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OLE client

Question: Can an OPO application act as an OLE client and use OLE automation with an OLE server? Answer: OPO Version 2.0 can act as an OLE server, but not

Compound key

Question: I want to use a unique compound key, with a string columns and a numeric column, in my table. Since Blaze does not support compound keys, I will have

Repeater fields

Question: Whenever I try to reference an object in a repeater, I get an error message telling me that “Repeated control can be used only in aggregation function”. How can

Balnk form

Question: How do I open up a blank form – a form without any values displayed? Answer: As you probably know, you can add a DefaultCondition to your form, such

EXEC SQL and errors

Question: I am using the EXEC SQL command to insert some data into a database on the CommitForm()method of a form, but the data is not showing up in the

Set focus

Question: When a user selects a value from a list box, I populate the contents of arepeater. I also want to set the focus into the repeater’s first field.How can

Global functions

Question: How can I define a function that is not associated with a particular form? Answer: You can define an function that is not associated with a particular form by

Formatting data

Question: When I set the FormatMask property for a data field object, the value of the field is formatted when a user enters data and tabs out of the field.

Enumerating instances

Question: I want to use many instances of a class in my form, but can’t seem to figure out an easy way to check on the status of all the


Question: Is there a way to send mail with a mouse click? I’m working on a Mac and in Windows. Answer: You can send mail, or do virtually anything else

Querying a List

Question: I’ve been trying to construct a query on the databaseto see if the value in a particular field matches a long list of correct answers. For example, I would

Adjusting for Deleted Rows

Question: How do I create a column with a row ID that adjusts if a row is deleted?That is, if I had numbers 1,2,3,4,5,6 and I delete record 3, record

Splitting Data Within a Column

Question: I am trying to write a report that will bring back fiveindividual pieces of data that are stored within the same column in a table. How do I do

COUNT Function: Getting a Series

Question: What is the syntax to get a series of “counts” on a table? An exampleof what I am trying to do is as follows:SELECT col1 = COUNT(tstfield1=’X’),col2 = COUNT(tstfield2=’Y’)

Join Performance

Question: I’m wondering whether it would be faster to join a large table to a small table by placing the large table on the left side or theright side of

UPDATE Table Based on Data in Another Table

Question: I have two related tables. I need to go and update atable searching for a value I find in the second table (byjoining both tables). I wrote the following

SQL parsing error

Question: I have been having a lot of trouble with a SqlLookup() function. Whenever I use a WHERE clause, I get a parse error.The offending WHERE clause is “WHERE SW_LICENSE

How are transactions handled in OPO?

Question: How are transactions handled in OPO? Answer: Transactions are the core of multi-user data processing integrity. A transaction defines an all-or-none unit of work. The classic example of a

Column lengths

Question: Data field objects in OPO can accept any amount of data, but if I send too many characters to the server, I get an error “flushing the row to

Normalized Database: When to Split?

Question: We have several heavily-used tables with lots of columns (average around 30 columns), and the users are getting locked out frequently. We’ve thought about splitting the tables, but didn’t

Lock Conflicts

Question: Our system is experiencing several lock conflicts. We’ve got a consultantlooking at the details, but I was hoping you could explain what’s going onbehind the scenes when records are

Differences Between Join Types

Question: What are the differences between LEFT, RIGHT, INNER and OUTER JOINS? Answer: An INNER JOIN is the most common type: It combines all the data from the tables specified

Data Replication as a WAN Solution

Question: I have nine offices. I want each office to connect across aWAN and run client/server applications with all datacontained on one central server. However, we are finding the delays

BLOB Data Storage

Question: What are the advantages/disadvantages of putting large binary files (1+ MB) in BLOB columns versus storing them on a file server with a reference such as a directory/file spec

Checking for a lost connection

Question: I want to periodically check to see if a user’s database connection has been lost. How can I? Answer: First of all, a solution. You can implement periodic ‘polling’

Improving performance

Question: The repeater in my application seems to be very slow in populating. Is there anything I can do to improve its performance? Answer: Poor performance can be the result

Data Replication

Question: I’ve heard several of the arguments in favor of a server that supports datareplication. What are the potential problems? Answer: For our readers, the advantages of data replication [creating

repaint() and Consecutive Lines

Question: My applet draws lines. I click at the place where I want my line to start and then I click at the end of it. It draws a line

How can I get the display value of a list box?

Question: How can I get the display value of a list box? Answer: In Oracle Power Objects, the Value property of the list box isautomatically set to the internal value

An Introduction to Mono Development

any .NET developers, accustomed to Microsoft’s Windows-only development tools’ capabilities, are quite surprised when they learn that .NET is platform-independent. But it’s true. You can

High-Noon Showdown at Render Gulch

odern computer hardware and powerful graphics cards, now found in even ‘budget’ systems, support a new level of rapid rendering of more high-level descriptions of

Unit Test Secured EJBs in Production

nit testing, a critical part of the software development process, involves individually testing each unit of code to make sure that it works correctly on

Creating a StAX Filter for XML

This tip creates a StAX filter using the interface. This filter accepts only characters, but you can also set the filter XML to retrieve

WCF Essentials—A Developer’s Primer

indows Communication Foundation (WCF) provides a runtime environment for your services, enabling you to expose CLR types as services and to consume services as CLR