公开(公告)号：PT90209B

公开(公告)日：1995-06-30

申请号：PT9020989

申请日：1989-04-06

Applicant: IBM

Inventor： CHANG PHILIP YEN-TANG ,  OBERMANN DAVID F ,  TRUMBLE MARY K

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.

公开(公告)号：CA1290455C

公开(公告)日：1991-10-08

申请号：CA589435

申请日：1989-01-27

Applicant: IBM

Inventor： CHANG PHILIP Y ,  ENGLES ROBERT W ,  OBERMANN DAVID F ,  TRUMBLE MARY K

IPC: G06F17/30 ,  G06F20060101 ,  G06F15/40

Abstract: AT9-88-010 In the relational database system of the present invention, an extension to the SQL language is provided to allow a user/application to specify whether a column in a database table contains only single byte character set data, or mixed single byte character set data and double byte character set data. Specifying whether a column contains single byte character set data or mixed data is achieved by specifying the subtype of the character data types including CHAR, VARCHAR, and LONG VARCHAR. 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. Along with specifying the subtype as either for single byte data or for mixed data, the user/application can further specify the codepage to be used for the column of the table in the database. Internally within the database manager of this invention, the subtype is 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.

公开(公告)号：PT90209A

公开(公告)日：1989-11-10

申请号：PT9020989

申请日：1989-04-06

Applicant: IBM

Inventor： CHANG PHILIP YEN-TANG ,  OBERMANN DAVID F ,  TRUMBLE MARY K

IPC: G06F17/30 ,  G06F20060101 ,  G06F

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.