifying the subtype of the character data types including CHAR, VARCHAR, and LONG VARCHAR. Along with specifying the subtype as either for single byte data or for mixed data, means are preferably provided for specifying the codepage to be used for the column of the table in the database. The subtype of the character can then be recorded in terms of the code page attributes of the character data type as stored in the database system catalogs. This encoding scheme provides an efficient method of determining whether a column is only for single byte character set data or mixed data, and at the same time knowing the correct codepage that is to be used for that column simply by querying the code page columns within the database system catalogs.