Embed Size (px)
Citation preview
IBM’s statements regarding its plans, directions, and intent are subject to change or withdrawal without notice at IBM’s sole discretion. Information regarding potential future products is intended to outline our general product direction and it should not be relied on in making a purchasing decision. The information mentioned regarding potential future products is not a commitment, promise, or legal obligation to deliver any material, code or functionality. Information about potential future products may not be incorporated into any contract. The development, release, and timing of any future features or functionality described for our products remains at our sole discretion.
Disclaimer
IMS 13 SQL support for COBOL
• Target Market
– IMS TM and DB customers who would like to write or modify IMS
COBOL applications to access IMS data using SQL
• Challenge Addressed
– No SQL access to IMS data from IMS COBOL applications
– Lack of DL/I skills in AD community
• Solution Statement
– Enable SQL calls from COBOL applications in addition to the current
Java-based solutions
• Business Value
– Expands IMS database access for application and database developers
– Reduce application development cost by leveraging existing SQL skills
– Provide a consolidated native SQL engine as the foundation of existing
and future client exploitation
Prerequisites
• Software requirements
– IMS 13 + PTF UK98028
– IMS Catalog function is required
– COBOL compiler with IMS co-processor function
• Enterprise COBOL Developer Trial z/OS V5.1 or
• Enterprise COBOL for z/OS V5.1 + APAR PM92523
– Note: COBOL V5.1 requires z/OS 1.13 and above
• Hardware requirements
– Same as IMS 13 and COBOL V5.1
• SQL support for COBOL
– Offer SQL as a query language for COBOL programs to access IMS
database in addition to DLI
• SELECT/INSERT/UPDATE/DELETE
– EXEC SQLIMS as the interface to execute IMS SQL calls
• SQL processor in IMS
– Process SQL calls natively by the IMS subsystem
– Still perform DLI database call processing underneath
– Provide a consolidated way for SQL processing
– Uses database metadata in IMS Catalog
• Support IMS TM/DB (MPP, IFP, BMP) and DBCTL BMP
Solution Highlights
IMS SQL concepts
What is SQL?
• SQL stands for Structured Query Language
– SQL is a standard and is well defined
– Most common database language for relational databases
– Support for SQL can be found in programming languages
such as Java, .NET, C++, COBOL, PL/I, etc
• IMS and SQL
– Introduced SQL support since IMS V7 for Java application
– IMS V11 provided Open Database Solution allowing Java
applications to access IMS databases over TCP/IP networks
and off platform
– Supports both data access and data manipulation with SQL.
It maps hierarchical structures to relational concepts
UU45 | Dodge | Viper
PR27 | Dodge | Durango
53SJ9 | Mary | 111 Penny Lane
53SJ8 | Bob | 240 Elm St.
Dealer
Segment
Model
Segment
FF13 | Toyota | Camry
53SJ7 | George | 555 Bailey Ave.
Hierarchical Design Relational Design
DealerID DealerName DealerAddress
Dealer Table
ID Make Model Dealer
Model Table
UU45 Dodge Viper 53SJ7 0
PR27 Dodge Durango 53SJ7 0
FF13 Toyota Camry 53SJ7 0
JR27 Dodge Durango 53SJ8 1
WJ45 Mercury Cougar 53SJ8 1
... ... ... ... ...
0 53SJ7 George 555 Bailey Ave.
1 53SJ8 Bob 240 Elm St.
2 53SJ9 Mary 111 Penny Ln.
... ... ... ...
JPR27 | Dodge | Durango
WJ45 | Mercury | Cougar
Row 1 -
Row N -
Row 1 -
Row N - Segment 1
(Row 1) -
Hierarchical to Relational Mapping
• Relational databases versus IMS databases
– Table (relational DB) Segment (IMS DB)
– Column Field
– Row Segment Instance
– Schema PCB
– Table primary key Segment unique key
• Basic definitions
– Statement - standardized set of commands used for data
access, manipulation. Similar to executing a series of DL/I
calls against a DB PCB.
– Result Set – statements return a set of results based on the
command executed. Similar to the IO Area returned on a DL/I
call.
Other Terminologies
IMS Catalog
• Trusted, comprehensive view of IMS database metadata (including application metadata) managed by IMS
– PSB, DBD and copybooks
• SQL support for COBOL directly access IMS Catalog for database metadata
– No need to generate metadata for use in applications
ACBLIB
Catalog
PSB
source PSBLIB
DBD
source DBDLIB
PSBGEN
DBDGEN
ACBGEN IMS Explorer
IMS ACBLIB
Catalog
PSB
source PSBLIB
DBD
source DBDLIB
PSBGEN
DBDGEN
ACBGEN IMS Explorer
IMS ACBLIB
Catalog
PSB
source PSBLIB
DBD
source DBDLIB
PSBGEN
DBDGEN
ACBGEN IMS Explorer
IMS ACBLIB
Catalog
PSB
source PSBLIB
DBD
source DBDLIB
PSBGEN
DBDGEN
ACBGEN IMS Explorer
IMS ACBLIB ACBLIB
ACBGEN
ACBLIB PSBLIB
ACBGEN
ACBLIB
PSB
source PSBLIB
ACBGEN
ACBLIB
Catalog
IMS Explorer
IMS
Catalog
IMS Explorer
IMS 13 SQL support for COBOL
Statements – SQL to access data
• Data manipulation
– SELECT… FROM… to retrieve data
– INSERT INTO… VALUES… to insert data
– UPDATE… SET… to update data
– DELETE FROM… to delete data
– WHERE… AND… OR… to perform conditional selection of
data
Statements – Declaration
• Pre-compiler directives
– DECLARE CURSOR, STATEMENT… to declare cursor,
statement
– INCLUDE SQLIMSCA, SQLIMSDA… to generate SQLIMSCA
and SQLIMSDA structures
– WHENEVER… to handle errors and warnings
Statements – Execution
• SQL statement execution
– For executing a SELECT statement
• PREPARE … to parse SQL statement
• DESCRIBE (optional)… to get resultset metadata
• OPEN … to open cursor
• FETCH … to fetch data
• CLOSE … to close cursor processing
– For executing an INSERT/UPDATE/DELETE statement
• PREPARE… to parse SQL statement
• EXECUTE… to execute the non-SELECT statement
• Delimit SQL statement using EXEC SQLIMS ... END-EXEC
• Dynamic SQL programming model
– Must call PREPARE to process SQL statement
• Host variables
– Use for both to send and receive data processed by IMS
• SQL communication area (SQLIMSCA)
– Structure used by IMS to provide status feedback
– SQLIMSCODE (error code), SQLIMSSTATE (state), SQLIMSERRM
(error message)
• SQL description area (SQLIMSDA)
– Structure populated by IMS to provide result set metadata for a SELECT
statement
• Describe name, length, type of each column returned
– Structure populated by application to provide input data
Solution Details – Key application elements
• Enable SQL statement to be constructed at runtime
– No need to hard code SQL statement in the application
– Segment and field names associated with the SQL calls are
not known at compile time
– SQL accepts as input in the form of a character string
• Use Prepare call to process SQL statement
– Parse SQL statement for syntax and semantics validation at
runtime. No bind process.
– Convert SQL artifacts to DLI
– Statement can be prepared once and then execute many
times
Solution Details – Dynamic SQL
Coding - High-level application flow
Declare host variable/structures for passing data between
IMS and application
Include SQLIMSCA for execution status
Code SELECT, INSERT, UPDATE or DELETE
statements to access IMS data
Check SQLIMSCA for execution status
Handle any SQL errors returned by IMS
Coding - SELECT
• SELECT statements are used to query one or more tables
– SELECT column1, column2, … FROM table_name WHERE
some_column=some_value ORDER BY column1, column2
• Programming models
– PREPARE… OPEN… FETCH (one or more)… CLOSE
– Fixed-list SELECT
• Returns rows that contain a known number of values of unknown type and size.
You can specify a list of host variables to contains the filled values.
– Varying-list SELECT
• Returns rows that contain an unknown number of values of unknown type and size.
You do not know the exact number and types of host variables to store the result
values.
1. Include SQLIMSCA
2. Specify SQL statement in a COBOL variable
3. Declare host variable or structure for result data row
4. Declare a cursor for the statement name
5. Prepare the SELECT statement
6. Open the cursor
7. Fetch a row of data into host variable or structure.
8. Repeat previous step until not more data
When no more data, SQLIMSCODE=100
9. Handle any error
10.Close the cursor
Coding Fixed-list SELECT
Sample COBOL SQL
WORKING-STORAGE SECTION.
* Declare SQLIMSCA
EXEC SQLIMS INCLUDE SQLIMSCA END-EXEC.
* Declare COBOL variable for SQL statement and result data
01 SQL-STATEMENT
49 SQL-STATEMENT-LEN PIC S9(4) COMP.
49 SQL-STATEMENT-TEXT PIC X(100).
01 HOSPITAL-RESULT-ROW
05 HOSPLL PIC S9(3) BINARY.
05 HOSPCODE PIC X(12).
05 HOSPNAME PIC X(17).
PROCEDURE DIVISION.
* Declare Cursor for the Prepared Statement
EXEC SQLIMS
DECLARE CURSOR cursor-name for prepared-statement-name
END-EXEC.
* Load SQL statement in the COBOL variable
MOVE "SELECT * FROM PCB01.HOSPITAL” TO SELECT-STATEMENT-TXT.
* Prepared SQL statement string for processing
EXEC SQLIMS
PREPARE prepared-statement-name FROM :SQL-STATEMENT
END-EXEC.
* Open Cursor
EXEC SQLIMS
OPEN cursor-name
END-EXEC.
* Execute SQL statement
* Fetch data from IMS into host variable until no more data is found
PERFORM FETCH-PROC
UNTIL SQLCODE EQUAL 100.
:
FETCH-PROC.
EXEC SQLIMS
FETCH cursor-name INTO :HOSPITAL-RESULT-ROW
END-EXEC.
:
* Close Cursor
EXEC SQLIMS
CLOSE cursor-name
END-EXEC.
Sample COBOL SQL (Cont’d)
Coding Varying-list SELECT 1. Include SQLIMSCA
2. Include SQLIMSDA for result metadata
3. Specify SQL statement in a COBOL variable
4. Declare a cursor for the statement name
5. Prepare the SELECT statement
6. Call DESCRIBE to get result metadata
7. Declare and allocate storage for the result data variables
8. Open the cursor
9. Fetch a row of data into SQLIMSDA with result data variables
10. Repeat previous step until not more data
When no more data, SQLIMSCODE=100
11. Handle any error
12. Close the cursor
SQL descriptor area (SQLIMSDA)
• SQLIMSDA stores information about prepared SQL
statements or host variables.
• Can be read by IMS or the application
– Read by application after a DESCRIBE statement for result
set metadata
– Read by IMS for the input host variables
Coding – INSERT/UPDATE/DELETE
• INSERT
– INSERT INTO table_name (column1, column2, column3,...)
VALUES (value1, value2, value3,...)
• UPDATE
– UPDATE table_name SET column1=value,
column2=value2,... WHERE some_column=some_value
• DELETE
– DELETE FROM table_name WHERE
some_column=some_value
• Programming model
– PREPARE… EXECUTE
1. Include SQLIMSCA
2. Specify SQL statement in a COBOL variable
3. Declare host variable or structure for result data row
4. Declare a cursor for the statement name
5. Prepare the INSERT/UPDATE/DELETE statement
6. Execute the statement
7. Handle any error
Check if SQLIMSCODE = 0
Coding INSERT/UPDATE/DELETE
• A parameter marker is a question mark (?) that represents a
position in a dynamic SQL statement where the application
will provide a value
– SELECT HOSPNAME FROM PCB01.HOSPITAL WHERE
HOSPCODE = ?
– INSERT INTO PCB01.HOSPITAL (HOSPCODE,
HOSPNAME) VALUE (?, ?)
• Programming Model
– For SELECT statement, use USING clause with OPEN cursor
• e.g. OPEN cursor USING :value1
– For non-SELECT statement, use USING clause with
EXECUTE
• e.g. EXECUTE stmt USING :value1, :value2
Coding – Parameter markers
Handling errors
• SQL communication area (SQLIMSCA)
– Structure used by the database to provide status feedback
– The SQL INCLUDE statement is used in the COBOL
application to provide the declaration of the SQLIMSCA
• The main elements in the SQLIMSCA are:
– SQLIMSCODE – A return code represents a successful or
failed SQL operation
– SQLIMSSTATE – Common codes for error conditions which
conform to the SQL standard
– SQLIMSERRM – Error message text
Handling errors (cont’d)
• The SQLIMSCODE is a return code for a successful or failed SQL operation.
– If SQLIMSCODE = 0 and SQLWARN0 is blank, execution was successful.
– If SQLIMSCODE = 100, "no data" was found.
– If SQLIMSCODE > 0 and not = 100, execution was successful with a warning.
– If SQLIMSCODE = 0 and SQLWARN0 = 'W', execution was successful with a warning.
– If SQLIMSCODE < 0, execution was not successful.
• IMS DL/I Status Codes will be shown in message text in some error cases
IMS COBOL application
source files with SQL
statements
Libraries Object files
COBOL Link
Executable Program
COBOL Compiler with
IMS coprocessor Translate
EXEC SQLIMS
INCLUDE
DFSLI000
Compile and link
IMS coprocessor
• Compile IMS SQL COBOL application with IMS coprocessor
• Pre-process EXEC SQLIMS statements in COBOL source
• Integrated with Enterprise COBOL V5.1
• Specify ‘SQLIMS’ compiler option to compile COBOL
program with IMS SQL calls
//**********************************
//* COMPILING IMS COBOL SQL PROGRAM
//**********************************
//COBOL1 EXEC PGM=IGYCRCTL,
// PARM='LIST,XREF,CP(37),SQLIMS("APOSTSQL"),DUMP,LIB,DYNAM'
//STEPLIB DD DSN=IGYV5R10.TRIAL.SIGYCOMP,DISP=SHR
// DD DSN=IGYV5R10.TRIAL.SIGYMAC,DISP=SHR
// DD DSN=IMSBLD.IMSTS%%.CRESLIB,DISP=SHR
//SYSLIB DD DSN=IGYV5R10.TRIAL.CEEZ1D0.SCEERUN,DISP=SHR
// DD DSN=USER.PRIVATE.PROCLIB,DISP=SHR
//SYSPRINT DD SYSOUT=A
//SYSLIN DD DSN=&&LOADSET,DISP=(MOD,PASS),
// UNIT=SYSDA,SPACE=(80,(500,200))
Sample JCL for compile
Considerations
• The IMS catalog must be enabled and loaded with the database
metadata needed by the COBOL SQL application.
• Batch and DB Batch, CICS and DB2 SP are not supported for IMS
COBOL SQL access.
• Specify at least 12M for your IMS dependent region size for
running a COBOL SQL application.
• SQL Keywords and API
– Not all IMS JDBC SQL keywords are currently supported for COBOL
applications. For example, aggregate functions and XML are not
supported
– COBOL SQL supports keywords used for database access calls only
– SQL COMMIT and ROLLBACK keywords are not supported. Use IMS
DB system services call to commit or roll back your database changes
– Only one cursor and SQL statement can be active at a time
– Only EBCDIC CCSID 37 and 1140 codepages for the COBOL
CODEPAGE option are supported.
– Always fully qualify all tables (segments) and columns (fields) in SQL
statements. Specify the schema (PCB) name – e.g. PCB01.HOSPITAL
• For IMS database services, GSAM, IMS TM and Message processing services, continue to use DL/I API
Considerations (cont’d)
Documentation
• Application Programming Guide
– Programming for IMS -> Application programming ->
Application Programming for SQL
• Application Programming Reference
– Programming for IMS -> Application programming APIs ->
SQL programming reference
• Messages and Codes
– Troubleshooting for IMS -> IMS component codes -> SQL
codes
z/OS
IMS DB
DLI
SQL processor
Catalog
Metadata SQL
IMS
Co
nn
ect
DRDA
MPP BMP IFP COBOL
Lan
gu
ag
e
Inte
rface
IMS
JDBC
RYO
.NET
Op
en
Data
base M
an
ag
er
Language nterface
SQL ODBA / DRA Distributed
Intended support
Intended support
• Consolidated SQL processor for both host (COBOL) and
distributed applications (.NET/JDBC)
V13 support
Thank You
Your feedback is important!
