I'm converting some legacy embedded-Ingres C code to work against Oracle. I've found references to functions "inquire_ingres()" and "inquire_sql()," which, per the docs at http://docs.ingres.com/ingres/9.3/sql-reference-guide/2275-inquiresql-function, allow a program to gather runtime information about the status and results of the last SQL statement that the program issued.
Does Oracle provide similar convenience functionality, or am I going to have to just paw around some more in the innards of sqlca as I suspect I'm going to?
It looks like the answer is: you have to paw around in the innards of sqlca. There's a lot of good information buried in that struct though -- check out http://infolab.stanford.edu/~ullman/fcdb/oracle/or-proc.html#sqlca for some details.
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I am struggling to understand why the CommandId (documented here) is necessary in PostgreSQL. The CommandId is sometimes also called cmin and cmax.
I understand that the Transaction ID (xmin/xmax) is necessary. However the cmin/cmax values are documented to only be relevant for the current transaction.
I have been looking around pretty much everywhere, but even the .c/.h files in the PostgreSQL code base do not talk about it a lot.
I wonder if the C-Functions OCIExtractToInt and other OCIExtractToXXX provided by OCI could be used to extract data from statements? And if so how this could work? Sadly I could not find any example where something like this is done. Additionally the Oracle documentation does not help much at this point.
After doing some research, I was amazed with the power of Prolog to express queries in a very simple way, almost like telling the machine verbally what to do. This happened because I've become really bored with Propel and PHP at work.
So, I've been wondering if there is a way to translate database table rows (Postgres, for example) into Prolog facts. That way, I could stop using so many boring joins and using ORM, and instead write something like this to get what I want:
mantenedora_ies(ID_MANTENEDORA, ID_IES) :-
papel_pessoa(ID_PAPEL_MANTENEDORA, ID_MANTENEDORA, 1),
papel_pessoa(ID_PAPEL_IES, ID_IES, 6),
relacionamento_pessoa(_, ID_PAPEL_IES, ID_PAPEL_MANTENEDORA, 3).
To see why I've become bored, look at this post. The code there would be replaced for these simple lines ahead, much easier to read and understand. I'm just curious about that, since it will be impossible to replace things around here.
It would also be cool if something like that was possible to be done in PHP. Does anyone know something like that?
check the ODBC interface of swi-prolog (maybe there is something equivalent for other prolog implementations too)
http://www.swi-prolog.org/pldoc/doc_for?object=section%280,%270%27,swi%28%27/doc/packages/odbc.html%27%29%29
I can think of a few approaches to this -
On initialization, call a method that performs a selects all data from a table and asserts it into the db. Do this for each db. You will need to declare the shape of each row as :- dynamic ies_row/4 etc
You could modify load_files by overriding user:prolog_load_files. From this activity you could so something similar to #1. This has the benefit of looking like a load_files call. http://www.swi-prolog.org/pldoc/man?predicate=prolog_load_file%2F2 ... This documentation mentions library(http_load), but I cannot find this anywhere (I was interested in this recently)!
There is the Draxler Prolog to SQL compiler, that translates some pattern (like the conjunction you wrote) into the more verbose SQL joins. You can find in the related post (prolog to SQL converter) more info.
But beware that Prolog has its weakness too, especially regarding aggregates. Without a library, getting sums, counts and the like is not very easy. And such libraries aren't so common, and easy to use.
I think you could try to specialize the PHP DB interface for equijoins, using the builtin features that allows to shorten the query text (when this results in more readable code). Working in SWI-Prolog / ODBC, where (like in PHP) you need to compose SQL, I effettively found myself working that way, to handle something very similar to what you have shown in the other post.
Another approach I found useful: I wrote a parser for the subset of SQL used by MySQL backup interface (PHPMyAdmin, really). So routinely I dump locally my CMS' DB, load it memory, apply whathever duty task I need, computing and writing (or applying) the insert/update/delete statements, then upload these. This can be done due to the limited size of the DB, that fits in memory. I've developed and now I'm mantaining this small e-commerce with this naive approach.
Writing Prolog from PHP should be not too much difficult: I'd try to modify an existing interface, like the awesome Adminer, that already offers a choice among basic serialization formats.
Apologies for the fuzzy title...
My problem is this; I have a SQL Server table persons with about 100.000 records. Every person has an address, something like "Nieuwe Prinsengracht 12 - III". The customer now wants to separate the street from the number and addition (so each address becomes two or three fields). The problem is that we can not be sure of the format the current address is in, it could also simply be something like "Velperweg 30".
The only thing we do know about it is that it's a piece of text, followed by a number, possibly followed by some more text (which can contain a number).
A possible solution would be to do this with regexes, but I would much (much, much) rather do this using a query. Is there any way to use regexes in a query? Or do you have any other suggestions how to solve such a problem?
Something like this maybe?
SELECT
substring([address_field], 1, patindex('%[1-9]%', [address_field])-1) as [STREET],
substring([address_field], patindex('%[1-9]%', [address_field]), len([address_field])) as [NUMBER_ADDITON]
FROM
[table]
It relies on the assumption that the [street] field will not contain any numbers, and the [number_addition] field will begin with a number.
SQL Server and T-SQL are rather limited in their processing prowess - if you're really serious about heavy-lifting and regexes etc., you're best bet is probably creating an assembly in C# or VB.NET that does all that tricky Regex business, and then deploying that into SQL-CLR and use the functions in T-SQL.
"Pure" T-SQL cannot really handle much string manipulation beyond SUBSTRING and CHARINDEX - but that's about it.
In answer to your "Is there any way to use regexes in a query?", then yes there is, but it needs a little .NET knowledge. Create a CLR assembly with a user-defined function that does your regex work. Visual Studio 2008 has a template project for this. Deploy it to your SQL server and call it from your query.
Name and Address parsing and standardization is probably one of the most difficult problems we can encounter as programmers for precisely the reasons you've mentioned.
I assume that whoever you work for their main business is not address parsing. My advice is to buy a solution rather than build one of your own.
I am familiar with this company. Your address examples appear to be non US or Canadian so I don't know if their products would be useful, but they may be able to point you to another vendor.
Other than a user of their products I am not affiliated with them in any way.
This sounds like the common "take a piece of complex text that could look like anything and make it look like what we now want it to look like" problem. These tend to be very hard to do using only T-SQL (which does not have native regex functionality). You will probably have to work with complex code outside of the database to solve this problem.
TGnat is correct. Address standardization is complicated.
I've encountered this problem before.
If your customer doesn't want to spring for the custom software, develop a simple GUI that allows a person to take an address and split it manually. You'd delete the address row with the old format and insert the row with the new address format.
It wouldn't take long for typists familiar with your addresses to manually make 100,000 changes. Of course, it's up to the customer if he wants to spend the money on custom software or typists.
But you shouldn't be stuck with the data cleaning bill, either.
I realize that this is an old question, but for future reference, I still decided to add an answer using regex (also so I don't forget it myself). Today, I ran into a similar problem in Excel, in which I had to split the address in street and house number too. In the end, I've copied the column to SublimeText (a shareware text editor), and used a regex to do the job (CTRL-H, enable regex):
FIND: ^('?\d?\d?\d?['-\.a-zA-Z ]*)(\d*).*$
REPLACE FOR THE HOUSE NUMBER: $2
REPLACE FOR THE STREET NAME: $1
Some notes:
Some addresses started with a quote, e.g. 't Hofje, so I needed to add '?
Some addresses contained digits at the start, e.g. 17 Septemberplein or 2e Molendwarsstraat, so I added \d?\d?\d?
Some addresses contained a -, e.g. Willem-Alexanderlaan or a '
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We typically interface with a RDBMS through SQL. I.e. we create a sql string and send it to the server through JDBC or ODBC or something similar.
Are there any RDBMS that allow direct interfacing with the database engine through some API in Java, C#, C or similar? I would expect an API that allows constructs like this (in some arbitrary pseudo code):
Iterator iter = engine.getIndex("myIndex").getReferencesForValue("23");
for (Reference ref: iter){
Row row = engine.getTable("mytable").getRow(ref);
}
I guess something like this is hidden somewhere in (and available from) open source databases, but I am looking for something that is officially supported as a public API, so one finds at least a note in the release notes, when it changes.
In order to make this a question that actually has a 'best' answer: I prefer languages in the order given above and I will prefer mature APIs over prototypes and research work, although these are welcome as well.
------------------ Update ----------------
Looks like I haven't been clear enough.
What I am looking at is a lower level API, sort of what the RDBMS probably use internally. RDBMS have the concept of an execution plan, and the API I am looking for would allow us to actually execute an execution plan without specifying the intended result, using SQL or similar.
The very vague idea behind this is to implement a DSL which translates directly to RDBMS system calls, without going through SQL or similar.
Trying to explain it in yet a different way: When e.g. Oracle gets fed with a SQL statement, it parses that statement, creates an execution plan out of it and finally executes the execution plan using some internal API, which probably allows things like: retrieving a specific row from a table, retrieving a range or rowids from an index, joining to sets of rows using a hash join and so on. I am looking for that API (or something similar for an RDBMS where this is available)
---------- Another update after comment by Neil ----------------
I think it would be appropriate to consider the API I am looking for the 'ISAM' level as in the second bullet point on this article: http://en.wikipedia.org/wiki/ISAM
You may want to check out the following Wikipedia article for a list of interfacing alternatives to SQL for relational databases:
Wikipedia: SQL: Alternatives to SQL
The list includes (in alphabetical order):
.QL - object-oriented Datalog
4D Query Language (4D QL)
Datalog
Hibernate Query Language (HQL) - A Java-based tool that uses modified SQL
IBM Business System 12 (IBM BS12)
ISBL
Java Persistence Query Language (JPQL)
LINQ
Object Query Language
QBE (Query By Example)
Quel
Tutorial D
XQuery
There is LINQ for .NET/C#. An example of what that would look like is:
var results = from row in db.SomeTable
where row.Key == 23
select row;
Which you can write in "natual" C# like so (that is, the above is syntactic sugar for):
var results = db.SomeTable.Where(row => row.Key == 23);
JDBC and ODBC already have what you need.
Try looking at cursors, for example this.
The syntax will not be as compact as in LINQ for example, but you'll get your rows through which you'll be able to iterate.
You might also want to check for object relational mapping, because I assume that's what you are ultimately looking for.
Furthermore, you will probably find that LINQ and other approaches work well with single row updates and with simple retrievals, but that for general database work (multiple row updates, complicated retrievals, aggregates, etc) there is nothing like SQL. SQL is and will be the most natural way to communicate to RDBMS, since it is the native language for RDBMS.
If you don't want to use SQL you will have to either use
a) one of approaches described at here or here. Keep in mind that these are full blown API's which map to SQL and that at the end they are essential no simpler and where they differ in pardigm, usually not as effective (unnatural fro RDBMS).
b) Write your own data abstraction layer (possibly using one of the frameworks mentioned under a) providing natural methods for your objects to talk to the database. This way you'll get the best of both worlds and exactly what you need. Although this really shines in larger projects.
The stuff I was looking for is called ISAM as correctly pointed out by Neil Butterworth.
So the wikipedia article http://en.wikipedia.org/wiki/Isam gives some points to start further research.
If you happen to find this useful please upvote Neils comment above.