EMULATOR FOR AN SQL RELATIONAL-DATABASE

Abstract: Method and means for porting an existing application (An) using a relational-database with SQL interface toward a hardware platform (HW2) with a reduced software configuration which does not include an SQL relational-database. The invention emulates an SQL database enabling hardware resources saving and providing a subset of functions in order to: creating SQL tables and defining fields; storing, modifying and deleting data on created tables, with a type check, retrieving such data by using SQL filters. Functions can be subdivided into levels (M1, M2, M3) in order to: convert an SQL statement, coming from an existing user application (An), into a sequence of elementary interface functions (IF1...IFn), use said interface functions to read/write data files (F1...Fn), process output data to be supplied to the requesting user application (An).

Description: Emulator for an SQL relational-database The present invention relates to a method of providing a subset of SQL (Structured Query Language) relational-database functions to existing applications. There still exist a variety of commercially available databases with SQL interface, providing an exhaustive set of functions, but they are highly hardware resource ∞rjsu ing. As a result, computer programs written for one computer with a software platform including a commercial SQL relational-database are frequently unsuitable for use with computers having a reduced hardware configuration. In the past many existing applications had to be rewritten in order to enable them to interface with a proprietory database resident on that equipment. Furthermore proprietory databases are usually equipment dependent and cannot be used for the same or other applications on other equipment. One of the major problems that application developers are faced with when porting existing applications, developed on a different hardware and software platforms and using an SQL relational-database, toward equipment with reduced hardware configuration, for example communication servers, other network apparatus etc., is the need to rewrite part ofthe applications in order to enable them to interface with a proprietory database resident on that equipment, otherwise the appUcations could not be used or must be rewritten completely. Sometimes the destination equipment has a reduced avaϋabϋty of hardware resources because of the 'installation of other resource coiisuming appUcations (e.g., (communication software like ISO/OSI stack protocols, TCP/IP and others) and since commercial SQL relational-databases are highly hardware resources consuming it could be desirable to avoid installing h, for example in the case of the porting of an appUcation toward one or more communication servers. It wϋl be recognized that an SQL database running on any equipment with any configuration is essential in order to allow an existing appUcation using an SQL database to be ported toward an equipment and to function correctly, when a commercial database has not been instafled. It is an object ofthe present invention to provide a method and means of porting siφplying a set of SQL database functions to an existing appUcation on any equipment, without a significant consume of hardware resources. The object is attained by a method with the features according to claim 1 and by means of porting according to claim 4. The mvention as claimed enables the porting of existing user software appUcations using an SQL database toward any reduced hardware configuration on which a commercial resource consuming SQL relational-database cannot be installed, by only copying, recompiling and executing the appUcation files, without any source code modification. By using the invention, the waste of time to modify existing source code is avoided, where sometimes such source code is not easily modifiable and would require a big effort. Furthermore it is sometimes preferable to save hardware resources for other run time appUcations, in these cases the emulator object of the invention enables the saving in a configuration phase. Furthermore, the emulator can be istonrized to be used whh different platforms on any different equipment. Further advantageous features ofthe mvention are defmed in the subclaims. Advantageously, security of user data can be guarateed, when necessary, by using an encryption/decryption module to access data files. The invention will now be described in detail, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows the use ofthe emulator during a porting phase; Fig. 2 enumerate all parts which make up the software architecture ofthe emulator; Fig. 3 shows how an SQL statement is converted into an interface function which is then translated into a sequence of emulation library functions accessing the ASCII files; Fig. 4 shows the implementation of how an SQL statement is converted into an interface function which is then translated into a sequence of emulation library functions accessing the ASCII files; Fig. 4-B shows a special example of Fig. 4; Fig. 5 shows a system for managing a telephone network, implemented using a LAN network comprising corrimunication servers of reduced hardware configuration which can carry out the invention; and Fig. 6 shows an example of an increasing network topology comprising communication servers having a reduced hardware configuration which can carry out the invention. This invention focuses on a database emulation approach, as shown in Fig. 1. In what follows, particular attention will be paid to the service provided to the appUcation needing the database though it should be understood that emulator might implement a different set of functions which wiU be the rrjinimum required by the appUcation in order to work With the present invention an original method to provide the performances of an SQL commercial database in a different way is given, by using an emulator 1. Said emulator is a modular database: only the functions needed to satisfy the requirements of an existing user appUcation An are configured and installed, so to enable the rnaxirnurn flexibility in order to reduce the consumption of hardware resources, in particular memory and CPU time. The emulator manages configuration and user data ASCII files FL.Fn by using a modular Ubrary of functions and predefined data structures. The simple modular structure enables an easy configuration upgrade and maintenance, in order to reduce the emulator size taking into consideration the appUcation requirements and the hardware configuration of an equipment. Said appUcation An has, for example, been developed on a first hardware platform HW1 interfacing the appUcation An toward the SQL relational database with a software configuration SWl, and it is supposed to be used on a second harware platform HW2 where the SQL database is not available and thus SWl is not usable. The software architecture ofthe emulator 1 is shown in Fig. 2. The emulator 1 is composed ofthe followmg parts: - an Interface Module Ml providing the appUcations with an SQL interface (it takes the plase ofthe SWl platform). This module is appUcation dependent and should be customized depending on the type of SQL statements used, with particular regard to query statement having a complex syntax. It includes a set of functions, one for each specific SQL statement used by the appUcation An; - a modular Emulation Library M2, expandable and appUcation independent, including a set of functions performing basic operations on the ASCII files, invoked by Ml in order to implement the SQL statements used by the appUcation An; an error management module (not shown in the figure); an Encryption Module M3 (not mandatory); - configuration ASCII files including the database and tables definition Fl..Fm-l; and ASCII user data files Fm.Fn (which can be encrypted) including the user data inserted according to the tables definition. The emulator manages a number of ASCII files containing the tables definition and the user appUcations data. For security reasons data can optionally be encrypted. Using the emulator, the CPU time dedicated and the amount of RAM memory and hard disk number of Mbytes required is bightly reduced, compared to existing SQL databases. The SQL relational-database emulator provides the user appUcations with a modular Ubrary including a set of functions to: - creating SQL tables and defining fields; storing, modifying and deleting data on created tables, where a type check is performed according to the field definition; and retrieving such data by using SQL filters; The emulator implements the SQL commands in two different ways: 1. to define the database structure, the following table configuration commands can be implemented by using an editor to update configuration files: x create table * modify table configuration * drop table x description insert row to pre-populate the table 2. to use the defined database, the run-time modification of table content is realized by using the Module Interface functions IFl..IFn, as shown in Fig. 3 : select rows; insert one row; delete rows; update one row. This description will continue to take as an example an SQL database whose services are to be emulated. Before preceding to a detailed description ofthe invention, it would be helpful to outUne certain relevant aspects ofthe tables configuration phase. It will be described the manner in which the following SQL statements are handled: create table (H), modify table configuration (alter / drop / createXLULII), delete (alter / drop) (LIU), description (IV), insert row to pre-populate the table (V). The SQL syntax ofthe aforesaid statements is the followmg: I) to modify a database: ALTER DATABASE database_name; II) to define a new table structure: CREATE TABLE table_name (field namel NUMBER(9), field_name2 CHAR(14)); HI) to delete a table: DROP TABLE table name TV) to see the table definition: DESC table name V) data inserted as default: INSERT INTO tablejname (field_namel,field_name2) VALUES The aforesaid mentioned SQL statements can be emulated by using an ASCII configuration file written and modified by using an editor. For each new table an ASCII file is created. Each row defines a column ofthe table. The following is an example of table on an emulator table configuration ASCII file, where the first part is the table structure definition and the second part is the user data inserted as default. The characters "|", "-" and "*" are used to divide data. The character "#" mdicates that there is a comment line. In the first part the table structure is defmed The data included between H...H represents the table definition, and each row starting with a C is a column ofthe defined table. The specified parameters define for each table column the: x type, x lenght, x if the field can be null, if the field is a unique index to access to the records. In the second part of this example, rows with data are inserted into the table. A type check is performed accordmg to the previous table definition. # # Table ASH_STATES # H This table has 4 columns 141 # C AppUcation Service Id | NUMBER | 3 | NOT NULL | UNIQUE INDEX| C AppUcation Entity Name | CHAR | 32 | NOT NULL | UNIQUE INDEX| C Sequence Number | NUMBER | 3 | NOT NULL | UNIQUE INDEX| C State ame | CHAR | 20 | NOTNULL | | H #. # 1 1 dh_l 1 0 I IDLE I * 1 | dh_l | 1 1 STARTJNT_DIAL_PEND | * 1 | dh_l | 2 1 INT DIALJEXP | * 1 | dh_l | 3 I INT_DIAL_PEND | * 1 | dh_l | 4 1 WAIT_FOR_CONT | * 1 1 dh_l | 5 1 WAΓΓ_FOR_LAST | * 1 | dh_l | 998 I PROVIDER_ABORT | 1 | dh_l | 999 I SUCCESFUL_COMPLETED #- * 2 | bh_l | 0 I IDLE I * 2 | bh_l | 1 1 COMMAND EXPECTED 1 * 2 I bh l I 998 I PROVIDER ABORT | * 2 I bh_l I 999 I SUCCESFUL COMPLETED | The skiUed man wiU be aware of stifl fiuther configuration mode. By way of further explanation, reference is directed to Fig. 3 which is in diagrammatic form. An SQL statement, mcluded in the user appUcation, cause the activation of an emulator interface functions IFL which invokes a sequence, depending on the specific SQL statement, of emulation Ubrary fiinctions LFL.LFm accessmg the ASCII files AFl..AFk containing the user data. For example when the SQL stament INSERT INTO Tab2 (field name 1 ,field_name2) VALUES is mvoked by the user appUcation An, the INSERT emulator inter ace function IFI is activated; it caUs a sequence of emulation Ubrary functions accessmg the Tab2 ASCII file AF2 containing the user data, as it will be explained in more detail later. Another example is the following: when the SQL stament SELECT FROM Tab2 is invoked by the user appUcation An, the SELECTn emulator interface function BFn is activated; h calls a sequence of emulation Ubrary functions accessing the Tab2 ASCII file. A modular emulation library is available providing a set of functions LFL.LFm. A subset of of said functions can be combined to implement an SQL statement. An example of Ubrary functions is the foUowing: Fl _get_table_descr F2 open table F3 close table F4 _search_first_row F5 _search_next_row F6 _fetch_row_at_curr_pos F7 _fetch_row_at_abs_pos F8 write row F9 delete row F10 refresh table file A detailed description of each function is provided later. In Fig. 4 it is shown in details the implementation of one of the interface functions IFL.IFn aforesaid listed and shown in Fig. 3. Said function is translated into a sequence of emulation Ubrary functions LFL.LFm accessmg the ASCH files. Table Description A and Access Description B are defmed in the data area ofthe function IFi; they are implemented as an array of records having an element for each database table column. Table Description A is build up ofthe foUowing configuration data: 1 = column type, 2 = column lenght, 3 = whether the field can be null or not, 4 = whether the field is an index to access to the records or not. Access Description B includes data about the access type and mode depending on the origin SQL statement type. It is build up ofthe following data, filled in by the emulator Interface Function IFi depending on which columns the SQL statement uses: 1 = use flag to indicate if the column is used (T=true, F=^false), 2 = string size, and the followmg fields where to read/write the result ofthe operation (written by the fetch row or read by the _write_row ): 3 = a flag indicating whether the field can be null or not (T=true, F=false), 4 = a flag indicatmg whether the field contams a numeric value, 5 = a flag indicating whether the field contains an alphanumeric value (char=chararter/ptr=pointer). The first operation performed in RAM memory is the _ et_table_description function activation to retrieve from the database files the user table definition and copy it in the Table Description A Subsequently all the emulator Ubrary functions wifl use the Table Description A to read write the Access Description B. An example of a system to manage a telephone network, implemented using a LAN network comprising communication servers of reduced hardware configuration which can carry out the invention, is shown in fig 5. The system mcludes two AppUcation Servers ASI and AS2, one active the other stand-by, performing management operations for a network; these equipment have a full hardware and software configuration including dupUcated disks HD. An Operator can interface the management system by using a socaUed X Terminal connected to a X Terminal Server providing a graphical operator interface. A pluraUty of possible Communication Servers CSL.CSn of reduced hw configuration are installed and can carry out the invention. The number of communication servers CSL.CSn with different hardware configuration can increase in future upgrades of the network On the communication server CS should be instafled appUcations developed on different hardware configuration equipment having a complete software platform including a commercial database. As the reduced communication server CS software platform should include also COmmunication software and since commercial SQL relational-databases are highly hardware resources consuming, the emulation approach enables to spare memory and CPU time. In fig 6 is shown an example of a telephone network management system architecture comprising network management systems according to Fig. 5, including equipment which can carry out the invention. The emulator approach can be useful in view of future extention of the network by inserting an increasing number of equipment of different hardware configuration on which appUcations needing an SQL relational-database should be executed As the complexity of a network topology increases, the network management "systems are supposed to be upgraded in terms of number of equipment installed and appUcations running on said equipment. The architecture ofthe network management system shown in Fig. 5 can be split up in a plurality of cooperating sub-systems interconnected through a network Network management systems SYSTEM 1 SYSTEM2 and SYSTEM3 including equipment having different configuration are interconnected to a network to be managed in order to cooperate exchanging management mformation. The emulation approach enables the porting of appUcations developed on full hardware and software platforms toward any network equipment. It has been mentioned above that every interface function IF .IFn aforesaid listed and shown in Fig. 3, is translated into a sequence of emulation Ubrary functions LFL.LFm accessing the ASCII files. By way of further explanation, an SQL statement in the user appUcation is converted into a IF function each IF function is associated to a sequence of functions ofthe emulation Ubrary, where the sequence depends from the SQL statement the output ofthe SQL command is retumed to the user appUcation, as described above. In the followmg will be examined in more detail: 1) IF functions 2) emulation library 3) ASCπ files An example of set of IF functions can be the following: insert; delete; - update; selectl; ...; and selectn. A SELECT statement, according to SQL syntax, can have a different WHERE clause. Here are some examples of different complexity. The character "*" means "ALL". SELECT fl, £2 FROM tabl; SELECT * FROM tabl; SELECT fl,£5 FROM tab 1 WHERE(fl=0 AND f2= , string'); SELECT fl,β FROM tabl WHERE(F1=0 AND £2 NOT IN (SELECT D,f4 FROM tab2 WHERE (fl=10 AND fZ^stiingl'))); ( (SELECT fl,β FROM tabl WHERE(F1=0 AND £2 NOT IN (SELECT β ,f4 FROM tab2 WHERE (fl=10 AND ) UNION (SELECT fl,f5 FROM tabl WHERE(F1=0 AND f2 NOT IN (SELECT £3,f4 FROM tab2 WHERE (fl=10 AND G^shingl'))); ) ); The user appUcation An mterfaces the database using SQL statement and passing parameters (pomters to data structure containing data sent to the database and pomters to data structure in which the output ofthe SQL commands wfll be returned). There wfll described one ofthe aforesaid IF function, the one correspondent to the SELECT SQL statement, as far as hs implementation is concemed TAB 1 is an example of database table having 6 columns defined C1..C6. Two data Unes have been inserted in TABl; only the data relevant for the example are written, the other field can have any value. TAB Cl C2 C3 C4 C5 C6 5 70 0 string 10 100 200 string The following SQL statement can come from the user appUcation An: SELECT c2,c4,c5 FROM tabl WHERE(c2=10 AND c6= , string'); There will be described how the emulator works to get results. In this SELECT statement with this WHERE clause, the Access Description Table B defined in fig 4, is dupUcated in - Access Descrφtion Select B 1 (not shown in figure), Access Description Where B2 (not shown in figure). In this case two different accesses to user data are made by using two Access Description tables. As explained before, every row ofthe Table Descrφtion A and Access Description B or Bl and B2 corresponds to a column ofthe defmed database table at the creation phase. The Access Descrφtion Select Bl defines which fields among C1..C6 are to be retrieved for each data row selected from the ones present in TABl and should be sent to the appUcation An, by tagging with T the fields of interest, in this case cl,c4,c5: 1 2 3 1 4 use Cl F C2 T 10 C3 F C4 T 100 C5 T 200 C6 F The Access Descrφtion Where B2 defines the clause to identify which rows present in TABl should be selected, by tagging with T the fields cited in the WHERE(c2=10 AND clause: 1 2 3 4 5 use Cl F C2 T 10 C3 F C4 F C5 F C6 T 5 string Another solution in a different SELECT statement, for example SELECT fl, £2 FROM tabl; could be performed by using a single access and a single Access Descrφtion B. In Fig. 4-B is shown a special case of Fig. 4. This is the case ofthe implementation ofthe following SQL statement. ( (SELECT fl,β FROM tab 1 WHERE(F1=0 AND £2 NOT IN (SELECT £3,f4 FROM tab2 WHERE (fl=10 AND firstling 1'))) ) UNION (SELECT fl,β FROM tab 1 WHERE(F1=0 AND £2 NOT IN (SELECT £3,f4 FROM tab2 WHERE (fl=10 AND ) ); which could be performed by using: a multiple Table Description Al and A2 a multiple Access Descrφtion B 1 and B2. In the following paragraph it will be explained how different steps are executed by the IFn SELECT function, by cafling a definite sequence of emulator library functions. When the user appUcation An asks the IFn for retrieving data from the database, it sends to the emulator a pomter to a data structure containing parameters ofthe SQL SELECT statement and at the end ofthe operation will be given back a pomter to the retrieved data result ofthe query. A way for the IFn to perform the aforesaid task is the following: 1) the Table Description A, in the data area of Fig. 4, is initialized according to the table descrφtion read from the ASCII file containing the configuration data, by cafling the emulator Ubrary function get_table_descr() LF in particular the array of stmct of Table Descrition A is filled in, one row for each table column; 2) the ASCII file containing user data related to the previously accessed table configuration is opened the fimction verify whether the file has not been opened before. If the file is opened for the first time: - opens the file - moves to the first row by callmg the function _search_next_row(). If not, a pomter to the file moves to the row by cafling _search_next_row() and retum a pointer to the row, cycling tϋL .. the end ofthe file, or .. the specified number of rows has been read; 3) for each row, it reads the row at current position by cafling the function _fetch_row_at_curr_pos() and verify if the WHERE clause written in B2 is satisfied for that row, in this case the required fields of that user data row are copied in Bl (SELECT Access Descrφtion), filling in the last three columns (nufl, long int, char/ptr) accordmg to the data type; 4) at the end close the user data table file. As result of this function, the output ofthe SELECT clause will be available in the Access Descrφtion table (last three columns of B 1) and will be retumed to the appUcation An. An example of EMULATION LIBRARY, as listed above, can be the following. A subsetof the functions can be combined to implement an SQL statement. In the following, a more detailed description of each function is given. Fl NAME : _ et_table_descr DESCRIPTION : It gets the table description for a specified table (input parameter table name), filling in the "row descrφtion" structure (output parameter row desc). The proper table file is opened and closed after the completion ofthe table description reading. It logs a message when an error occurs. F2 NAME : _open_table DESCRIPTION : It opens a table file for a specified table (input parameter table name). The file can be opened for read, update or append depending on the specified "action type" (SELECT, DELETE and INSERT as specified by the input parameter _action_type).It gives back to the cafling function the pomter to the opened file (output parameter _file_ptr). It logs a message when an error occurs. F3 NAME : close table DESCRIPTION : It closes a table file for a specified table name (input parameter table name). The file pomter is given by the cafling function (input parameter _file_ptr). It logs a message when an error occurs. F4 NAME : search first row DESCRIPTION : It searches for the first row in a table. That means: the Table Descrption lines are skipped, as comment lines, till the second Header Une (closing the Table Descφtion) is found. It gets from the cafling function the file pomter (input parameter file_ptr) and the table name (input parameter _table_name) that is inserted in the error messages. If the row is correctly found it gives back to the cafling function the position ofthe row in the table file (output parameter _fϋe_pos): it is the position ofthe line type char. It assumes the initial value ofthe file pointer is pointing to the first byte of a file Une, otherwise the search fails. Last char got from the file: - first char ofthe row (when it has been correctly found) - end-of-file found at the beginning of a line (no rows in the table) - an unexpected line first char - an unexpected end-of-file. It logs a message when an error occurs. F5 NAME : _search_next_row DESCRIPTION : It searches for the next row in a table. That means: Table Descrφtion lines, if found, are treated as "unexpected Unes". It gets from the cafling function the file pomter (input parameter file ptr) and the table name (input parameter _table_name) that is inserted in error messages. If the row is correctly found, it gives back to the cafling function the position ofthe row in the table file (output parameter _file_pos): it is the position ofthe line type char. It assumes the initial value ofthe file pomter is pointing to the first byte of a file tine, otherwise the search fails. Last char got from the file: - first char ofthe row (when it has been correctly found) - end-of-file found at the beginning of a Une (no more rows in the table) - an unexpected Une first char - an unexpected end-of-file. It logs a message when an error occurs. F6 NAME : _fetch_row_at_curr_pos DESCRIPTION : It fetches a table row starting from the current position in the table file (position given by the cafling function in the file pomter _file_ptr). To scan the row it uses the row description given by the cafling function in the input parameter _row_desc. It fifls in the "access stmcture" in the memory area ofthe cafling function (parameter _row_access). For more details, See the internal function _fetch_row. It logs a message when an error occurs. F7 NAME : _fetch_row_at_abs_pos DESCRIPTION : It fetches a table row starting from the position expUcifh/ given by the cafling function with the input parameter _file_pos (in addition to the file pointer _ffle_ptr). To scan the row it uses the row description given by the cafling function in the input parameter _row_desc. It fifls in the "access stmcture" in the memory area ofthe cafling function (parameter row access). For more details, See the intemal function fetch row. It logs a message when an error occurs. F8 NAME : write row DESCRIPTION : It logs a message when an error occurs. Input: A and B. It inserts a row in a table (the row is appended at the bottom ofthe file table). It uses the row descrφtion given by the cafling function as input parameter. It takes the data to be written from the Access Descrφtion structure B given by the cafling function as input parameter. It opens and close the table file. It checks whether a row with the UNIQUE INDEX already exists in the table F9 NAME : _delete_row DESCRIPTION : It logically deletes a row in a table. The cafling fimction must give the position ofthe row in the table. It updates the counter of deleted Unes. F10 NAME : refresh table file DESCRIPTION : It checks, for a specified table, whether the deleted lines counter has reached the threshold or not. If yes, rewrites the table files without au lines that have been previously logically deleted The counter is reset to 0 when the threshold is overcome and maintaines the same value when the value is less than the threshold Fil NAME : fetch row DESCRIPTION : It fetches a table row starting from the current position in the table file (position given by the cafling function in the file pointer ffle_ptr). To scan the row it uses the row descrφtion given by the cafling function in the input parameter _row_desc. It fifls in the "access structure" in the memory area ofthe cafling function (parameter _row_access). It gets from the cafling function the table name (parameter table name) and the row number (parameter row nbr) that are inserted in the error messages. If no error occurs, the scanning terminates at the end-of-Une after the last column. Otherwise, the scanning is aborted when the first error is detected. It assumes the initial value ofthe file pointer is pointing to char immediately after the special char initiating the row. Last char got from the file: - end-of-Une terminating the last (or the unique) line composing the row (fetching successfully teiminated), - column terminator of the last column fetched or bad char initiating a Une or unexpected end-of-Une or unexpected end-of-file (fetching aborted). It logs a message when an error occurs. The described method of emulating an SQL relational-database in order to simplify the porting of an existmg appUcation toward a destination equipment is felt to have considerables advantages in terms of memory and CPU time saving.

Claims: CLAIMS 1. A method of providing a subset of SQL relational-database functions to an existing appUcation, comprising the following steps: - creating SQL tables and defining fields; storing, modifying and deleting data on created tables, where a type check is performed accordmg to the field definition; and retrieving such data by using SQL filters; wherem memory and CPU time is minimized by reducing the size of the database in a configuration phase as required, and wherem provided functions can be subdivided into different levels in order to: x convert an SQL statement, coming from an existmg user appUcation (An), into a sequence of elementary interface functions (IFL.IFn), x use said interface functions to read/write data files (FL.Fn), x process output data to be suppUed to the requesting user appUcation (An). 2. A method as claimed in claim 1 wherein the created SQL tables including field definitions are stored in configuration ASCII files (FL.Fm-l) and the user data are stored in ASCII user data files (F .Fn). 3. A method as claimed in claim 1 wherem user data files are encrypted accordmg to an algorithm in order to guarantee secrecy and access to data are handled by an encryption/decryption module (M3). 4. Means of porting an existing appUcation using an SQL relational-database toward reduced hardware configuration equφment (HW2) on which the method of claim 1 is carried out, sirrφUfying the porting phase by only: x copying, x recompiling, executing the appUcation files. 5. Means of porting according to claim 4, wherem a subset of SQL functions to be provided, can be configured and reduced or increased as needed by the existmg user appUcation (An).

Inventors: BONZI RODOLFO, BONZI, RODOLFO
Applicants: ALCATEL NV, BONZI RODOLFO, ALCATEL N.V., BONZI, RODOLFO
Application year: 1996
Main classification: G06F17
IPC codes: G06F12, G06F17