#SQL

Hi,

My doubt is about the SQL Query in Caché:

I don't want to take all results from the table and orgainze them manually, for example: I have a table with 50 records, but I only want to select 10 records, being from tenth until the twentieth and this without knowing their IDs.

So, how can I do this, without losing performance, there is any way?

I have a class that has a list property, which contains a list of other objects, and I want to join against it in SQL.

Class Foo Extends %Persistent
{
Property MyBars As list Of Bar;
}

I have a property, Emails, that needs to contain a list of comma-delimited values, or "". Is there a benefit to making this property a list of %String, a Collection[list] (or however you do it), an array, or anything other than a simple %String type?

The newer dynamic SQL classes (%SQL.Statement and %StatementResult) perform better than %ResultSet, but I did not adopt them for some time because I had learned how to use %ResultSet. Finally, I made a cheat sheet, which I find useful when writing new code or rewriting old code. I thought other people might find it useful.

First, here is a somewhat more verbose adaptation of my cheat sheet:

Sometimes, it comes in very handy (especially for the EAV model) to use array properties in a class and be able to qickly search by their elements: both the key and the value.

Let’s take a look at a simple example:

Overview

Encryption of sensitive data becomes more and more important for applications. For example patient names, SSN, address-data or credit card-numbers etc..

Cache supports different flavors of encryption. Block-level database encryption and data-element encryption. The block-level database encryption protects an entire database. The decryption/encryption is done when a block is written/read to or from the database and has very little impact on the performance.

With data-element encryption only certain data-fields are encrypted. Fields that contain sensitive data like patient data or credit-card numbers. Data-element encryption is also useful if a re-encryption is required periodically. With data-element encryption it is the responsibility of the application to encrypt/decrypt the data.

Both encryption methods leverage the managed key encryption infrastructure of Caché.

The following article describes a sample use-case where data-element encryption is used to encrypt person data.

But what if you have hundreds of thousands of records with an encrypted datafield and you have the need to search that field? Decryption of the field-values prior to the search is not an option. What about indices?

This article describes a possible solution and develops step-by-step a small example how you can use SQL and indices to search encrypted fields.

Whenever I try to run a simple query on a production database table, I get a timeout 504 error. I'm using the SQL interface in Ensemble. One of the queries is a simple SELECT TOP 10. Even SELECT COUNT(*) gives a timeout.

I have tried to run the SQL Runtime Statistics, but this gives me a timeout as well.

Does anyone have an idea where I might look to find what is causing this?

Thanks in advance,

Best regards

Glenn van Bavel,

Last week, we announced the InterSystems IRIS Data Platform, our new and comprehensive platform for all your data endeavours, whether transactional, analytics or both. We've included many of the features our customers know and loved from Caché and Ensemble, but in this article we'll shed a little more light on one of the new capabilities of the platform: SQL Sharding, a powerful new feature in our scalability story.

Hi -

I'm creating a custom report in Health Insight via SQL and one of the requirements says that I must include patients who are >= 13 years old (which is easy) but I also need to include patients who WILL be 13 years old as of December 31st of current year that the report is ran in.

I see that there is an Age column and an AgeInMonths column in HSAA.Patient. and of course a DOB column. I'm wondering if it is possible to do this purely using SQL (and SQL functions) or if I will have to incorporate a COS function to achieve this requirement.

Any suggestions?

I try to find a function, which generates hash values of columns. In MS SQL Server I can use

select hashbytes('sha2_256', my_column) ...

to create hash values of my_column. Is it possible to use such things in Caché?

Thank you
André

Greetings,

I am working on the first of many triggers which will have identical code upon row insertion or update of a single column. According to the document I should be able to define a multiple-event trigger using Cache SQL/DDL.

Here is a link to the current CREATE TRIGGER documentation. Within the description section is the following paragraph:

Quotes (1NF/2NF/3NF)^ru:

Every row-and-column intersection contains exactly one value from the applicable domain (and nothing else).
The same value can be atomic or non-atomic depending on the purpose of this value. For example, “4286” can be

• atomic, if its denotes “a credit card’s PIN code” (if it’s broken down or reshuffled, it is of no use any longer)
• non-atomic, if it’s just a “sequence of numbers” (the value still makes sense if broken down into several parts or reshuffled)

This article explores the standard methods of increasing the performance of SQL queries involving the following types of fields: string, date, simple list (in the $LB format), "list of <...>" and "array of <...>".

select * from A left join B on A.x = B.x inner join C on B.y = C.y

does Cache SQL treat the join path: LEFT_JOIN(A,INNER_JOIN(B.C)) also a valid candidate path?

Thanks.

Atelier Users:

Has anyone found an Eclipse plug-in that provides the capability to connect to a Caché server and give the user a way to write SQL queries using the tables from that server? I'm picturing something like a "WinSQL"-client built as an Eclipse plugin.

I've found and tried the following, but I couldn't get it to connect to my local Caché instance.

http://eclipsesql.sourceforge.net/