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<h1>MySQL/OTP User's Guide</h1>
<p>
MySQL/OTP is a driver for connecting Erlang/OTP applications to MySQL
databases. It is a native implementation of the MySQL protocol in Erlang.</p>
<p>This is the documentation generated from the Erlang source code using EDoc.
The project page is on Github:
<a href="https://github.com/mysql-otp/mysql-otp/" target="_top">https://github.com/mysql-otp/mysql-otp/</a>.</p>
<p>For the reference manual see the <a href="mysql.html">mysql</a> module.</p>
<h2 id="value-representation">Value representation</h2>
<table>
<thead>
<tr>
<th>MySQL</th>
<th>Erlang</th>
<th>Example</th>
</tr>
</thead>
<tbody>
<tr>
<td>INT, TINYINT, etc.</td>
<td><code>integer()</code></td>
<td><code>42</code></td>
</tr>
<tr>
<td>VARCHAR, TEXT, etc.</td>
<td><code>unicode:chardata()</code> [<a href="#vn1">1</a>]</td>
<td><code><<"foo">></code>, <code>"bar"</code></td>
</tr>
<tr>
<td>VARBINARY, BLOB, etc.</td>
<td><code>binary()</code></td>
<td><code><<1, 2, 3, 4>></code></td>
</tr>
<tr>
<td>BIT(N)</td>
<td><code><<_:N/bitstring>></code></td>
<td><code><<255, 6:3>></code></td>
</tr>
<tr>
<td>FLOAT, DOUBLE</td>
<td><code>float()</code></td>
<td><code>3.14</code></td>
</tr>
<tr>
<td>DECIMAL(P, S)</td>
<td><code>integer()</code> when S == 0<br>
<code>float()</code> when P =< 15 and S > 0<br>
<code>binary()</code> when P >= 16 and S > 0 [<a href="#vn2">2</a>]<br>
<code>{decimal, Value}</code> [<a href="#vn3">3</a>] (parameter only)</td>
<td><code>42</code><br><code>3.14</code><br><code><<"3.14159265358979323846">></code><br>
<code>{decimal, 10.2}</code></td>
</tr>
<tr>
<td>DATETIME, TIMESTAMP</td>
<td><code>calendar:datetime()</code> [<a href="#vn4">4</a>]</td>
<td><code>{{2014, 11, 18}, {10, 22, 36}}</code></td>
</tr>
<tr>
<td>DATE</td>
<td><code>calendar:date()</code></td>
<td><code>{2014, 11, 18}</code></td>
</tr>
<tr>
<td>TIME</td>
<td><code>{Days, calendar:time()}</code> [<a href="#vn4">4</a>,
<a href="#vn5">5</a>]</td>
<td><code>{0, {10, 22, 36}}</code></td>
</tr>
<tr>
<td>NULL</td>
<td><code>null</code></td>
<td><code>null</code></td>
</tr>
</tbody>
</table>
<p>Notes:</p>
<ol>
<li id="vn1">When fetching VARCHAR, TEXT etc. they are returned as <code>binary()</code>.
When sending (insert or update) any <code>unicode:chardata()</code> is accepted as
input. In a (possibly deep) list of integers and binaries, the integers are
treated as Unicode codepoints while binaries are treated as UTF-8 encoded
Unicode data. For lists, an error occurs if you try to send invalid Unicode
data, but if the input is a pure binary, no validation will be done. This is
to allow sending binary non-Unicode data for MySQL's binary strings (BLOB,
VARBINARY, etc.).</li>
<li id="vn2">DECIMALs are returned as <code>integer()</code> or <code>float()</code> when the value
can be represented without precision loss and as <code>binary()</code> for high
precision DECIMAL values. This is similar to how the <code>odbc</code> OTP application
treats DECIMALs.</li>
<li id="vn3">DECIMALs can be sent as <code>{decimal, Value}</code> (where Value is a
number, string or binary) but values received from the database are
never returned in this format.</li>
<li id="vn4">For <code>DATETIME</code>, <code>TIMESTAMP</code> and <code>TIME</code> values with fractions of
seconds, we use a float for the seconds part. (These are unusual and were
added to MySQL in version 5.6.4.)</li>
<li id="vn5">Since <code>TIME</code> can be outside the <code>calendar:time()</code> interval, we use
the format as returned by <code>calendar:seconds_to_daystime/1</code> for <code>TIME</code>
values.</li>
</ol>
<h2>Copying</h2>
<p>Copyright 2014-2021 The authors of MySQL/OTP. See the project page at
<a href="https://github.com/mysql-otp/mysql-otp" target="_top">https://github.com/mysql-otp/mysql-otp</a>.</p>
This library is free software licensed under the GNU LGPL which allows you to
use it in proprietary applications as well as free software applications with
other licenses. This documentation is generated from the source code and thus
goes under the same license as the library itself.
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