IBM Books

Application Building Guide


IBM C Set++

This section contains the following topics:

DB2 API Applications

The script file bldcsetapi in sqllib/samples/c contains the commands to build a DB2 API program. The one parameter it takes, $1, specifies the name of your source file.



#! /bin/ksh
# bldcsetapi script file
# Builds a C++ DB2 API program that does not contain embedded SQL.
# Usage: bldcsetapi <prog_name>
 
# Set DB2PATH to where DB2 will be accessed. 
# The default is the standard instance path.
DB2PATH=$HOME/sqllib
 
# Compile the util.C error-checking utility.
xlC -I$DB2PATH/include -c util.C
# Compile the program.
xlC -I$DB2PATH/include -c $1.C
# Link the program.
xlC -o $1 $1.o util.o -ldb2 -L$DB2PATH/lib


Compile and Link Options for bldcsetapi

The script file contains the following compile options:

xlC
The IBM C Set ++ compiler.

-I$DB2PATH/include
Specify the location of the DB2 include files. For example: $HOME/sqllib/include.

-c
Perform compile only; no link. This book assumes that compile and link are separate steps.

The script file contains the following link options:

xlC
Use the compiler as a front end for the linker.

-o $1
Specify the executable program.

-o $1
Specify the program object file.

util.o
Include the utility object file for error checking.

-ldb2
Link with the database manager library.

-L$DB2PATH/lib
Specify the location of the DB2 runtime shared libraries. For example: $HOME/sqllib/lib. If you do not specify the -L option, the compiler assumes the following path /usr/lib:/lib.

Refer to your compiler documentation for additional compiler options.

To build the sample program client from the source file client.C , enter:

   bldcsetapi client

The result is an executable file, client. You can run the executable file against the sample database by entering:

   client

Embedded SQL Applications

The script file bldcset, in sqllib/samples/cpp, contains the commands to build an embedded SQL program.

The first parameter, $1, specifies the name of your source file. The second parameter, $2, specifies the name of the database to which you want to connect. Parameter $3 specifies the user ID for the database, and $4 specifies the password. Only the first parameter, the source file name, is required. Database name, user ID, and password are optional. If no database name is supplied, the program uses the default sample database.

#! /bin/ksh
# bldcset script file
# Build sample C++ program that contains embedded SQL.
# Usage: bldcset <prog_name> [ <db_name> [ <userid> <password> ]]
 
# Set DB2PATH to where DB2 will be accessed. 
# The default is the standard instance path.
DB2PATH=$HOME/sqllib
 
# Connect to a database.
if (($# < 2))
then
   db2 connect to sample
elif (($# < 3))
then
   db2 connect to $2
else
   db2 connect to $2 user $3 using $4
fi
 
# Precompile the program.
db2 prep $1.sqC bindfile
 
# Bind the program to the database.
db2 bind $1.bnd
 
# Disconnect from the database.
db2 connect reset
 
# Compile the util.c error-checking utility.
xlC -I$DB2PATH/include -c util.C
 
# Compile the program.
xlC -I$DB2PATH/include -c $1.C
 
# Link the program.
xlC -o $1 $1.o util.o -ldb2 -L$DB2PATH/lib


Compile and Link Options for bldcset

The script file contains the following compile options:

xlC
The IBM C Set++ compiler.

-I$DB2PATH/include
Specify the location of the DB2 include files. For example: $HOME/sqllib/include.

-c
Perform compile only; no link. This book assumes that compile and link are separate steps.

The script file contains the following link options:

xlC
Use the compiler as a front end for the linker.

-o $1
Specify the executable program.

$1.o
Specify the program object file.

util.o
Include the utility object file for error checking.

-ldb2
Link with the database manager library.

-L$DB2PATH/lib
Specify the location of the DB2 runtime shared libraries. For example: $HOME/sqllib/lib. If you do not specify the -L option, the compiler assumes the following path: /usr/lib:/lib.

Refer to your compiler documentation for additional compiler options.

To build the sample program updat from the source file updat.sqC , enter:

   bldcset updat

The result is an executable file updat. You can run the executable file against the sample database by entering the executable name:

   updat

Embedded SQL Stored Procedures

Note:Please see the information for building C++ stored procedures and UDFs in "C++ Considerations for UDFs and Stored Procedures".

The script file bldcsetsrv, in sqllib/samples/cpp, contains the commands to build a stored procedure. The script file compiles the stored procedure into a shared library that can be called by a client application.

The first parameter, $1, specifies the name of your source file. The second parameter, $2, specifies the name of the database to which you want to connect. Parameter $3 specifies the user ID for the database, and $4 specifies the password. Only the first parameter, the source file name, is required. Database name, user ID, and password are optional. If no database name is supplied, the program uses the default sample database.

The script file uses the source file name, $1, for the shared library name.

#! /bin/ksh
# bldcsetsrv script file
# Builds a C++ stored procedure.
# Usage:
# bldcsetsrv <stor_proc_name> [ <db_name> [ <userid> <password> ]]
 
# Set DB2PATH to where DB2 will be accessed. 
# The default is the standard instance path. 
DB2PATH=$HOME/sqllib
 
# Connect to a database.
if (($# < 2))
then
   db2 connect to sample
elif (($# < 3))
then
   db2 connect to $2
else
   db2 connect to $2 user $3 using $4
fi
 
# Precompile the program.
db2 prep $1.sqC bindfile
# Bind the program to the database.
db2 bind $1.bnd                    
# Disconnect from the database.    
db2 connect reset
 
# Compile the program.
xlC -I$DB2PATH/include -c $1.C
 
# Link the program using the export file $1.exp,
# creating a shared library called $1 
makeC++SharedLib -p 1024 -o $1 $1.o -L$DB2PATH/lib -ldb2 -E $1.exp
 
# Copy the shared library to the DB2 instance sqllib/function subdirectory. 
# Note: this assumes the user has write permission to this directory.
rm -f $DB2PATH/function/$1
cp $1 $DB2PATH/function 


Compile and Link Options for bldcsetsrv

The script file contains the following compile options:

xlC
The IBM C Set++ compiler.

-I$DB2PATH/include
Specify the location of the DB2 include files. For example: $HOME/sqllib/include.

-c
Perform compile only; no link. This book assumes that compile and link are separate steps.

The script file contains the following link options:

makeC++SharedLib
Linker script for stored procedures with static constructors.

-p 1024
Set the priority to the arbitrary value of 1024.

-o $1
Specify the output as a shared library file.

$1.o
Specify the program object file.

-L$DB2PATH/lib
Specify the location of the DB2 runtime shared libraries. For example: $HOME/sqllib/lib. If you do not specify the -L option, the compiler assumes the following path: /usr/lib:/lib.

-ldb2
Link with the database manager library.

-E $1.exp
Specify an export file. The export file contains a list of the stored procedures.

Refer to your compiler documentation for additional compiler options.

To build the sample program outsrv from the source file outsrv.sqC , enter:

   bldcsetsrv outsrv

The script file copies the stored procedure to the server in the path sqllib/function. For DB2DARI parameter style stored procedures where the invoked procedure matches the shared library name, this location indicates that the stored procedure is fenced. If you want this type of stored procedure to be unfenced, you must move it to the sqllib/function/unfenced directory. For all other types of DB2 stored procedures, you indicate whether it is fenced or not fenced with the CREATE FUNCTION statement in the calling program. For a full discussion on creating and using the different types of DB2 stored procedures, please see the "Stored Procedures" chapter in the Application Development Guide.
Note:An unfenced stored procedure runs in the same address space as the database manager and results in increased performance when compared to a fenced stored procedure, which runs in an address space isolated from the database manager. With unfenced stored procedures there is a danger that user code could accidentally or maliciously damage the database control structures. Therefore, you should only run unfenced stored procedures when you need to maximize the performance benefits. Ensure these programs are thoroughly tested before running them as unfenced. Refer to the Application Development Guide for more information.

If necessary, set the file mode for the stored procedure so the DB2 instance can run it.

Once you build the stored procedure outsrv, you can build the client application outcli that calls the stored procedure. You can build outcli using the script file bldcset. Refer to "Embedded SQL Applications" for details.

To call the stored procedure, run the sample client application by entering:

   outcli remote_database userid password

where

remote_database
Is the name of the database to which you want to connect. The name could be sample, or its remote alias, or some other name.

userid
Is a valid user ID.

password
Is a valid password.

The client application passes a variable to the server program outsrv, which gives it a value and then returns the variable to the client application.

User-Defined Functions (UDFs)

Note:Please see the information for building C++ UDFs and stored procedures in "C++ Considerations for UDFs and Stored Procedures".

The script file bldxlCudf, in sqllib/samples/cpp, contains the commands to build a UDF. UDFs cannot contain embedded SQL statements. Therefore, to build a UDF program, you never need to connect to a database or precompile and bind the program.

The parameter, $1, specifies the name of your source file. The script file uses the source file name, $1, for the shared library name.



#! /bin/ksh
# bldxlCudf script file -- AIX
# Builds a sample C++ UDF library.
# Usage: bldxlCudf <prog_name>
 
# Set DB2PATH to where DB2 will be accessed. 
# The default is the standard instance path. 
DB2PATH=$HOME/sqllib
 
# Compile the program. The extension ".c" is for a C source file.
# Change the extension to ".C" if compiling a C++ source file.
xlC -I$DB2PATH/include -c $1.c
 
# Link the program.
makeC++SharedLib -p 1024  -o $1 $1.o -L$DB2PATH/lib -ldb2 -ldb2apie -E $1.exp 
 
# Copy the shared library to the sqllib/function subdirectory of the DB2 instance.
# Note: this assumes the user has write permission to this directory.
rm -f $DB2PATH/function/$1
cp $1 $DB2PATH/function


Compile and Link Options for bldxlCudf

The script file contains the following compile options:

xlC
The IBM C Set++ compiler.

-I$DB2PATH/include
Specify the location of the DB2 include files. For example: $HOME/sqllib/include.

-c
Perform compile only; no link. This book assumes that compile and link are separate steps.

The script file contains the following link options:

makeC++SharedLib
Linker script for stored procedures with static constructors.

-p 1024
Set the priority to the arbitrary value of 1024.

-o $1
Specify the output as a shared library file.

$1.o
Specify the program object file.

-L$DB2PATH/lib
Specify the location of the DB2 runtime shared libraries. For example: $HOME/sqllib/lib. If you do not specify the -L option, the compiler assumes the following path: /usr/lib:/lib.

-ldb2
Link with the database manager library.

-ldb2apie
Link with the DB2 API Engine library to allow the use of LOB locators.

-E $1.exp
Specify an export file. The export file contains a list of the stored procedures.

Refer to your compiler documentation for additional compiler options. Refer to "UDFs and the CREATE FUNCTION Statement" for more information on creating UDFs.

To build the user-defined function program udf from the source file udf.c , enter:

   bldxlCudf udf

The script file copies the UDF to the server in the path sqllib/function.
Note:If you wish to build a C++ UDF program that has a .C extension, you must modify the script file bldxlCudf to accept programs with this extension.

If necessary, set the file mode for the UDF so the DB2 instance can run it.

Once you build udf, you can build the client application, calludf, that calls it. You can build the calludf program from the calludf.sqC source file in sqllib/samples/cpp using the script file bldcset. Refer to "Embedded SQL Applications" for details.

To call the UDF, run the sample calling application by entering the executable name:

   calludf

The calling application calls functions from the udf library.

After you run the calling application, you can also invoke the UDF interactively using the command line processor like this:

   db2 "SELECT name, DOLLAR(salary), SAMP_MUL(DOLLAR(salary), FACTOR(1.2)) FROM staff"

You do not have to type the command line processor keywords in uppercase.

Multi-threaded Applications

C++ multi-threaded applications on AIX Version 4 need to be compiled and linked with the xlC_r compiler instead of the xlC compiler or, for C, with the xlc_r compiler instead of the xlc compiler. If you are using AIX 4.3 or later, use the xlC_r7 or xlc_r7 compiler. The _r versions pass -D_REENTRANT to the C preprocessor and -lpthreads to the linker, so it is not necessary to do this explicitly. Please see the /etc/xlC.cfg file for more information.

The script file bldxlCmt, in sqllib/samples/cpp, contains the commands to build an embedded SQL multi-threaded program. If you want to build a DB2 API multi-threaded program, comment out the connect, precompile, bind, and disconnect commands.

The first parameter, $1, specifies the name of your source file. The second parameter, $2, specifies the name of the database to which you want to connect. Parameter $3 specifies the user ID for the database, and $4 specifies the password. Only the first parameter, the source file name, is required. Database name, user ID, and password are optional. If no database name is supplied, the program uses the default sample database.

#! /bin/ksh 
# bldxlCmt script file -- AIX                                
# Builds a multi-threaded program containing embedded SQL
# with IBM C++.
# Usage: bldxlCmt <prog_name> [ <db_name> [ <userid> <password> ]]   
 
# Set DB2PATH to where DB2 will be accessed. 
# The default is the instance path. 
DB2PATH=$HOME/sqllib
 
# Connect to a database.
if (($# < 2))
then
  db2 connect to sample
elif (($# < 3))
then
   db2 connect to $2
else
   db2 connect to $2 user $3 using $4
fi
 
# Precompile the program.
db2 prep $1.sqC bindfile
# Bind the program to the database.
db2 bind $1.bnd                    
# Disconnect from the database.    
db2 connect reset
 
# Compile the util.C error-checking utility.
xlC_r -I$DB2PATH/include -c util.C
# Compile the program.                                 
xlC_r -I$DB2PATH/include -c $1.C               
# Link the program                                      
xlC_r -o $1 $1.o util.o -L$DB2PATH/lib -ldb2

Besides the xlC_r compiler, discussed above, the other compile and link options are the same as those used in the embedded SQL script file, bldxlC. For information on these options, see "Embedded SQL Applications".

To build the multi-threaded sample program, thdsrver, from the source file thdsrver.sqC , enter:

   bldxlCmt thdsrver

The result is an executable file, thdsrver. To run the executable file against the sample database, enter the executable name:

   thdsrver


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