I've started a new job and am looking at some of their views that they wanted me to get familiar with.
One of the views that I'm going through has 54 SELECTs. I've NEVER seen such a massive View before and after browsing through it, I'm fairly certain that I can optimize it.
What I'm looking for is an easier way to compare the JOINs between each of the selects to find commonality WITHOUT just having to sift through them all by hand.
I'm fairly certain that THAT is what I'll have to do, but I was hoping that someone would have an easier or more efficient and less time consuming way to do this...
Anyone? :)
Update 12/4/2019:
TLDR; I separated each main SELECT into it's own file, then using Notepad++ on the full view code file I found common values to sort and organize each individual SELECT into a folder named the common value. From there I used WinMerge to compare each group of SELECTs in their respective folders against each other to find differences and commonalities. I then started refactoring and minimizing the excessive code (and table calls >.< ) using CTE's (because this is Oracle and a View).
I ended up splitting out the views SELECTs by looking for one of the field names that's a column in the view. This meant that I'd get the beginnings of each SELECT.
I then copied and pasted each one into a different .sql file. I also saved the full view into it's own .sql file.
Using Notepad++ I searched for each instance of the view column name and took down the column value that is the main information needed for the view. Using that information, I grouped each SELECT into a folder based on that value
Once I'd gotten all the SELECTs into their respective folders, I used WinMerge to the SELECTs to the others in their same folder. This helped me to locate commonalities and differences, some differences that would be harder to lump the datasource table into a CTE with the others.
I've since been updating, refactoring, and fixing the view one folder grouped SELECTs at a time.
The project I'm in has had me touching each one of the main code values that I had used to organize the SELECTs into folders, so I WILL end up recoding the ENTIRE view. :)
Identifying similar lines of code is a difficult problem, and as far as I know Clone Doctor is the only program that can do it for PL/SQL.
I only used it once, about 10 years ago. But I remember being surprised at how well it found different lines of code that were really duplicates at a deep level. It wasn't perfect, and had some bugs and took a while to get working. But there's a free trial version.
I have a letter in Word that needs to be sent out to a number of contacts (example of letter). The only thing that needs to change in the letter is the recipients information
(example of how recipients info is stored), but I don't know what the best way to change this info is.
I did a little bit of research and what I've come across is that people either do a search and replace or use fields. I suspect that there is a better method than search and replace since I know exactly where the text needs to change. I'm thinking there might be something similar to named ranges like in excel?
Now this is where I came across fields, but to be honest I don't really understand them. I know they have a name but this whole equation thing throws me off. So my question is how do I change this information in the quickest/most efficient way?
I understand how to access and save word documents and am planning on using a loop to go through each row of contacts one by one, so if you have a solution you can leave that part out (unless you know of a better way!).
I need a way to search my entire Oracle database for a column that contains the value 'Beef'. What I need is the column name and table name so I can complete my query. Beef is an animal feed type and it is a known value in my database. I just don't know where.....
Essentially, we have a very old very clunky application that I am using SQL data sets generated from Toad freeware to get around. The application shows us laboratory testing information for our companies. The catch is you can only look at one company's lab report at a time, and as a I said, it takes FOREVER. We have over 700 companies we regulate so this is not an option (oh and you can't copy any of the fields).
I have already generated a query that gets me 99% of the information I need until I realized I was missing one column value that for some unearthly reason isn't included with the other attributes of the lab samples. We have around 100 or so tables and many of them aren't even in use. It's a poorly organized database and I've tried manually going through it and simply cannot find the stupid column and I have no idea what it could be named (naming conventions here seem not to apply).
A monkey wrench is: although I've done a decent amount of SQL coding for my job I'm not in IT. My job hooked me up with a read-only access of our database so I could run reports for them etc, but I'm not in the IT section so I don't get write privileges. So a lot of solutions I see that use DDL aren't available to me.
I guess it might be relevant, it looks like we're running oraClient10g.
I've tried this code that I got from here: community.Oracle
but as you can see I don't get any results.
I also tried the one suggested here at stackOverflow, but got a litany of errors so I abandoned that pretty quick. (I figured it's because of my read-only privileges and or my version of Oracle).
Any help would be greatly appreciated.
I'm making my project for a-level computing and I reached a problem that im not sure how to solve. Im making something similar to a student information management system and I want a way to store a small list of students maybe 5 to 10 preferably in my program and make reference to them from all forms and so that if something is changed on one of the students maybe a piece of information, that these information is carried to the next form. My teacher has very little knowledge on programming and so im kind of stuck, i have no previous experience with databases or sql however if someone is willing to break it down ill be very grateful and ive got a good understanding of arrays. My deadline is the 10th of may so asap please, thanks
- kyle
If you prefer simplicity I would stick to a CSV file or XML. I found a website which an end-to-end tutorial on how to create the XML and add items (students) to it using VB.net as according to your tag. You need only after to read them from the file, but might just as well add new:
http://vb.net-informations.com/xml/how-to-xml-in-vb.net.htm
I would stick with XML (or CSV as preffered) as it is a text file basically so you can see and make changes directly if needed.
I have been working on sql server and front end coding and have usually faced problem formulating queries.
I do understand most of the concepts of sql that are needed in formulating queries but whenever some new functionality comes into the picture that can be dont using sql query, i do usually fails resolving them.
I am very comfortable with select queries using joins and all such things but when it comes to DML operation i usually fails
For every query that i never done before I usually finds uncomfortable with that while creating them. Whenever I goes for an interview I usually faces this problem.
Is it their some concept behind approaching on formulating sql queries.
Eg.
I need to create an sql query such that
A table contain single column having duplicate record. I need to remove duplicate records.
I know i can find the solution to this query very easily on Googling, but I want to know how everyone comes to the desired result.
Is it something like Practice Makes Man Perfect i.e. once you did it, next time you will be able to formulate or their is some logic or concept behind.
I could have get my answer of solving above problem simply by posting it on stackoverflow and i would have been with an answer within 5 to 10 minutes but I want to know the reason. How do you work on any new kind of query. Is it a major contribution of experience or some an implementation of concepts.
Whenever I learns some new thing in coding section I tries to utilize it wherever I can use it. But here scenario seems to be changed because might be i am lagging in some concepts.
EDIT
How could I test my knowledge and
concepts in Sql and related sql
queries ?
Typically, the first time you need to open a child proof bottle of pills, you have a hard time, but after that you are prepared for what it might/will entail.
So it is with programming (me thinks).
You find problems, research best practices, and beat your head against a couple of rocks, but in the process you will come to have a handy set of tools.
Also, reading what others tried/did, is a good way to avoid major obsticles.
All in all, with a lot of practice/coding, you will see patterns quicker, and learn to notice where to make use of what tool.
I have a somewhat methodical method of constructing queries in general, and it is something I use elsewhere with any problem solving I need to do.
The first step is ALWAYS listing out any bits of information I have in a request. Information is essentially anything that tells me something about something.
A table contain single column having
duplicate record. I need to remove
duplicate
I have a table (I'll call it table1)
I have a
column on table table1 (I'll call it col1)
I have
duplicates in col1 on table table1
I need to remove
duplicates.
The next step of my query construction is identifying the action I'll take from the information I have.
I'll look for certain keywords (e.g. remove, create, edit, show, etc...) along with the standard insert, update, delete to determine the action.
In the example this would be DELETE because of remove.
The next step is isolation.
Asnwer the question "the action determined above should only be valid for ______..?" This part is almost always the most difficult part of constructing any query because it's usually abstract.
In the above example you're listing "duplicate records" as a piece of information, but that's really an abstract concept of something (anything where a specific value is not unique in usage).
Isolation is also where I test my action using a SELECT statement.
Every new query I run gets thrown through a select first!
The next step is execution, or essentially the "how do I get this done" part of a request.
A lot of times you'll figure the how out during the isolation step, but in some instances (yours included) how you isolate something, and how you fix it is not the same thing.
Showing duplicated values is different than removing a specific duplicate.
The last step is implementation. This is just where I take everything and make the query...
Summing it all up... for me to construct a query I'll pick out all information that I have in the request. Using the information I'll figure out what I need to do (the action), and what I need to do it on (isolation). Once I know what I need to do with what I figure out the execution.
Every single time I'm starting a new "query" I'll run it through these general steps to get an idea for what I'm going to do at an abstract level.
For specific implementations of an actual request you'll have to have some knowledge (or access to google) to go further than this.
Kris
I think in the same way I cook dinner. I have some ingredients (tables, columns etc.), some cooking methods (SELECT, UPDATE, INSERT, GROUP BY etc.) then I put them together in the way I know how.
Sometimes I will do something weird and find it tastes horrible, or that it is amazing.
Occasionally I will pick up new recipes from the internet or friends, then use parts of these in my own.
I also save my recipes in handy repositories, broken down into reusable chunks.
On the "Delete a duplicate" example, I'd come to the result by googling it. This scenario is so rare if the DB is designed properly that I wouldn't bother keeping this information in my head. Why bother, when there is a good resource is available for me to look it up when I need it?
For other queries, it really is practice makes perfect.
Over time, you get to remember frequently used patterns just because they ARE frequently used. Rare cases should be kept in a reference material. I've simply got too much other stuff to remember.
Find a good documentation to your software. I am using Mysql a lot and Mysql has excellent documentation site with decent search function so you get many answers just by reading docs. If you do NOT get your answer at least you are learning something.
Than I set up an example database (or use the one I am working on) and gradually build my SQL. I tend to separate the problem into small pieces and solve it step by step - this is very successful if you are building queries including many JOINS - it is best to start with some particular case and "polute" your SQL with many conditions like WHEN id = "123" which you are taking out as you are working towards your solution.
The best and fastest way to learn good SQL is to work with someone else, preferably someone who knows more than you, but it is not necessarry condition. It can be replaced by studying mature code written by others.
Your example is a test of how well you understand the DISTINCT keyword and the GROUP BY clause, which are SQL's ways of dealing with duplicate data.
Examples and experience. You look at other peoples examples and you create your own code and once it groks, you don't need to think about it again.
I would have a look at the Mere Mortals book - I think it's the one by Hernandez. I remember that when I first started seriously with SQL Server 6.5, moving from manual ISAM databases and Access database systems using VB4, that it was difficult to understand the syntax, the joins and the declarative style. And the SQL queries, while powerful, were very intimidating to understand - because typically, I was looking at generated code in Microsoft Access.
However, once I had developed a relatively systematic approach to building queries in a consistent and straightforward fashion, my skills and confidence quickly moved forward.
From seeing your responses you have two options.
Have a copy of the specification for whatever your working on (SQL spec and the documentation for the SQL implementation (SQLite, SQL Server etc..)
Use Google, SO, Books, etc.. as a resource to find answers.
You can't formulate an answer to a problem without doing one of the above. The first option is to become well versed into the capabilities of whatever you are working on.
The second option allows you to find answers that you may not even fully know how to ask. You example is fairly simplistic, so if you read the spec/implementation documentaion you would know the answer right away. But there are times, where even if you read the spec/documentation you don't know the answer. You only know that it IS possible, just not how to do it.
Remember that as far as jobs and supervisors go, being able to resolve a problem is important, but the faster you can do it the better which can often be done with option 2.