try
open database southwind
catch
die("Cannot open database, please try later.")
endtry
In this article Barry Mavin, CEO and Chief Software Architect for Recital, gives details on Working with user-defined Functions in the Recital Database Server.
Overview
User-defined functions (UDFs) are collections of statements written in the Recital 4GL (compatible with Visual FoxPro) stored under a name and saved in a Database. User-defined functions are just-in-time compiled by the Recital database engine. User-defined functions can be used in SQL statements to extend the power and flexibility of the inbuilt functions. Using the Database Administrator in Recital Enterprise Studio, you can easily create, view, modify, and test Stored Procedures, Triggers, and user-defined functions.
Tip
You can also extend the Recital Database Server with C Extension Libraries and use the functions defined within that library also.Creating and Editing user-defined functions
To create a new User-defined function, right-click the Procedures node in the Databases tree of the Project Explorer and choose Create. To modify an existing User-defined function select the User-defined function in the Databases Tree in the Project Explorer by double-clicking on it or selecting Modify from the context menu. By convertion we recommend that you name your User-defined functions beginning with "f_xxx_", where xxx is the name of the table that they are associated with.
Testing the user-defined function
To test run the user-defined function, select it in the Databases Tree in the Project Explorer by double-clicking on it. Once the Database Administrator is displayed, click the Run button to run it.
Example
Example: user-defined function "f_order_details_total".
////////////////////////////////////////////////////////////////////////
// example user-defined function
function f_order_details_total(pUnitprice, pQuantity, pDiscount)
return (pUnitprice + pQuantity + pDiscount) > 0
endfunc
Example: using the user-defined function in a SQL SELECT statement.
//////////////////////////////////////////////////////////////////////// // sample code to use a user-defined function in a SQL SELECT statement select * from customers where f_order_details_total(Unitprice, Quantity, Discount)
Using user-defined function libraries with the Recital Database Server
You can place all of the user-defined functions associated with a particular table into a procedure library. You then define an Open Trigger for the table that opens up the procedure library whenever the table is accessed. This is a much faster way of using user-defined functions as it reduces the amount of file open/close operations during a query and also simplifies development and maintenance.
By convertion we recommend that you should name the library using the convention "lib_xxx", where xxx is the name of the table that the library is associated with.
Example: procedure library in lib_order_details.
////////////////////////////////////////////////////////////////////////
// example user-defined functions
function f_order_details_total(pUnitprice, pQuantity, pDiscount)
return (pUnitprice * pQuantity - pDiscount) > 0
endfunc
function f_order_details_diff(pUnitprice, pQuantity, pDiscount, pValue)
return f_order_details_total(pUnitprice, pQuantity, pDiscount) - pValue
endfunc
Example: Open Trigger in dt_order_details_open.
//////////////////////////////////////////////////////////////////////// // This trigger will open up the procedure library when the table is opened set procedure to lib_order_details additive
Example: Close Trigger in dt_order_details_close.
//////////////////////////////////////////////////////////////////////// // This trigger will close the procedure library when the table is closed close procedure lib_order_details
Example: using the user-defined function in a SQL SELECT statement.
//////////////////////////////////////////////////////////////////////// // sample code to use a user-defined function in a SQL SELECT statement select * from customers where f_order_details_total(Unitprice, Quantity, Discount)
User-defined functions can also be used with any of the Client Drivers that work with the Recital Database Server.
If you have 4 GB or more RAM use the Linux kernel compiled for PAE capable machines. Your machine may not show up total 4GB ram. All you have to do is install PAE kernel package.
This package includes a version of the Linux kernel with support for up to 64GB of high memory. It requires a CPU with Physical Address Extensions (PAE).
The non-PAE kernel can only address up to 4GB of memory. Install the kernel-PAE package if your machine has more than 4GB of memory (>=4GB).
# yum install kernel-PAE
If you want to know how much memory centos is using type this in a terminal:
# cat /proc/meminfo
Some options of hdparm are dangerous and are generally listed as such in the man page.
Hdparm is available from SourceForge and there is even a version for Windows.
// declare some simple procedures
proc display(cArg)
echo "display=" + cArg
endproc
proc show(cArg)
echo "show=" + cArg
endproc
// create an object based on an anonymous class
myobj = new object()
// add some properties
myobj["name"] = "barry"
myobj["company"] = "recital"
// now declare an anonymous method
myobj["mymethod"] = display
// call the method
myobj.mymethod("hello world") // displays "display=hello world"
// redeclare the method
myobj["mymethod"] = show
// call the method
myobj.mymethod("hello world") // displays "show=hello world"
Where this becomes particularly useful is when you have a procedure that calls anonymous methods in order to process data. This technique can be used to call anonymous procedures in your code.
proc processdata(oArg)
oArg.mymethod(oArg.name)
endproc
proc show(cArg)
echo "show=" + cArg
endproc
myobj = new object()
myobj["name"] = "barry"
myobj["mymethod"] = show
processdata(myobj) // displays "show=barry" USE accounts INDEX on account_no TAG outstanding FOR balance > 0 EXPLAIN SELECT * FROM accounts WHERE balance > 0 Optimized using for condition on tag 'OUTSTANDING'
- edit the .vmx file and add the following line
uuid.action = "keep"
- set the virtual machine to power off when vmware is stopped. Do not set this to "suspend" or it will not restart on the backup machine.
./configure CFLAGS='-arch x86_64' APXSLDFLAGS='-arch x86_64' --with-apxs=/usr/sbin/apxsThen you must pass the these additional flags to the apxs command in order to generate a Universal Binary shared module.
-Wl,-dynamic -Wl,'-arch ppc' -Wl,'-arch ppc64' -Wl,'-arch i386' -Wl,'-arch x86_64' -Wc,-dynamic -Wc,'-arch ppc' -Wc,'-arch ppc64' -Wc,'-arch i386' -Wc,'-arch x86_64'If you then do a file command on the shared module it should return;
$ file mod_recital.so mod_recital2.2.so: Mach-O universal binary with 4 architectures mod_recital2.2.so (for architecture ppc7400): Mach-O bundle ppc mod_recital2.2.so (for architecture ppc64): Mach-O 64-bit bundle ppc64 mod_recital2.2.so (for architecture i386): Mach-O bundle i386 mod_recital2.2.so (for architecture x86_64): Mach-O 64-bit bundle x86_64The apache module files are stored in the /usr/libexec/apache2/ directory on a default apache install on the Mac and the configuration file is /private/etc/apache2/httpd.conf
# recital < mrprog.prgIndividual commands can be executed in shell scripts.
# recital < myprog.prg > myoutput.txt
# recital > myoutput.txt <<END
use customers
list structure
END
# echo "select * from sales!customers where overdue" | recital | wc -l
# recital -c "create database sales"Expressions can be evaluated and used in shell scripts.
# recital -c "create table sales!invoices (id int, name char(25), due date)"
# VER=`recital -e "version(1)"`You can view what command line options are available by typing:
# recital --help