I asked this over on Superuser and it was suggested I try this here:
Can anyone recommend a quality source to learn databases? I am changing careers and have no background in computers but this is what I have chosen to do now.
I was thinking of taking an intro course at a community college but I have no problem teaching myself with a book and some software. I am looking to accelerate my learning curve and don't want to spend an entire semester on an introductory course if there is something better out there.
Any suggestions are welcome. Thank you.
Edit:
Thank you for the feedback. The MS site and Oracle look promising.
I am pursuing a career in software development. I have taken C++ and C# at a community college and was accepted to a masters program for the spring. What level of database knowledge/implementation is required to program in C++ at the master's level and not get handed your lunch?
I guess I need to know how databases are used in programming. I don't have the common core of experience in order to explain the question more thoroughly without tangentially departing into illusory ideals of a programming career.
At any rate, what you have provided is enough to get me going and it will, I am sure, uncover further areas of interest.
Thank you kindly.
There's a whole lot of aspects of "learning databases":
administering databases
designing databases (modeling)
implementing databases (might require adding business logic into triggers and stored procedures).
using databases (and this might be 'writing a query' to aspects of data mining)
And then there's what type of database. Most people these days assume RDBMS, but there's the push towards NoSQL and tuples stores, etc.
There's no one good answer without a little more information about what you're trying to do.
In addition to what people here would consider as database-related jobs (DBA, database developer, data modelling analyst), there are a lot of semi-technical jobs around that refer to themselves as "database people". In particular, you get report analyst -- often using tools like Crystal Reports, Cognos, SSRS -- and business analysts who work on large customer databases, often defining more how the data should be used in various marketing activities than doing much coding. So it would be up to you to decide if you wish to have a more "business" aspect to your career goal, or to work in data entry/management, or do development and design, or to become a specialist admin certified in a particular vendor's software.
In all cases, however, given you start from scratch, some understanding in how relational database systems work would be beneficial. Someone mentioned Element K courses. Personally, I've found the SQL Zoo interactive online course particularly engaging, and have used it with new staff who had to get up to speed with SQL skills in a short time. Also, this tutorial looks well done. For self-study, I recommend the Head First book series, as in Head First SQL. All these recommendations are extremely SQL-centric, though.
Microsoft also offers tutorials that go with Access and SQL Server Express, but I'd warn not to become locked in. SQLite is a free and extremely lightweight RDBMS, which is perfect for trying things out, either using a programming language (if you know one -- if not, I recommend Python).
As for recommending a provider, you're not even saying which country you're in (though from mentioning "community college" I guess it's the US), what your budget and mobility are like etc, so it's hard to decide. Maybe a mentor or advisor at your community college could help?
The IEEE Computer Society has some online Element K database courses available for members. IEEE runs memberships by the calendar year. Professional membership dues are $50 for a half year and $99 for a full year of professional membership. Student memberships are $40 and $20 for full and half year, respectively. This might be less than the cost of one course.
ACM has some online database courses in their catalog also. They also use Element K, so it seems likely they are the same courses. A full membership is also $99 per year, student is $19 per year. (Their membership year starts when you join.)
I assume your goal is to get a job, since you mention you are changing careers.
I understand you wish to accelerate your learning curve. Make sure you do lots of hands-on work, then, to make sure you know how to do things and have skills in databases. The skills, as they say, pay the bills.
I don't know what your background in computer programming, computer science, or information science / managed information science is. If you have some background into those topics, you might be able to make it into the stuff I recommend below.
Most databases are relational in businesses. Depending on the business, they run different datbases. The two really big ones are Oracle and SQL Server.
I've known a couple of friends who learned databases (and other enterprise software) by going online and reading as much documentation as they could put their hands (mouse?) on the Oracle and SQL Server websites, and for other enterprise software. They went and applied for jobs, had enough business sense / charisma, could read/write American business English well, and were good enough to get the job with little/no experience, and have done very well. It pays their bills, and is a stepping stone to bigger things. You might be able to do the same. Go on the Oracle or Microsoft websites, and grab the documentation. Read as much of it as you can, circle words you don't know, try to find the definitions. Find a local guru (that's the main advantage of the community college, they have smart people with communication skills who can help), and talk with them.
If your a tremendous reader, you could do this in a month.
EDIT:
As to how much "database" knowledge you need to know to get into your master's...
It depends on the program; I'm going to assume your'e going for a professional program and not a academic one. Depending on the master's program, you may/may not need to know databases. Consult your professor or advisor to see if this is something you could tackle right away.
You need to know, ultimately, how to "talk" to a database. Think of this like trying to do business with folks in a foreign country:
You'll need to learn the language (relational databases use a language called SQL; make sure you know how to formulate a basic query (SELECT), and modify the data in the database (INSERT / UPDATE / DELETE)).
Make sure you know the culture (what is a table, what is a row, what is a column, what is a tuple, what are keys (foreign/primary/candidate/alternate/super), what are triggers, what are the normal forms, what is an ERD diagram, what is relational theory)
Make sure you have safe transportation (learn APIs to communicate with the database in C++ and C#. Learn how you can run SQL queries on the database from your app and get resulting data back inside your app. Perhaps learn about ORM tools and how to get/set data that way).
The above is what an intro course covers.
Related
I have experience with various versions of SQL Server and Oracle and my general sense is that, deserving or not, Oracle probably has a better reputation for being the preferred database although I sense MS has been closing ground for some time and sometimes even claiming that it outperforms Oracle in situations x,y, and whatever, a close cousin to z.
A friend of mine who works for the gov't has told me that "they can't use either of those databases because they aren't "robust enough" - or something to that effect and that they had to use IBM's DB2 database.
I'm would expect this to be a very difficult question to answer in such broad terms, but could someone just give me an idea as to which db products are generally regarded as being powerful enough (or whatever word you want to apply) for large size high volume enterprises?
If you want to throw in your perspective of how reality differs from general public perception, I'd be interested, too.
My gut tells me that either of these three products could probably be used o successfully implement the largest of enterprises if you know how to design and implement it, but again, I am looking for a little bit of what one product might have over the other vs. public perceptions, deserved or undeserved.
..and if you cancel this question, help me understand why subjective is a tag.:-)
Your gut is largely correct and a good argument can be made for any of the three. Keep in mind that what is used in any given Government, Corporate or other enterprise environment is largely a function of who got to the decision maker first or who the decision maker trusts. That is, the person setting policy may not be a domain expert at all but nonetheless has the power to dictate policy because of their position in the hierarchy. If a given government department will only use DB2, I'd suggest that you take that "evidence" that DB2 is the "best" or "most robust" database with a very large grain of salt.
I have worked many contracts and in the past 10 years I have seen Oracle and PostgreSQL more than anything.
IBM's DB2 is usually used in large enterprise data farms. For scale I have had Oracle systems handle Petabytes of data.
I have had to build systems specifically for database migration and upward scaling. I can tell you sometimes it is a matter of being locked in to a current Database System by application and operations. Meaning it is more cost effective to scale up the system/database in place than; say migrate your Oracle DBs to DB2.
The SQL engine is just one part of the equation, RAM, Disk IO subsystem (SAN), CPUs, fibre etc etc all have to be included.
All of the different engines have different things to offer like RAC, compression of data and backups, partitioning, index/materialized views etc etc etc
Design and proper indexing is also very important...a crappy design on any of these systems will be a crappy system in general
I think our company probably qualifies as one of the "big boys". We are one of the largest solar manufacturing companies in the world. We are exclusively a SQL Server 2005 and 2008 shop. Within the last year we evaluated Oracle as a possible replacement and rejected it. SQL Server manages everything from plant floor operations to ERP. We couldn't be happier with it.
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If someone knew little about databases and wanted to learn about them from scratch, which database would you recommend learning with and why?
MySQL seems ubiquitous, but are there others that are more modern that have learned lessons from the past, or others that are simply nicer or more logical to work with?
Universal compatibility/libraries is not a big concern, unless it is something truly obscure. Mac (Unix) compatibility is a must.
If you just want to be learning the SQL language, and not database administration, I would recommend working with SQLite. If you're on a Mac, it should already be installed. It is a much simpler system than most RDBMSes; there is no server to set up, and client to connect to the server. There are no directories of cryptic files, or anything of the sort. To get started, you can just type:
sqlite3 mydatabase.db
And start working with it. It's so much lighter weight and easier to set up and use than the other database systems that I think it's a good choice for a beginner.
Now, SQLite is a fairly small and lightweight language. If you need be getting into any kind of really complex queries and data mining, I would recommend PostgreSQL. It has a fairly advanced query optimizer, and a pretty long list of SQL features.
And if you want to learn a database as something to use for back-end storage for web programming or something of the sort, MySQL is what I'd choose. It's ubiquitous, supported by almost any web host, and it's pretty fast for very simple queries and updates, which is generally what you need for a web system. It has some real gotchas to avoid when setting it up; you have to choose between several different storage engines, and it can take a lot of work to convince it to actually work with Unicode data. But it's good to learn mostly for its ubiquity.
From what I've seen (at least on the web), MySQL and PostgreSQL are the most ubiquitous free database systems. If you're considering learning one of them, check this comparison out.
You may also want to consider learning SQLite, a "self-contained, embeddable, zero-configuration SQL database engine." It's really easy to get up and going, stored in a single file, and as its description says, has no complicated configuration. SQLite has proved enormously popular as a persistent data store for local apps on the desktop/iPhone. If you're going down this route on a Mac/iPhone, you may also want to check out Core Data, which is an abstraction layer Apple developed on top of SQLite(but can work with pretty much any DB), to simplify working with a database. As a bonus, Core Data includes a nice GUI for forming relationships and entities. You can check out this tutorial for more information.
If you really, truly, want to "learn from scratch", then theory is the first thing to learn. And that means : NOT products, not any. Not DB2, not MySQL, not oracle, not any-of-them.
Hugh Darwen has a freely available e-book entitled "An Introduction to Relational Database Theory". The material is quite "accessible" and quite unlike most other theory textbooks. It's also the accompanying textbook for his university course on database technology.
Chris Date has several books, of which "Introduction to database systems" is the most comprehensive, also the standard textbook in the field, but maybe a little too abstract for some.
If you think that all you need is "just to know a product" and that you can do equally well "without all that theory", then in that case, please disregard this response, because the wording of your question is dishonest.
Sad thing about databases is that each and every one works bit differently. I would most likely pick MySQL first and play with it a bit. Then get PostgreSQL and do the same.
If you need to use databases in corporate environment then I would aim to test also Oracle and SQL Server which both have express versions that can be installed free for yourself.
http://www.microsoft.com/express/sql/download/
http://www.oracle.com/technology/software/products/database/index.html
At start all databases are more or less confusing but I would pick MySQL as first because it can do most of the basic functionalities and has a lot of help available.
I'd go with mysql. It's easy to setup, easy to mess around with via with mysql client, and it's well documented. If you're just starting out, you probably won't need most of the features offered by other databases, like stored procedures and the like.
First of all, MySQL is both ubiquitous and modern.
ANSI SQL is more or less the same in all RDBMs, so you can learn any of them and you'll be good.
Once you've mastered ANSI SQL, then all you've got left is the localized solutions for each one of them, which won't be portable to other systems - and so, totally discouraged to use, unless they simplify your tasks in a way justifying it.
MySQL, PostgreSQL, SQLite - pick one. PostgreSQL is more like Oracle, and in my opinion a bit more mature. It's had stored procedures, triggers, and referential integrity longer than MySQL has. I'll admit that I have both installed, but I use MySQL more often because it's quick and easy.
But do be aware that non-SQL alternatives are out there and growing in importance. BigTable, object databases like db4o, are worth being aware of. "No SQL" is out there.
If you are just getting your feet wet, MYSQL is a great one to start with. Easy install on any platform, great community support and lots of free tools to work with (SQLYog is a favorite of mine).
I agree that theory is very important. Depending on how you learn best, digging in and tinkering may be the thing to do before you try to absorb 40 years of thought on relational systems.
Codd and Date are legends in the field and can help you understand the broader points of relational theory, but are hard to absorb before you have context for the topic.
If you are looking for more pragmatic/immediate guidance, I'd suggest a book like "Databases for Mere Mortals" and anything written by Joe Celko.
Once you get comfortable with the basics, there are lots of other platforms to explore as well. As mentioned above, SQLLite and PostGres are two other great choices for the Mac OS.
If you want to learn SQL : the best way is to choose database who implement more features of the SQL standard. So I would recommand Firebird or PostgreSQL
I might be "sidetracking" a bit with this answer, but I think we're in the same situation!
Check out the "The Manga Guide to Databases"! I haven't read it myself yet, but it's on the way in the mail as we speak! I've heard good things about it from friends and colleges, and it's got some good reviews as well. Albeit a bit "controversial," it's supposed to be a fun and surprisingly in-depth introduction to fundamental techniques and principles!
Alex wrote: "Reading a textbook without incrementally testing your knowledge on an actual database is not going to produce good results for the majority of people."
My book and my university course both use Dave Vooorhis's Rel for that very purpose.
Hugh
A database in the cloud: Amazon EC2, Google App Engine or Microsoft Azure
I'm part of a software development company where we do custom developed applications for our clients.
Our software uses MS SQL Server and we have encountered some customers which do not have a DBA on staff to manage the databases or if they do, they lack the necessary knowledge to perform their job adequately.
We are in the process of drafting a contract with one of those customers to provide development services for new functionality on our software during the next year, where they have an amount of hours available for customization of our software.
Now they want us to include also a quote for database administration services and the problem is that they are including a clause that says that those services will be provided only when they request it.
My first reaction is that db administration is an ongoing process and not something that they can call us once a month to come for a day or two. I'm talking about a central 1TB+ MSSql Cluster and 100 branch offices with MSSql Workgroup edition.
My question is for any suggestions on how I could argue that there must be a fixed amount of hours every month for dba work and not only when their management thinks they need it (which I’m guessing would only be when they have a problem).
PS: Maybe this will be closed as not programming related. But I'm a programmer and I have this problem. My work is software development but i don't want to lose this client and the only solution I can think of is to find a way for the client to understand the scope so we can hire a qualified DBA to provide them with the service they require.
Edit: We are in a Latin American country with clients in the Spanish speaking region. My guess is that in more developed countries there is a culture that knows how delicate the situation is.
This is definitely one of those 'you can lead a horse to water, but you can't make them drink' situations.
My recommendation here would be to quote the DBA services as hourly, and make the rate high enough that you can outsource the work if you decide you want to. When (not if) the SQL servers start to have problems, the firm is on the hook.
I would also recommend that you include in your quote a non-optional 2 hour database technology review once per year. This is your opportunity to say 'You spent XXX on database maintenance this year, most of which was spent fighting fires that could have been easily avoided if you had just spent XXXX/4 and hired a DBA. We care about you as a customer, and we want you to save money, so we really recommend that you commit to using a DBA to perform periodic preventative maintenance'.
I would also recommend that you categorize any support requests as having root cause b/c of database maintenance vs other causes. This will let you put a nice pie chart in front of the customer during their annual review (which they are going to pay you to perform). It is critical to manage the perception so they don't think your code is causing the problems. You might even go so far as to share these metrics (db related issue vs non-db related issue) with them on a quarterly basis.
Sometimes people need to experience pain before they change. The key is to not be in between the hammer and their thumb as they learn the lesson, and hourly quoted work is one way of doing this.
As a side note, this sort of question is of great interest to a large number of developers. I'd say that this sort of thing could impact a programmer's quality of life more than any algorithm or library question ever could. Thanks for asking it!
No DBA on a system that size is a disaster waiting to happen. If they don't understand that, they are not qualified to run a database that size. I'd recommend that they talk to other companies with similar sized databases and have them ask them about their DBAs and what they do for them, and if they think they could survive without them.
Perhaps the link below from MS SQL Tips could give you some good talking points. But people who aren't technical wont respond to a technical explanation of the necessity of good DBA you are likley going to have to work toward proving the cost of bad DBA. Work out the worst case scenarios and see how they feel about them. If you can make it seem like a good financial move (and I think we all know it is) it will be an easy sell.
http://www.mssqltips.com/tip.asp?tip=1278
I'm a research assistant for a university. We're retooling our Software Architecture subject, hoping to "modernize", and address some of the teaching and collaborative learning issues we've discovered in past semesters.
Students are asked to rapidly build a prototype of their architectured system using Eclipse.
For persistence, we've guided students to HSqlDb.
Last semester we received significant feedback that writing the Data Access Layer and mapping to OO has taken alot of time. This plumbing work could be better spent on more relevant things, like scaling, end-to-end perf or satisfying more scenarios.
In a real-world production, I'd pick an ORM tech, like Hibernate, but the subject is already too complex to teach yet another technology (and Hibernate is a massive one to learn for students IMHO).
So, my questions to the SO community:
Should we consider giving students an object oriented database (if they still exist)? This saves time on ORM and plumbing
Should we stick with RDBMS and tell students to roll their own ORM?
Should we point students to a lightweight, simple ORM?
Remember, this isn't real world, but we'd like to teach real world skills as much as possible. Teaching ORM not as important as getting students to rapidly prototype a system that satisfies the scenarios.
I'm a C# dev at heart but the students are only familiar with Java when they come into the subject.
I have to wholeheartedly disagree with the use of ORM in an educational environment. You need to be able to walk before you run, and utilizing ORM eliminates a very important step in the learning process regarding using a relational database in an application. You should stick to a VERY lightweight data access framework--one that requires students to write their own SQL and (at best) doesn't allow this scope of the code to be tied to the UI or (at least) doesn't require it.
I am admittedly unfamiliar with the Java world as it relates to actual enterprise development, but I realize (somewhat begrudgingly) that it's THE environment in the educational system. While I believe that students should be exposed to .NET, that's an argument for another time ;) In any even, I'm quite certain that there's some sort of framework out there that satisfies this.
I'd be willing to wager that there is something out there that provides some code generation functionality. At my old job, we only made use of the .NET database libraries to the point of (relatively) low-level reading of the data from the database. We didn't use any of the repositories or change-tracking technologies, but instead rolled our own. SQL commands were written by hand, but the framework still provided type safety and rich designer support. My point here is that both are possible. I would suggest finding something similar to this in Java, requiring the students to hand-code one or two of these adapters to gain an understanding of what goes into them, then have the code generator do the other "gruntwork" plumbing based on their SQL statements.
Don't use any SQL generation. You MUST be able to write the SQL before you let the computer do it for you. The second you use ORM to do something that you don't know how to do in SQL is the second that you've lost control of your database model, and they need to understand that.
As someone who embraced OO heartily, and RDBMS grudgingly... I would encourage, even beg, computer science departments to keep theory and practice of relational databases in the foreground. If that can be done even while you use an ORM for the OO classes, then go for it. But I'd prefer to see students coming out of college understanding that OO - relational mapping is hard, and why it's hard, and that this does not mean that the relational model is broken.
Not very broken, anyway.
If the primary goal is for the students to learn, then I think using an RDBMS would be the better approach here - they already have to grok the object model on the application side, so reconciling a relational structure into an overall architectural portfolio is an important skill.
Regarding providing an ORM such as Hibernate, I don't really agree that it is something massive for students to learn. One of the best things about Hibernate is that its difficulty level is fairly well correlated to how deep you dig into it. It has a very low barrier of entry (less than a day IMO) to get rolling with the basics, and often the basics are all you need - especially for something like a prototype, which is what you said is the goal of this activity. Certainly it does not require study to such a degree that it will stick with the students beyond the scope of the course. Basic Hibernate use can be a throwaway skill.
So to summarize, I recommend sticking with an RDBMS and providing an ORM like Hibernate.
Take a look at DataObjects.Net - is shares benefits of OR/M framework as well as of object database (if built-in storage providers are used), allowing to transparently migrate between supported storages.
It is quite advanced from the point of architecture and extensions: check out e.g. this post about its query optimization techniques.
I think it depends a lot on what the students know coming into the course. The reason I say this is that it's probably best to start with something they are all familiar with and move forward from there. In my experience, most students understand what objects are and how to use them, so presenting SQL tables as objects seems like a great place to start.
If you agree with me so far, then you might also agree that ORM is a great way to transition young programmers from their comfort zone of object orientated programming into a new world of database programming.
I'm not really familiar with the tools available for Java to implement ORM, but I was able to pick it up in C# (using LINQ to MySQL) in just a few days (after failing miserably at trying to learn PHP for several weeks). If implementing the projects in C# is a possibility, the great thing about using LINQ is that it gives students a feel for how the queries might look in SQL, without leaving their comfort zone of OOP (assuming they are at least somewhat comfortable with developing in .NET). This allows you to teach the concepts of database programming, without spending too much time talking about the implementation of it. Then, once they've mastered the concepts, you can roll back and show them how to perform a similar implementation outside of OOP (using SQL, PHP, JSP, etc.)
Not to mention, it gives them a great preview of how they can use the latest .NET technologies to do some pretty advanced stuff without too much effort (which is probably more beneficial to them in the long term anyway).
Good luck!
In my experience, this has been a contentious issue between "backend" (database developer) and "frontend" guys (application developer, client and server side).
There have been many heated pub discussions on this subject.
I just want to know is it just people have different mindsets, or lazy to learn more and feel comfortable in what they know, or something else.
I might re-phrase the question: why do (some) application developers think they can do "database stuff" without actually bothering to understand it properly? Whereas database developers do not (in general) assume they can write a good application without some training and experience!
It is about levels of abstraction. A database is the lowest level of abstraction in a typical business application (software-wise). It is much more likely that a developer working on an outer layer of the abstraction would have knowledge of an inner layer than a developer in an inner layer would know about the outer layer.
This is because inner layers of abstraction best perform when they are ignorant of the outer layers who depend on them.
So a designer in the presentation layer of a website may know a bit about the server-side code they depend on because they interact with it. But the developer working on the server does not need to know anything about design at all.
I would say it's on a need to know basis. Applications developers often need to know how to connect to databases, add records, delete records etc... This is taken further with new technologies such as LINQ where developers can write database queries within their actual code.
Database developers on the other hand only really need to know how to write database queries as that is their job and probably won't need to worry about the code at application level.
Because programmers very often must understand and interact with databases to do their job, but DBAs very often don't need to do any programming (outside of the DBMS) to do their jobs.
I believe it stems from the fact that programming in sql looks easy, and to get started you have to have a small amount of knowledge (Really for a programmer to learn SELECT * FROM Table is pretty easy). Application programming is not the same way. It becomes very complex in a small amount of time, and that discourages a lot of people. Now I am not saying that database people are any less intelligent it is just what they do looks easier than building applications.
If you develop applications, then the chances are, that sooner or later, you'll have to connect an app to a back-end.
The opposite is not as true.
I think it stems from necessity. If you consider the roles of each person, a programmer needs to to database related stuff far more than database workers need to do programming tasks.
From my experience, having developed both "databases" and "applications" (following your nomenclature...), I guess there's a big difference in state management.
Properly designed databases are always in a "clean" state, and every transaction keeps this consistency. So when developing a database, you have to very clearly specify your data abstractions into tables and which updates are legal and so on.
I've found that most application developers (myself included :)) do a very sloppy job in keeping this consistent state in the application. Any non-trivial interface has many more possible states to manage than a modest database, and it's not as easy to make sure it's always in a clean state. It's also harder to analyze every possible sequence of steps that users will perform.
From my experience, the application developers don't do all the database stuff. Consider all the administration that is related to the databse, backups, replication, etc.
A typical DBA (at least on most of the projects I've been involved to) takes care about everything that is related to project databases - all administration, cooperates with application developers on performance tuning, gives advices about SQL used by the app, does some of the stored procs coding, creates (or, at least reviews and consults) physical DB designs, etc.
So, aren't the database guys "lazy", or "fine with what they already know" just from an application developer's perspective? I'm an app developer myself and there is a whole lot of things that I just don't know about the DBs we're using on our projects.
Part of my education ensured I got a decent understanding of how Databases work. I went into the field expecting to do database work, and a lot of it. I'm a web app guy; it comes with the territory I guess.
My two jobs as a developer have been at two shops that would best be described as tiny (2 people myself included, and then just me) and tiny (3 developers, briefly having a fourth). I have not observed an immediate business need for, nor worked anywhere that had the resources to employ a dedicated DB guy. I can envision some scenarios where that would change (including a new job :P).
As to the rest, I agree that abstraction is also a factor and as developers we're way up on top/outside looking in. I can't imagine doing web app development without DB skills, and I consider Sql/DB Management to be both an important tool and an area I need to stay sharp in.
I'll add that I treat the database side as its own field. There's skills that translate between the two, but there's a lot of specialized knowledge I need to acquire to get better at it, and that being a good programmer doesn't necessarily mean I'm doing a good job on the back end either (fortunately, I'm not a good programmer ;) ). Also, I'm pretty sure that's what she said.
2 reasons:
DB Vendors facilitate bad SQL, and
SQL is hidden from view while
application UI is front and center.
Most naive developers think SQL is a procedural language and write it as such because vendors ensure that the tools exist so that they can do so. DBAs know that good SQL is set-oriented and has optimization principles that are totally different from those involved in application programming.
The visibility aspect makes it so the application developers can write bad SQL against a database and get it to perform in a marginal way, and no one ever sees quite how bad it is. When a DBA writes an application, there are immediate critiques on its appearance and behavior because it's directly visible to the end user.
Good question. Actually why developers do Database Stuff because where no dedicated Database guys then developers have to do that. But a company have Database Guys also have Development guys.
:) what is your idea ?