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<h1 class="title">DESCRIBE QUERY</h1>
<h3 id="description">Description</h3>
<p>The <code class="highlighter-rouge">DESCRIBE QUERY</code> statement is used to return the metadata of output
of a query. A shorthand <code class="highlighter-rouge">DESC</code> may be used instead of <code class="highlighter-rouge">DESCRIBE</code> to
describe the query output.</p>
<h3 id="syntax">Syntax</h3>
<figure class="highlight"><pre><code class="language-sql" data-lang="sql"><span class="err">{</span> <span class="k">DESC</span> <span class="o">|</span> <span class="k">DESCRIBE</span> <span class="err">}</span> <span class="p">[</span> <span class="n">QUERY</span> <span class="p">]</span> <span class="n">input_statement</span></code></pre></figure>
<h3 id="parameters">Parameters</h3>
<dl>
<dt><code><em>QUERY</em></code></dt>
<dd>This clause is optional and may be omitted.</dd>
<dt><code><em>input_statement</em></code></dt>
<dd>
Specifies a result set producing statement and may be one of the following:
<ul>
<li>a <code>SELECT</code> statement</li>
<li>a <code>CTE(Common table expression)</code> statement</li>
<li>an <code>INLINE TABLE</code> statement</li>
<li>a <code>TABLE</code> statement</li>
<li>a <code>FROM</code> statement</li>
</ul>
Please refer to <a href="sql-ref-syntax-qry-select.html">select-statement</a>
for a detailed syntax of the query parameter.
</dd>
</dl>
<h3 id="examples">Examples</h3>
<figure class="highlight"><pre><code class="language-sql" data-lang="sql"><span class="c1">-- Create table `person`</span>
<span class="k">CREATE</span> <span class="k">TABLE</span> <span class="n">person</span> <span class="p">(</span><span class="n">name</span> <span class="n">STRING</span> <span class="p">,</span> <span class="n">age</span> <span class="nb">INT</span> <span class="k">COMMENT</span> <span class="s1">'Age column'</span><span class="p">,</span> <span class="n">address</span> <span class="n">STRING</span><span class="p">);</span>
<span class="c1">-- Returns column metadata information for a simple select query</span>
<span class="k">DESCRIBE</span> <span class="n">QUERY</span> <span class="k">select</span> <span class="n">age</span><span class="p">,</span> <span class="k">sum</span><span class="p">(</span><span class="n">age</span><span class="p">)</span> <span class="k">FROM</span> <span class="n">person</span> <span class="k">GROUP</span> <span class="k">BY</span> <span class="n">age</span><span class="p">;</span>
<span class="o">+</span><span class="c1">--------+---------+----------+</span>
<span class="o">|</span><span class="n">col_name</span><span class="o">|</span><span class="n">data_type</span><span class="o">|</span><span class="k">comment</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">--------+---------+----------+</span>
<span class="o">|</span><span class="n">age</span> <span class="o">|</span><span class="nb">int</span> <span class="o">|</span><span class="n">Age</span> <span class="k">column</span><span class="o">|</span>
<span class="o">|</span><span class="k">sum</span><span class="p">(</span><span class="n">age</span><span class="p">)</span><span class="o">|</span><span class="nb">bigint</span> <span class="o">|</span><span class="k">null</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">--------+---------+----------+</span>
<span class="c1">-- Returns column metadata information for common table expression (`CTE`).</span>
<span class="k">DESCRIBE</span> <span class="n">QUERY</span> <span class="k">WITH</span> <span class="n">all_names_cte</span>
<span class="k">AS</span> <span class="p">(</span><span class="k">SELECT</span> <span class="n">name</span> <span class="k">from</span> <span class="n">person</span><span class="p">)</span> <span class="k">SELECT</span> <span class="o">*</span> <span class="k">FROM</span> <span class="n">all_names_cte</span><span class="p">;</span>
<span class="o">+</span><span class="c1">--------+---------+-------+</span>
<span class="o">|</span><span class="n">col_name</span><span class="o">|</span><span class="n">data_type</span><span class="o">|</span><span class="k">comment</span><span class="o">|</span>
<span class="o">+</span><span class="c1">--------+---------+-------+</span>
<span class="o">|</span><span class="n">name</span> <span class="o">|</span><span class="n">string</span> <span class="o">|</span><span class="k">null</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">--------+---------+-------+</span>
<span class="c1">-- Returns column metadata information for a inline table.</span>
<span class="k">DESC</span> <span class="n">QUERY</span> <span class="k">VALUES</span><span class="p">(</span><span class="mi">100</span><span class="p">,</span> <span class="s1">'John'</span><span class="p">,</span> <span class="mi">10000</span><span class="p">.</span><span class="mi">20</span><span class="n">D</span><span class="p">)</span> <span class="k">AS</span> <span class="n">employee</span><span class="p">(</span><span class="n">id</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">salary</span><span class="p">);</span>
<span class="o">+</span><span class="c1">--------+---------+-------+</span>
<span class="o">|</span><span class="n">col_name</span><span class="o">|</span><span class="n">data_type</span><span class="o">|</span><span class="k">comment</span><span class="o">|</span>
<span class="o">+</span><span class="c1">--------+---------+-------+</span>
<span class="o">|</span><span class="n">id</span> <span class="o">|</span><span class="nb">int</span> <span class="o">|</span><span class="k">null</span> <span class="o">|</span>
<span class="o">|</span><span class="n">name</span> <span class="o">|</span><span class="n">string</span> <span class="o">|</span><span class="k">null</span> <span class="o">|</span>
<span class="o">|</span><span class="n">salary</span> <span class="o">|</span><span class="nb">double</span> <span class="o">|</span><span class="k">null</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">--------+---------+-------+</span>
<span class="c1">-- Returns column metadata information for `TABLE` statement.</span>
<span class="k">DESC</span> <span class="n">QUERY</span> <span class="k">TABLE</span> <span class="n">person</span><span class="p">;</span>
<span class="o">+</span><span class="c1">--------+---------+----------+</span>
<span class="o">|</span><span class="n">col_name</span><span class="o">|</span><span class="n">data_type</span><span class="o">|</span><span class="k">comment</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">--------+---------+----------+</span>
<span class="o">|</span><span class="n">name</span> <span class="o">|</span><span class="n">string</span> <span class="o">|</span><span class="k">null</span> <span class="o">|</span>
<span class="o">|</span><span class="n">age</span> <span class="o">|</span><span class="nb">int</span> <span class="o">|</span><span class="n">Age</span> <span class="k">column</span><span class="o">|</span>
<span class="o">|</span><span class="n">address</span> <span class="o">|</span><span class="n">string</span> <span class="o">|</span><span class="k">null</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">--------+---------+----------+</span>
<span class="c1">-- Returns column metadata information for a `FROM` statement.</span>
<span class="c1">-- `QUERY` clause is optional and can be omitted.</span>
<span class="k">DESCRIBE</span> <span class="k">FROM</span> <span class="n">person</span> <span class="k">SELECT</span> <span class="n">age</span><span class="p">;</span>
<span class="o">+</span><span class="c1">--------+---------+----------+</span>
<span class="o">|</span><span class="n">col_name</span><span class="o">|</span><span class="n">data_type</span><span class="o">|</span><span class="k">comment</span> <span class="o">|</span>
<span class="o">+</span><span class="c1">--------+---------+----------+</span>
<span class="o">|</span><span class="n">age</span> <span class="o">|</span><span class="nb">int</span> <span class="o">|</span><span class="n">Age</span> <span class="k">column</span><span class="o">|</span>
<span class="o">+</span><span class="c1">--------+---------+----------+</span></code></pre></figure>
<h3 id="related-statements">Related Statements</h3>
<ul>
<li><a href="sql-ref-syntax-aux-describe-database.html">DESCRIBE DATABASE</a></li>
<li><a href="sql-ref-syntax-aux-describe-table.html">DESCRIBE TABLE</a></li>
<li><a href="sql-ref-syntax-aux-describe-function.html">DESCRIBE FUNCTION</a></li>
</ul>
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