Oracle SQL certification path?

[polaryeti]

1) Oracle 1Z0-149

2) Oracle Database SQL 1Z0-071

3) Oracle Database 12c: SQL Fundamentals 1Z0-061

4) or any other oracle exams? I've no idea about it.

I've finished learning a 20hrs sql course. It took me probably 100hrs to finish the course as I went slow. I'm confident with the basics. But few things I need more practice on(not that I don't know them but still confused). They're:

1) Aggregate functions and GROUP BY.

2) Transactions & concurrency control

3) Procedures, Views

4) Subqueries

I  thought the obvious next step would be take some oracle certification (I won't give exams as I don't earn that much, just study for the exam).

If there  are other DBA certification except Oracle, do tell me? We use microsoft sql server and mysql at work but I've already learnt enough sql for work. (we just need basic select query at work)

[gizmola]

Oracle database has been around a long time, and has a lot of features and extensions that are specific to it.  If you are not going to use it immediately, or need a certification for a job, I wouldn't recommend going down that rabbit hole, even though I do think that Oracle database is a great RDBMS in many ways, but it is commercial and expensive.  You often see it paired with java/enterprise java applications.  For reasons I won't go into, besides cost, very few people pair PHP with Oracle database.   The open source database closest in design and features to Oracle is Postgresql, so if anything, exploring postgresql would be a step in that direction.

Since you use SQL Server, I would suggest getting certs in that, and in particular, learn about the specific things you listed, like transactions and concurrency (locking), and Views, stored procedures and triggers.  Sprocs and Triggers are very important and highly used in SQL server development (Transact-SQL aka T-SQL), and in Oracle (which has an entirely different stored procedure language).  MySQL also has stored procedures & triggers, but they are not commonly used, in comparison to the way that they are very often baked into applications that use sql server on the backend, as is the case with a lot of .NET applications.

I don't think you can really say you are confident in your SQL knowledge until you are confident in the many ways you can use joins (including self joins), and the use of grouping and aggregation, as these are some of the primary reasons people use relational databases.  It also helps to learn about the way rdbms's work in terms of datatypes, constraints and indexes.  You want to have a good working understanding of the different types of indexes and the ways they overlap with primary key/unique constraints.  You also really need to understand concurrency and locking, as it pertains to each database, and an understanding of transactions as well as "2 phase commit" support.  

While all the major relational database engines have configuration options that can be used to alter the concurrency/locking models, MySQL (and forks like MariaDB)  is particularly different in that it allows for the use of different engines.  For example, the original MySQL engine (myisam) is very different from the popular InnoDB engine that most companies use.  It's a simple example, but MyISAM has no support for transactions, so you can write code that starts transactions and commits or does a rollback, and mysql will happily except that code, when in fact it actually ignores those statements entirely and doesn't support transactions whatsoever.  

You also want to understand how you install and configure these databases, and what options and tradeoffs might be involved in how you set them up.  This affects how a database might/might not recover from a crash/ lose some data/transactions (or not), have backup options, or support replication in various flavors.   With the existence of Docker, it's now much easier to experiment and learn about these databases, and create local test configurations.  

I think it helps to keep in mind, that there are categories of developers (DB Architects & Administrators & DB developers) who specialize in these products, and they have extensive levels of depth to them.  There are some well known experts with books you might be interested in.  A couple off the top of my head, are Joe Celko, who wrote some well known SQL books, and Tom Kyte, who authored many books on Oracle, and was well known for his "Ask Tom" column where he answered oracle questions and demonstrated ways certain problems could be solved.

PHPFreaks is fortunate to have a number of developers who have consistently shared their expertise with relational database design and SQL, so this is still a great place to get advice and in many cases example code.