78 lines
3.0 KiB
Markdown
78 lines
3.0 KiB
Markdown
# Getting Started
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These exercises lean on Test-Driven Development (TDD), but they're not an
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exact match.
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## Setup
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You'll need access to a mounted Oracle DB. If you don't have one already
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installed, here are a few options:
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* download VirtualBox from Oracle and run one of the freely
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available images; at the time of writing, the easiest to get started with
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at the time of writing might be _Database App Development VM_. The
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image is quite large...
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* download and install the a version of the Oracle DB itself. Developer licenses
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are free.
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* get a free workspace at https://apex.oracle.com
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**Note**: if you're using the online version of APEX, compilation errors will
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not be indicated very clearly when working in _SQL Commands_ - you will simply
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get "Error at line XX: PL/SQL: Statement ignored"... More insight can be
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found using the _Object Browser_ and navigating to the object you created
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(select either _Packages_ or _Procedures_ in the dropdown menu showing _Tables_,
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depending on what you created for the exercise). Also, when you run statements,
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"run" each individual `create` statement individually by selecting its text.
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APEX does not seem to like doing too much work at once...
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To work on individual problems, a nice and free way is to use SQL Developer. If
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you don't want to use yet another IDE, you can simply copy and paste your code
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into a terminal / command prompt connected to the database. The files are
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prepared in a way that will simply overwrite the previously compiled version.
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#Exercise
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## Step 1
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Compile the test suite. You can easily do that by copy / pasting (let's call
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that _installing_ for simplicity) into your terminal connected to a mounted
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Oracle database.
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This will fail, complaining that there is no package called `HAMMING#`.
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To fix the error create the package by installing the prepared solution stub.
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Note that you will have to re-install the package body of `UT_HAMMING#`.
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A few words about naming: the `#` at the end of the name signifies that this
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is a package. `UT` means _unit test_. _PL/SQL_ has a maximum identifier length
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of 30 characters, which is why you will find that many words are abbreviated.
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If you've worked with PL/SQL before, you might wonder why the template is a
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package and not simply a standalone function. That would of course also be a
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possibility, but in practice standalone procedures or functions are rarely used.
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## Step 2
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Try to run the test. You will notice that you are missing the function's
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implementation. Create it (see the test package for examples).
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Note that functions have to return a value, so for now just `return null;`.
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## Step 3
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Run the test again. It should now execute, but the test will fail.
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That's where you get to actually implement the function!
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## Wash, Rinse, Repeat
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Only the first test is enabled at first, the others are commented out. To enable
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them, simply delete the `--` in front of the procedure call and they'll run
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when you next install the test package!
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## Submit
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When everything is passing, you can submit your code with the following
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command:
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$ exercism submit hamming#.plsql
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