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<a href="#nested-classes">Data Structures</a> |
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<div class="headertitle"><div class="title">zdbpp.h File Reference</div></div>
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<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><p><a class="el" href="zdbpp_8h.html" title="zdbpp.h - C++ Interface for libzdb">zdbpp.h</a> - C++ Interface for libzdb </p>
<center><img src="database++.png" alt="" class="resp-img" style="width:700px" class="inline"/></center><p>A modern, type-safe way to interact with various SQL databases from C++ applications.</p>
<h2><a class="anchor" id="autotoc_md28"></a>
Features</h2>
<ul>
<li>Thread-safe Database Connection Pool</li>
<li>Connect to multiple database systems simultaneously</li>
<li>Zero runtime configuration, connect using a URL scheme</li>
<li>Supports MySQL, PostgreSQL, SQLite, and Oracle</li>
<li>Modern C++ features (C++20 or later required)</li>
</ul>
<h2><a class="anchor" id="autotoc_md29"></a>
Core Concepts</h2>
<p>The central class in this library is <code>ConnectionPool</code>, which manages database connections. All other main classes (<code>Connection</code>, <code>PreparedStatement</code>, and <code>ResultSet</code>) are obtained through the <code>ConnectionPool</code> or its derivatives.</p>
<h3><a class="anchor" id="autotoc_md30"></a>
ConnectionPool and URL</h3>
<p>The <code>ConnectionPool</code> is initialized with a <code>URL</code> object, which specifies the database connection details:</p>
<div class="fragment"><div class="line"><a class="code hl_class" href="classzdb_1_1URL.html">zdb::URL</a> url(<span class="stringliteral">"mysql://localhost:3306/mydb?user=root&password=secret"</span>);</div>
<div class="line"><a class="code hl_class" href="classzdb_1_1ConnectionPool.html">zdb::ConnectionPool</a> pool(url);</div>
<div class="line">pool.start();</div>
<div class="ttc" id="aclasszdb_1_1ConnectionPool_html"><div class="ttname"><a href="classzdb_1_1ConnectionPool.html">zdb::ConnectionPool</a></div><div class="ttdoc">Represents a database connection pool.</div><div class="ttdef"><b>Definition</b> zdbpp.h:1794</div></div>
<div class="ttc" id="aclasszdb_1_1URL_html"><div class="ttname"><a href="classzdb_1_1URL.html">zdb::URL</a></div><div class="ttdoc">Represents an immutable Uniform Resource Locator.</div><div class="ttdef"><b>Definition</b> zdbpp.h:331</div></div>
</div><!-- fragment --><p>A ConnectionPool is designed to be a long-lived object that manages database connections throughout the lifetime of your application. Typically, you would instantiate one or more ConnectionPool objects as part of a resource management class or in the global scope of your application.</p>
<h3><a class="anchor" id="autotoc_md31"></a>
Best Practices for Using ConnectionPool</h3>
<ol type="1">
<li>Create ConnectionPool instances at application startup.</li>
<li>Maintain these instances for the entire duration of your application's runtime.</li>
<li>Use a single ConnectionPool for each distinct database you need to connect to.</li>
<li>Consider wrapping ConnectionPool instances in a singleton or dependency injection pattern for easy access across your application.</li>
<li>Ensure proper shutdown of ConnectionPool instances when your application terminates to release all database resources cleanly.</li>
</ol>
<p>Example of a global ConnectionPool manager:</p>
<div class="fragment"><div class="line"><span class="keyword">class </span>DatabaseManager {</div>
<div class="line"><span class="keyword">public</span>:</div>
<div class="line"> <span class="keyword">static</span> ConnectionPool& getMainPool() {</div>
<div class="line"> <span class="keyword">static</span> ConnectionPool mainPool(<span class="stringliteral">"mysql://localhost/maindb?user=root&password=pass"</span>);</div>
<div class="line"> <span class="keywordflow">return</span> mainPool;</div>
<div class="line"> }</div>
<div class="line"> </div>
<div class="line"> <span class="keyword">static</span> ConnectionPool& getAnalyticsPool() {</div>
<div class="line"> <span class="keyword">static</span> ConnectionPool analyticsPool(<span class="stringliteral">"postgresql://analyst:pass@192.168.8.217/datawarehouse"</span>);</div>
<div class="line"> <span class="keywordflow">return</span> analyticsPool;</div>
<div class="line"> }</div>
<div class="line"> </div>
<div class="line"> <span class="keyword">static</span> <span class="keywordtype">void</span> initialize() {</div>
<div class="line"> <span class="keyword">static</span> std::once_flag initFlag;</div>
<div class="line"> std::call_once(initFlag, []() {</div>
<div class="line"> <span class="comment">// Configure and start main pool</span></div>
<div class="line"> ConnectionPool& main = getMainPool();</div>
<div class="line"> main.setInitialConnections(5); <span class="comment">// Example value</span></div>
<div class="line"> main.setMaxConnections(20); <span class="comment">// Example value</span></div>
<div class="line"> main.setConnectionTimeout(30); <span class="comment">// 30 seconds timeout</span></div>
<div class="line"> main.start();</div>
<div class="line"> </div>
<div class="line"> <span class="comment">// Configure and start analytics pool</span></div>
<div class="line"> ConnectionPool& analytics = getAnalyticsPool();</div>
<div class="line"> analytics.setInitialConnections(2);</div>
<div class="line"> analytics.setMaxConnections(10);</div>
<div class="line"> analytics.start();</div>
<div class="line"> });</div>
<div class="line"> }</div>
<div class="line"> </div>
<div class="line"> <span class="keyword">static</span> <span class="keywordtype">void</span> shutdown() {</div>
<div class="line"> getMainPool().stop();</div>
<div class="line"> getAnalyticsPool().stop();</div>
<div class="line"> }</div>
<div class="line">};</div>
</div><!-- fragment --><h2><a class="anchor" id="autotoc_md32"></a>
Usage Examples</h2>
<h3><a class="anchor" id="autotoc_md33"></a>
Basic Query Execution</h3>
<div class="fragment"><div class="line"><span class="keyword">auto</span>& pool = DatabaseManager::getMainPool();</div>
<div class="line"><span class="keyword">auto</span> con = pool.getConnection();</div>
<div class="line"> </div>
<div class="line">ResultSet result = con.executeQuery(<span class="stringliteral">"SELECT name, age FROM users WHERE id = ?"</span>, 1);</div>
<div class="line"><span class="keywordflow">if</span> (result.next()) {</div>
<div class="line"> std::cout << <span class="stringliteral">"Name: "</span> << result.getString(<span class="stringliteral">"name"</span>).value_or(<span class="stringliteral">"N/A"</span>)</div>
<div class="line"> << <span class="stringliteral">", Age: "</span> << result.getInt(<span class="stringliteral">"age"</span>) << std::endl;</div>
<div class="line">}</div>
</div><!-- fragment --><h3><a class="anchor" id="autotoc_md34"></a>
Using PreparedStatement</h3>
<div class="fragment"><div class="line"><span class="keyword">auto</span>& pool = DatabaseManager::getAnalyticsPool();</div>
<div class="line"><span class="keyword">auto</span> con = pool.getConnection();</div>
<div class="line"> </div>
<div class="line"><span class="keyword">auto</span> stmt = con.prepareStatement(<span class="stringliteral">"INSERT INTO logs (message, timestamp) VALUES (?, ?)"</span>);</div>
<div class="line">stmt.bindValues(<span class="stringliteral">"User logged in"</span>, std::time(<span class="keyword">nullptr</span>));</div>
<div class="line">stmt.execute();</div>
</div><!-- fragment --><h3><a class="anchor" id="autotoc_md35"></a>
Transaction Example</h3>
<div class="fragment"><div class="line">Connection con = pool.getConnection();</div>
<div class="line"> </div>
<div class="line"><span class="comment">// Use default isolation level</span></div>
<div class="line">con.beginTransaction();</div>
<div class="line">con.execute(<span class="stringliteral">"UPDATE accounts SET balance = balance - ? WHERE id = ?"</span>, 100.0, 1);</div>
<div class="line">con.commit();</div>
<div class="line"> </div>
<div class="line"><span class="comment">// Alternatively, specify the transaction's isolation level</span></div>
<div class="line">con.beginTransaction(<a class="code hl_enumvalue" href="Connection_8h.html#a4cd1875ea5ecc896a0974c442afc2529a1d4194877393651107a4150e69a18178">TRANSACTION_SERIALIZABLE</a>));</div>
<div class="line">con.execute(<span class="stringliteral">"UPDATE accounts SET balance = balance + ? WHERE id = ?"</span>, 100.0, 2);</div>
<div class="line">con.commit();</div>
<div class="ttc" id="aConnection_8h_html_a4cd1875ea5ecc896a0974c442afc2529a1d4194877393651107a4150e69a18178"><div class="ttname"><a href="Connection_8h.html#a4cd1875ea5ecc896a0974c442afc2529a1d4194877393651107a4150e69a18178">TRANSACTION_SERIALIZABLE</a></div><div class="ttdeci">@ TRANSACTION_SERIALIZABLE</div><div class="ttdoc">Highest isolation level.</div><div class="ttdef"><b>Definition</b> Connection.h:181</div></div>
</div><!-- fragment --><h2><a class="anchor" id="autotoc_md36"></a>
Exception Handling</h2>
<p>All database-related errors are thrown as <code>sql_exception</code>, which derives from <code>std::runtime_error</code>.</p>
<h3><a class="anchor" id="autotoc_md37"></a>
Example of Exception Handling</h3>
<div class="fragment"><div class="line"><span class="keywordflow">try</span> {</div>
<div class="line"> Connection con = pool.getConnection();</div>
<div class="line"> con.beginTransaction();</div>
<div class="line"> con.execute(<span class="stringliteral">"UPDATE accounts SET balance = balance - ? WHERE id = ?"</span>, 100.0, 1);</div>
<div class="line"> con.execute(<span class="stringliteral">"UPDATE accounts SET balance = balance + ? WHERE id = ?"</span>, 100.0, 2);</div>
<div class="line"> con.commit();</div>
<div class="line"> std::cout << <span class="stringliteral">"Transfer successful"</span> << std::endl;</div>
<div class="line"> <span class="comment">// Connection is automatically returned to pool when it goes out of scope</span></div>
<div class="line"> <span class="comment">// If an exception occurred before commit, it will automatically rollback</span></div>
<div class="line">} <span class="keywordflow">catch</span> (<span class="keyword">const</span> sql_exception& e) {</div>
<div class="line"> std::cerr << <span class="stringliteral">"Transfer failed: "</span> << e.what() << std::endl;</div>
<div class="line">}</div>
</div><!-- fragment --><p> Key points about exception handling in this library:</p>
<ol type="1">
<li>All database operations that can fail will throw <code>sql_exception</code>.</li>
<li><code>sql_exception</code> provides informative error messages through its <code>what()</code> method.</li>
<li>You should wrap database operations in try-catch blocks to handle potential errors gracefully.</li>
<li>The library ensures that resources are properly managed even when exceptions are thrown, preventing resource leaks.</li>
</ol>
<dl class="section note"><dt>Note</dt><dd>For detailed API documentation, refer to the comments for each class in this header file. Visit <a href="https://www.tildeslash.com/libzdb/">libzdb's homepage</a> for additional documentation and examples. </dd></dl>
</div><table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a id="nested-classes" name="nested-classes"></a>
Data Structures</h2></td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">class  </td><td class="memItemRight" valign="bottom"><a class="el" href="classzdb_1_1sql__exception.html">sql_exception</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft"> </td><td class="mdescRight">Exception class for SQL related errors. <a href="classzdb_1_1sql__exception.html#details">More...</a><br /></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">class  </td><td class="memItemRight" valign="bottom"><a class="el" href="classzdb_1_1URL.html">URL</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft"> </td><td class="mdescRight">Represents an immutable Uniform Resource Locator. <a href="classzdb_1_1URL.html#details">More...</a><br /></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">class  </td><td class="memItemRight" valign="bottom"><a class="el" href="classzdb_1_1ResultSet.html">ResultSet</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft"> </td><td class="mdescRight">Represents a database result set. <a href="classzdb_1_1ResultSet.html#details">More...</a><br /></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">class  </td><td class="memItemRight" valign="bottom"><a class="el" href="classzdb_1_1PreparedStatement.html">PreparedStatement</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft"> </td><td class="mdescRight">Represents a pre-compiled SQL statement for later execution. <a href="classzdb_1_1PreparedStatement.html#details">More...</a><br /></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">class  </td><td class="memItemRight" valign="bottom"><a class="el" href="classzdb_1_1Connection.html">Connection</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft"> </td><td class="mdescRight">Represents a connection to a SQL database system. <a href="classzdb_1_1Connection.html#details">More...</a><br /></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">class  </td><td class="memItemRight" valign="bottom"><a class="el" href="classzdb_1_1ConnectionPool.html">ConnectionPool</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft"> </td><td class="mdescRight">Represents a database connection pool. <a href="classzdb_1_1ConnectionPool.html#details">More...</a><br /></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2"> </td></tr>
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Namespaces</h2></td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">namespace  </td><td class="memItemRight" valign="bottom"><a class="el" href="namespacezdb.html">zdb</a></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:"><td class="memItemLeft" align="right" valign="top">namespace  </td><td class="memItemRight" valign="bottom"><a class="el" href="namespacezdb_1_1version.html">zdb::version</a></td></tr>
<tr class="separator:"><td class="memSeparator" colspan="2"> </td></tr>
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Functions</h2></td></tr>
<tr class="memitem:af8486074fe6c80650a728860d3c4de60" id="r_af8486074fe6c80650a728860d3c4de60"><td class="memItemLeft" align="right" valign="top">constexpr bool </td><td class="memItemRight" valign="bottom"><a class="el" href="namespacezdb_1_1version.html#af8486074fe6c80650a728860d3c4de60">is_compatible_with</a> (int required_major, int required_minor, int required_revision=0)</td></tr>
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Variables</h2></td></tr>
<tr class="memitem:a066d8320116071c18c318137256c742c" id="r_a066d8320116071c18c318137256c742c"><td class="memItemLeft" align="right" valign="top">constexpr int </td><td class="memItemRight" valign="bottom"><a class="el" href="namespacezdb_1_1version.html#a066d8320116071c18c318137256c742c">major</a> = <a class="el" href="zdb_8h.html#ac2bd7a62e121fe9dc4d5789b6a2259ac">LIBZDB_MAJOR</a></td></tr>
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<tr class="memitem:a9dc4f35e724a7817f5e7ce8921ae355a" id="r_a9dc4f35e724a7817f5e7ce8921ae355a"><td class="memItemLeft" align="right" valign="top">constexpr int </td><td class="memItemRight" valign="bottom"><a class="el" href="namespacezdb_1_1version.html#a9dc4f35e724a7817f5e7ce8921ae355a">minor</a> = <a class="el" href="zdb_8h.html#aed91096d9e9dca098a33a67591b35d90">LIBZDB_MINOR</a></td></tr>
<tr class="separator:a9dc4f35e724a7817f5e7ce8921ae355a"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:a86b70547aa2cda23192e4a236b00e0c5" id="r_a86b70547aa2cda23192e4a236b00e0c5"><td class="memItemLeft" align="right" valign="top">constexpr int </td><td class="memItemRight" valign="bottom"><a class="el" href="namespacezdb_1_1version.html#a86b70547aa2cda23192e4a236b00e0c5">revision</a> = <a class="el" href="zdb_8h.html#a6ed34fa6fa44682aeb98bd514a3483e8">LIBZDB_REVISION</a></td></tr>
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<tr class="memitem:a302ff71256ab8b5a11d66ec2a37df03c" id="r_a302ff71256ab8b5a11d66ec2a37df03c"><td class="memItemLeft" align="right" valign="top">constexpr int </td><td class="memItemRight" valign="bottom"><a class="el" href="namespacezdb_1_1version.html#a302ff71256ab8b5a11d66ec2a37df03c">number</a> = <a class="el" href="zdb_8h.html#ad0666bcbb9d1a5fdb5b353d5e9404432">LIBZDB_VERSION_NUMBER</a></td></tr>
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<tr class="memitem:af77456ea4829e3d46f9b80817c7159e8" id="r_af77456ea4829e3d46f9b80817c7159e8"><td class="memItemLeft" align="right" valign="top">constexpr std::string_view </td><td class="memItemRight" valign="bottom"><a class="el" href="namespacezdb_1_1version.html#af77456ea4829e3d46f9b80817c7159e8">string</a> = <a class="el" href="zdb_8h.html#aa3db9b5d3124f26f601b2f77e1b7a09e">LIBZDB_VERSION</a></td></tr>
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