Database access system

Details Database access system Database access system

1998-06-24

2001-04-03

Breene, John (Department: 2777)

Data processing: database and file management or data structures

Database design

Data structure types

C707S793000, C707S793000

Reexamination Certificate

active

06212513

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a database access system and, more particularly, to a database that is capable of accessing an SQL database engine via CLI (Call Level Interface).
BACKGROUND OF THE INVENTION
In a prior database system that is accessible using a database access statement of SQL (Structured Query Language) or the like, an application program has had access thereto via middleware such as CLI or the like. One example of such middleware is ODEC (Open Database Connectivity) of the Microsoft Corp.
FIGS. 1 and 2
illustrate a configuration for implementing CLI in a database that may use an SQL database access statement. More particularly,
FIG. 1
illustrates a system of the client/server type, which implements the aforesaid CLI. In case of accessing an SQL server
120
from an application
112
on an SQL client
110
, an SQL instruction embedded within application
112
is sent to the SQL server
120
via an ODBC/CLI driver
114
. A database engine
122
on SQL server
120
executes the received SQL instruction to process data
130
and to return the processed result to application
112
via the ODBC/CLI driver
114
.
This is illustrated in
FIG. 2
in more detail. In
FIG. 2
, a search statement or an SQL update statement, pursuant to the protocol of ODEC/CLI and embedded in a unique language of the package software (application software)
112
, is rendered to be a universal SQL statement, which is then passed to the ODEC/CLI driver
114
. In this ODEC/CLI driver
114
, such a statement is transformed to an SQL dialect that is unique to a database to be accessed, which is then sent to SQL server
120
. Using this SQL dialect, database engine
122
on database server
120
processes data
130
.
Heretofore, an attempt has been made to extend an SQL database of the type that supports data comprising single byte characters (single byte character set: SBCS) alone, thereby enabling to support data comprising double byte characters (double byte character set: DBCS) such as Kanji or the like. For example, in the SQL defined by Japanese Industrial Standards (JIS), whenever DBCS data representing Kanji or the like is to be accessed, syntax different from that of SBCS is introduced. This is illustrated in
FIGS. 3
a
and
3
b.
In a database shown in
FIG. 3
a
, double byte data such as “D1D2” (where each of “Dl” and “D2” stand for a double byte character) or the like is stored as single byte data. In such a case, all data is accessed with the syntax of CHAR type.
FIG. 3
b
shows that if the database shown in
FIG. 3
a
is enhanced to support NATIONAL CHARACTER (NCHAR) or migrated to a new database which supports NATIONAL CHARACTER (NCHAR), it will be necessary to add “N” indicating NCHAR before literal of the data for accessing the corresponding data item. In another words, any syntax that is not provided with such “N” will result in an error.
However, in the conventional CLI, CHAR type has been defined as a sole data type. Namely, it has not been possible to specify NCHAR type and, thus, there has been no way to access any database having data of NCHAR type.
PROBLEMS TO BE SOLVED BY THE INVENTION
It is an object of this invention to transform, at a call device interface, an SQL statement of CHAR type to another SQL statement of another data type adequate for a database that is defined by a character string type other than CHAR type (a character string data type that is independently extended by a user, a character string type that requires syntax different from that of the standard character string type for accessing, or the like), whereby the database may be accessed using an SQL statement of CHAR type.
SUMMARY OF THE INVENTION
In order to accomplish the object, this invention is directed to a database access system for interfacing database access from an application, which comprises means for examining the literal of a database access statement passed thereto; means for transforming the database access statement to another database access statement adequate for the literal; and means for accessing a database using the another database access statement.
If the accessed result is erroneous, the transforming means transforms the another database access statement again to yet another database access statement adequate for the literal, thereby to access the database.
The transforming means repeats the transformation until transformation candidates are exhausted or a specified number of transformation candidates are transformed. Additionally, the database access system comprises transformation storage means for storing transformed information for each column, whereby the transforming means may perform the first transformation based on the information stored in the transformation storage means.
Further, this invention is directed to a recording medium for storing a program adapted for implementing functions of an interface in the database access system.
With such arrangement, there is no need to change an application or database even in a situation where a database system is extended to increase the number of data types to be accessed.


REFERENCES:
patent: 4949255 (1990-08-01), Gerth et al.
patent: 5724570 (1998-03-01), Zeller et al.
patent: 5893104 (1999-04-01), Srinivasan et al.
patent: 5918225 (1999-06-01), White et al.
patent: 5924089 (1999-07-01), Mocek et al.
patent: 5950188 (1999-09-01), Wildermuth
patent: 5987463 (1999-11-01), Draaijer et al.

Affiliated with

Also associated with

Rating

Database access system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Database access system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Database access system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2475675