Databases
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    <p>Do use InnoDB; don't use MyISAM.</p> <p>(OK, OK, unless you absolutely <em>have</em> to, often due to fulltext matching not being available in InnoDB. Even then you're often better off putting the canonical data in InnoDB and the fulltext index on a separate MyISAM searchbait table, which you can then process for stemming.)</p> <p>Do use BINARY columns when you want rigorous string matching, otherwise you get a case-insensitive comparison by default. Do set the collation correctly for your character set (best: UTF-8) or case-insensitive comparisons will behave strangely.</p> <p>Do use ANSI SQL mode if you want your code to be portable. ANSI_QUOTES allows you to use standard double-quoted <code>"identifier"</code> (table, column, etc.) names to avoid reserved words; MySQL's default way of saying this is backquotes but they're non-standard and won't work elsewhere. If you can't control settings like this, omit any identifier quoting and try to avoid reserved words (which is annoying, as across the different databases there are many).</p> <p>Do use your data access layer's MySQL string literal escaping or query parameterisation functions; don't try to create escaped literals yourself because the rules for them are a lot more complicated than you think and if you get it wrong you've got an SQL injection hole.</p> <p>Don't rely on MySQL's behaviour of returning a particular row when you select columns that don't have a functional dependency on the GROUP BY column(s). This is an error in other databases and can easily hide bugs that will only pop up when the internal storage in the database changes, causing a different row to be returned.</p> <pre><code>SELECT productid, MIN(cost) FROM products GROUP BY productcategory -- this doesn't do what you think </code></pre>
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    1. COGreat answer! I would, however, suggest avoiding using mysql's bizzare "feature", that allows you retrieve values from columns, that were not mentioned in group by clause. It simply makes no sense whatsoever. And by avoiding I mean "never ever doing it". Just pretend it produces an error.
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    2. COYes, that's my suggestion too, except when you're grouping by a row's primary key and retrieving other columns from that row. In that case they have a ‘functional dependency’ on the GROUP BY, so it's valid in ANSI SQL and works in other databases. You can of course add all those columns to the GROUP BY clause too, but it's a bit of a pain if there are loads of them.
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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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