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<h2>SqlQuery</h2>
<p>
With SqlQuery we can execute sql queries without any entity beans or dto beans.
Instead we can:
</p>
<ul>
<li>Read JDBC <code>ResultSet</code> directly</li>
<li>Read as <code>SqlRow</code> objects</li>
<li>Use <code>mapToScalar()</code> and read simple scalar values like Long, BigDecimal, OffsetDateTime etc</li>
<li>use <code>mapTo()</code> and <code>RowMapper</code> to map and read objects</li>
</ul>
<p> </p>
<h5>Example findOne with SqlRow</h5>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select id, name, when_active from customer where id = :id"</span>
<span class="n">SqlRow</span> <span class="n">row</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="s">"id"</span><span class="o">,</span> <span class="mi">42</span><span class="o">)</span>
<span class="o">.</span><span class="na">findOne</span><span class="o">();</span>
<span class="n">String</span> <span class="n">name</span> <span class="o">=</span> <span class="n">row</span><span class="o">.</span><span class="na">getString</span><span class="o">(</span><span class="s">"name"</span><span class="o">);</span>
<span class="n">Timestamp</span> <span class="n">active</span> <span class="o">=</span> <span class="n">row</span><span class="o">.</span><span class="na">getTimestamp</span><span class="o">(</span><span class="s">"when_active"</span><span class="o">);</span>
</pre></div>
</div>
<p> </p>
<h5>Example findEachRow with ResultSet</h5>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select id, name, status from customer order by name desc"</span><span class="o">;</span>
<span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">findEachRow</span><span class="o">((</span><span class="n">resultSet</span><span class="o">,</span> <span class="n">rowNum</span><span class="o">)</span> <span class="o">-></span> <span class="o">{</span>
<span class="kt">long</span> <span class="n">id</span> <span class="o">=</span> <span class="n">resultSet</span><span class="o">.</span><span class="na">getLong</span><span class="o">(</span><span class="mi">1</span><span class="o">);</span>
<span class="n">String</span> <span class="n">name</span> <span class="o">=</span> <span class="n">resultSet</span><span class="o">.</span><span class="na">getString</span><span class="o">(</span><span class="mi">2</span><span class="o">);</span>
<span class="o">...</span>
<span class="o">});</span>
</pre></div>
</div>
<h5>Example mapToScalar()</h5>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select mysequence.nextval"</span><span class="o">;</span>
<span class="n">Long</span> <span class="n">nextVal</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">mapToScalar</span><span class="o">(</span><span class="n">Long</span><span class="o">.</span><span class="na">class</span><span class="o">)</span>
<span class="o">.</span><span class="na">findOne</span><span class="o">();</span>
</pre></div>
</div>
<h2 id="bind-positioned" class="art">Binding positioned parameters using ?</h2>
<p>
Positioned parameters use <code>?</code> as the placeholder.
</p>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select id, name, when_active from customer where status = ? and when_created > ?"</span><span class="o">;</span>
<span class="n">List</span><span class="o"><</span><span class="n">SqlRow</span><span class="o">></span> <span class="n">rows</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="mi">1</span><span class="o">,</span> <span class="s">"NEW"</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="mi">2</span><span class="o">,</span> <span class="n">lastWeek</span><span class="o">)</span>
<span class="o">.</span><span class="na">findList</span><span class="o">();</span>
</pre></div>
</div>
<p>
We can omit the index positions like the next example.
</p>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select id, name, when_active from customer where status = ? and when_created > ?"</span><span class="o">;</span>
<span class="n">List</span><span class="o"><</span><span class="n">SqlRow</span><span class="o">></span> <span class="n">rows</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="s">"NEW"</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="n">lastWeek</span><span class="o">)</span>
<span class="o">.</span><span class="na">findList</span><span class="o">();</span>
</pre></div>
</div>
<p>
We can alternatively set multiple positioned parameters using <code>setParameters()</code>.
</p>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select id, name, when_active from customer where status = ? and when_created > ?"</span><span class="o">;</span>
<span class="n">List</span><span class="o"><</span><span class="n">SqlRow</span><span class="o">></span> <span class="n">rows</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameters</span><span class="o">(</span><span class="s">"NEW"</span><span class="o">,</span> <span class="n">lastWeek</span><span class="o">)</span>
<span class="o">.</span><span class="na">findList</span><span class="o">();</span>
</pre></div>
</div>
<h2 id="bind-named" class="art">Binding named parameters using :name</h2>
<p>
Named parameters use the form <code>:foo</code> as the placeholder. Named parameters have the
advantages that we can use them to bind collections into an <code>IN</code> expression and
that the same parameter can appear multiple times in the SQL.
</p>
<h5>Binding using named parameters</h5>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span>
<span class="s">"select id, name, when_active "</span> <span class="o">+</span>
<span class="s">"from customer "</span> <span class="o">+</span>
<span class="s">"where status = :status and when_created > :created"</span><span class="o">;</span>
<span class="n">List</span><span class="o"><</span><span class="n">SqlRow</span><span class="o">></span> <span class="n">rows</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="s">"status"</span><span class="o">,</span> <span class="s">"NEW"</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="s">"created"</span><span class="o">,</span> <span class="n">lastWeek</span><span class="o">)</span>
<span class="o">.</span><span class="na">findList</span><span class="o">();</span>
</pre></div>
</div>
<h2 id="collections" class="art">Binding collections</h2>
<p>
To bind collections of values into an IN clause we need to used named parameters
or indexed positioned parameters.
</p>
<h5>Named parameter example (:names)</h5>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select c.id, c.name from customer c where c.name in (:names)"</span><span class="o">;</span>
<span class="n">List</span><span class="o"><</span><span class="n">SqlRow</span><span class="o">></span> <span class="n">rows</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="s">"names"</span><span class="o">,</span> <span class="n">asList</span><span class="o">(</span><span class="s">"Rob"</span><span class="o">,</span> <span class="s">"Fiona"</span><span class="o">,</span> <span class="s">"Jack"</span><span class="o">))</span>
<span class="o">.</span><span class="na">findList</span><span class="o">();</span>
</pre></div>
</div>
<h5>Index parameter example - ?2</h5>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select c.id, c.name from customer c "</span> <span class="o">+</span>
<span class="s">"where c.status = ? and c.name in (?2) and c.when_created > ?"</span><span class="o">;</span>
<span class="n">List</span><span class="o"><</span><span class="n">SqlRow</span><span class="o">></span> <span class="n">rows</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="s">"NEW"</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="n">asList</span><span class="o">(</span><span class="s">"Rob"</span><span class="o">,</span> <span class="s">"Fiona"</span><span class="o">,</span> <span class="s">"Jack"</span><span class="o">))</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="n">lastWeek</span><span class="o">)</span>
<span class="o">.</span><span class="na">findList</span><span class="o">();</span>
</pre></div>
</div>
<h2 id="any" class="art">Postgres ANY</h2>
<p>
When using Postgres we can use Postgres <code>ANY</code> in SqlQuery with positioned parameters.
</p>
<p>
The benefit of using Postgres <code>ANY</code> is that we end up using a single SQL query regardless of the number
of parameters - a single JDBC PreparedStatement and the database has a single SQL query to parse. This results in
the database doing less hard parsing and better use of PreparedStatement cache, less query plans to cache, less memory consumed.
</p>
<h5>Example</h5>
<p>
When using index positioned parameters and binding a collection that will bind as a JDBC ARRAY.
</p>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">List</span><span class="o"><</span><span class="n">Integer</span><span class="o">></span> <span class="n">ids</span> <span class="o">=</span> <span class="n">List</span><span class="o">.</span><span class="na">of</span><span class="o">(</span><span class="mi">1</span><span class="o">,</span> <span class="mi">2</span><span class="o">);</span>
<span class="n">List</span><span class="o"><</span><span class="n">SqlRow</span><span class="o">></span> <span class="n">list</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="s">"select id, name from o_customer where id = any(?)"</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="mi">1</span><span class="o">,</span> <span class="n">ids</span><span class="o">)</span> <span class="c1">// bind as JDBC ARRAY</span>
<span class="o">.</span><span class="na">findList</span><span class="o">();</span>
</pre></div>
</div>
<p>
When using Postgres we would often prefer to use that over using an <code>IN</code> clause
like the example below. The reason we prefer <code>ANY</code> is that it does not matter how
many elements we have in the ARRAY we end up with a single SQL statement. This gives us a single
query plan, single PrepareStatement and on the database end a single query statement to parse regardless
of the number of id values we are binding.
</p>
<p>
In comparison to using an <code>IN</code> clause, if we have 3 ids that is a different SQL query to one
that has 4 ids for example - we end up with more distinct PreparedStatements, potentially a lot more depending
on the number of id values we have.
</p>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">List</span><span class="o"><</span><span class="n">SqlRow</span><span class="o">></span> <span class="n">list</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="s">"select id, name from o_customer where id in (:idList)"</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="s">"idList"</span><span class="o">,</span> <span class="n">ids</span><span class="o">)</span> <span class="c1">// bind parameter expansion</span>
<span class="o">.</span><span class="na">findList</span><span class="o">();</span>
</pre></div>
</div>
<p>
Using the <code>IN</code> clause will result in a different SQL query when we have different numbers of
id values. With 4 id values supplied then <code>in (:idList)</code> is turned into SQL <code>in (?, ?, ?, ?)</code>.
</p>
<h2 id="limit" class="art">firstRow / maxRows</h2>
<p>
We can specify <em>firstRow</em> and <em>maxRows</em> on a SqlQuery and Ebean will modify
the SQL based on the database platform to add the appropriate row limit clause.
</p>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select id, name, when_active from customer where status = ?"</span><span class="o">;</span>
<span class="n">List</span><span class="o"><</span><span class="n">SqlRow</span><span class="o">></span> <span class="n">rows</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="mi">1</span><span class="o">,</span> <span class="s">"NEW"</span><span class="o">)</span>
<span class="o">.</span><span class="na">setFirstRow</span><span class="o">(</span><span class="mi">10</span><span class="o">)</span>
<span class="o">.</span><span class="na">setMaxRows</span><span class="o">(</span><span class="mi">10</span><span class="o">)</span>
<span class="o">.</span><span class="na">findList</span><span class="o">();</span>
</pre></div>
</div>
<h2 id="scalar" class="art">mapToScalar() - single column scalar result</h2>
<p>
Use <code>mapToScalar()</code> when the query has a single column in the <em>select clause</em>.
This specifies the type to use to read the result.
</p>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select mysequence.nextval"</span><span class="o">;</span>
<span class="n">Long</span> <span class="n">nextVal</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">mapToScalar</span><span class="o">(</span><span class="n">Long</span><span class="o">.</span><span class="na">class</span><span class="o">)</span>
<span class="o">.</span><span class="na">findOne</span><span class="o">();</span>
</pre></div>
</div>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select max(unit_price) from order_lines where order_qty > ?"</span><span class="o">;</span>
<span class="n">BigDecimal</span> <span class="n">maxPrice</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="mi">42</span><span class="o">)</span>
<span class="o">.</span><span class="na">mapToScalar</span><span class="o">(</span><span class="n">BigDecimal</span><span class="o">.</span><span class="na">class</span><span class="o">)</span>
<span class="o">.</span><span class="na">findOne</span><span class="o">();</span>
</pre></div>
</div>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select max(order_date) from orders where customer_id = ?"</span><span class="o">;</span>
<span class="n">OffsetDateTime</span> <span class="n">maxDate</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="mi">42</span><span class="o">)</span>
<span class="o">.</span><span class="na">mapToScalar</span><span class="o">(</span><span class="n">OffsetDateTime</span><span class="o">.</span><span class="na">class</span><span class="o">)</span>
<span class="o">.</span><span class="na">findOne</span><span class="o">();</span>
</pre></div>
</div>
<p>
All scalar types that Ebean supports can be used - refer to <a href="/docs/mapping/type/">mapping types</a>.
</p>
<h2 id="rowmapper" class="art">mapTo() - RowMapper</h2>
<p>
We can implement a <em>RowMapper</em> to convert a ResultSet into a dto bean.
</p>
<p>
Note that this similar to <a href="dtoquery">DtoQuery</a> except that the mapping is here is explicit
and with DtoQuery the mapping is effectively automatic (no effort) based on naming convention mapping.
In that sense the expectation is that people will use DtoQuery first and only use this explicit
RowMapping when necessary.
</p>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="kd">static</span> <span class="kd">class</span> <span class="nc">CustomerDtoMapper</span> <span class="kd">implements</span> <span class="n">RowMapper</span><span class="o"><</span><span class="n">CustomerDto</span><span class="o">></span> <span class="o">{</span>
<span class="nd">@Override</span>
<span class="kd">public</span> <span class="n">CustomerDto</span> <span class="nf">map</span><span class="o">(</span><span class="n">ResultSet</span> <span class="n">resultSet</span><span class="o">,</span> <span class="kt">int</span> <span class="n">rowNum</span><span class="o">)</span> <span class="kd">throws</span> <span class="n">SQLException</span> <span class="o">{</span>
<span class="kt">long</span> <span class="n">id</span> <span class="o">=</span> <span class="n">resultSet</span><span class="o">.</span><span class="na">getLong</span><span class="o">(</span><span class="mi">1</span><span class="o">);</span>
<span class="n">String</span> <span class="n">name</span> <span class="o">=</span> <span class="n">resultSet</span><span class="o">.</span><span class="na">getString</span><span class="o">(</span><span class="mi">2</span><span class="o">);</span>
<span class="n">String</span> <span class="n">status</span> <span class="o">=</span> <span class="n">resultSet</span><span class="o">.</span><span class="na">getString</span><span class="o">(</span><span class="mi">3</span><span class="o">);</span>
<span class="k">return</span> <span class="k">new</span> <span class="n">CustomerDto</span><span class="o">(</span><span class="n">id</span><span class="o">,</span> <span class="n">name</span><span class="o">,</span> <span class="n">status</span><span class="o">);</span>
<span class="o">}</span>
<span class="o">}</span>
<span class="o">...</span>
<span class="kd">static</span> <span class="kd">final</span> <span class="n">CustomerDtoMapper</span> <span class="n">CUSTOMER_MAPPER</span> <span class="o">=</span> <span class="k">new</span> <span class="n">CustomerDtoMapper</span><span class="o">()</span>
</pre></div>
</div>
<p> </p>
<p>
Then we can use it to return DTO beans.
</p>
<div class="syntax java"><div class="highlight"><pre><span></span><span class="n">String</span> <span class="n">sql</span> <span class="o">=</span> <span class="s">"select id, name, status from customer where name = ?"</span><span class="o">;</span>
<span class="n">List</span><span class="o"><</span><span class="n">CustomerDto</span><span class="o">></span> <span class="n">rob</span> <span class="o">=</span> <span class="n">DB</span><span class="o">.</span><span class="na">sqlQuery</span><span class="o">(</span><span class="n">sql</span><span class="o">)</span>
<span class="o">.</span><span class="na">setParameter</span><span class="o">(</span><span class="s">"Rob"</span><span class="o">)</span>
<span class="o">.</span><span class="na">mapTo</span><span class="o">(</span><span class="n">CUSTOMER_MAPPER</span><span class="o">)</span>
<span class="o">.</span><span class="na">findList</span><span class="o">();</span>
</pre></div>
</div>
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