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<div class="section" id="module-psycopg2.sql">
<span id="psycopg2-sql-sql-string-composition"></span><h1><a class="reference internal" href="#module-psycopg2.sql" title="psycopg2.sql"><code class="xref py py-obj docutils literal"><span class="pre">psycopg2.sql</span></code></a> – SQL string composition<a class="headerlink" href="#module-psycopg2.sql" title="Permalink to this headline">¶</a></h1>
<div class="versionadded">
<p><span class="versionmodified">New in version 2.7.</span></p>
</div>
<p>The module contains objects and functions useful to generate SQL dynamically,
in a convenient and safe way. SQL identifiers (e.g. names of tables and
fields) cannot be passed to the <a class="reference internal" href="cursor.html#cursor.execute" title="cursor.execute"><code class="xref py py-obj docutils literal"><span class="pre">execute()</span></code></a> method like query
arguments:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="c1"># This will not work</span>
<span class="n">table_name</span> <span class="o">=</span> <span class="s1">'my_table'</span>
<span class="n">cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="s2">"insert into </span><span class="si">%s</span><span class="s2"> values (</span><span class="si">%s</span><span class="s2">, </span><span class="si">%s</span><span class="s2">)"</span><span class="p">,</span> <span class="p">[</span><span class="n">table_name</span><span class="p">,</span> <span class="mi">10</span><span class="p">,</span> <span class="mi">20</span><span class="p">])</span>
</pre></div>
</div>
<p>The SQL query should be composed before the arguments are merged, for
instance:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="c1"># This works, but it is not optimal</span>
<span class="n">table_name</span> <span class="o">=</span> <span class="s1">'my_table'</span>
<span class="n">cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span>
<span class="s2">"insert into </span><span class="si">%s</span><span class="s2"> values (</span><span class="si">%%</span><span class="s2">s, </span><span class="si">%%</span><span class="s2">s)"</span> <span class="o">%</span> <span class="n">table_name</span><span class="p">,</span>
<span class="p">[</span><span class="mi">10</span><span class="p">,</span> <span class="mi">20</span><span class="p">])</span>
</pre></div>
</div>
<p>This sort of works, but it is an accident waiting to happen: the table name
may be an invalid SQL literal and need quoting; even more serious is the
security problem in case the table name comes from an untrusted source. The
name should be escaped using <a class="reference internal" href="extensions.html#psycopg2.extensions.quote_ident" title="psycopg2.extensions.quote_ident"><code class="xref py py-obj docutils literal"><span class="pre">quote_ident()</span></code></a>:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="c1"># This works, but it is not optimal</span>
<span class="n">table_name</span> <span class="o">=</span> <span class="s1">'my_table'</span>
<span class="n">cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span>
<span class="s2">"insert into </span><span class="si">%s</span><span class="s2"> values (</span><span class="si">%%</span><span class="s2">s, </span><span class="si">%%</span><span class="s2">s)"</span> <span class="o">%</span> <span class="n">ext</span><span class="o">.</span><span class="n">quote_ident</span><span class="p">(</span><span class="n">table_name</span><span class="p">),</span>
<span class="p">[</span><span class="mi">10</span><span class="p">,</span> <span class="mi">20</span><span class="p">])</span>
</pre></div>
</div>
<p>This is now safe, but it somewhat ad-hoc. In case, for some reason, it is
necessary to include a value in the query string (as opposite as in a value)
the merging rule is still different (<a class="reference internal" href="extensions.html#psycopg2.extensions.adapt" title="psycopg2.extensions.adapt"><code class="xref py py-obj docutils literal"><span class="pre">adapt()</span></code></a> should be
used…). It is also still relatively dangerous: if <code class="xref py py-obj docutils literal"><span class="pre">quote_ident()</span></code> is
forgotten somewhere, the program will usually work, but will eventually crash
in the presence of a table or field name with containing characters to escape,
or will present a potentially exploitable weakness.</p>
<p>The objects exposed by the <code class="xref py py-obj docutils literal"><span class="pre">psycopg2.sql</span></code> module allow generating SQL
statements on the fly, separating clearly the variable parts of the statement
from the query parameters:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">psycopg2</span> <span class="kn">import</span> <span class="n">sql</span>
<span class="n">cur</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span>
<span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s2">"insert into {} values (</span><span class="si">%s</span><span class="s2">, </span><span class="si">%s</span><span class="s2">)"</span><span class="p">)</span>
<span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s1">'my_table'</span><span class="p">)),</span>
<span class="p">[</span><span class="mi">10</span><span class="p">,</span> <span class="mi">20</span><span class="p">])</span>
</pre></div>
</div>
<p>The objects exposed by the <code class="xref py py-obj docutils literal"><span class="pre">sql</span></code> module can be used to compose a query as a
Python string (using the <a class="reference internal" href="#psycopg2.sql.Composable.as_string" title="psycopg2.sql.Composable.as_string"><code class="xref py py-obj docutils literal"><span class="pre">as_string()</span></code></a> method) or passed directly
to cursor methods such as <a class="reference internal" href="cursor.html#cursor.execute" title="cursor.execute"><code class="xref py py-obj docutils literal"><span class="pre">execute()</span></code></a>, <a class="reference internal" href="cursor.html#cursor.executemany" title="cursor.executemany"><code class="xref py py-obj docutils literal"><span class="pre">executemany()</span></code></a>,
<a class="reference internal" href="cursor.html#cursor.copy_expert" title="cursor.copy_expert"><code class="xref py py-obj docutils literal"><span class="pre">copy_expert()</span></code></a>.</p>
<dl class="class">
<dt id="psycopg2.sql.Composable">
<em class="property">class </em><code class="descclassname">psycopg2.sql.</code><code class="descname">Composable</code><span class="sig-paren">(</span><em>wrapped</em><span class="sig-paren">)</span><a class="headerlink" href="#psycopg2.sql.Composable" title="Permalink to this definition">¶</a></dt>
<dd><p>Abstract base class for objects that can be used to compose an SQL string.</p>
<p><code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code> objects can be passed directly to <a class="reference internal" href="cursor.html#cursor.execute" title="cursor.execute"><code class="xref py py-obj docutils literal"><span class="pre">execute()</span></code></a>,
<a class="reference internal" href="cursor.html#cursor.executemany" title="cursor.executemany"><code class="xref py py-obj docutils literal"><span class="pre">executemany()</span></code></a>, <a class="reference internal" href="cursor.html#cursor.copy_expert" title="cursor.copy_expert"><code class="xref py py-obj docutils literal"><span class="pre">copy_expert()</span></code></a> in place of the query
string.</p>
<p><code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code> objects can be joined using the <code class="docutils literal"><span class="pre">+</span></code> operator: the result
will be a <a class="reference internal" href="#psycopg2.sql.Composed" title="psycopg2.sql.Composed"><code class="xref py py-obj docutils literal"><span class="pre">Composed</span></code></a> instance containing the objects joined. The operator
<code class="docutils literal"><span class="pre">*</span></code> is also supported with an integer argument: the result is a
<code class="xref py py-obj docutils literal"><span class="pre">Composed</span></code> instance containing the left argument repeated as many times as
requested.</p>
<dl class="method">
<dt id="psycopg2.sql.Composable.as_string">
<code class="descname">as_string</code><span class="sig-paren">(</span><em>context</em><span class="sig-paren">)</span><a class="headerlink" href="#psycopg2.sql.Composable.as_string" title="Permalink to this definition">¶</a></dt>
<dd><p>Return the string value of the object.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>context</strong> (<a class="reference internal" href="connection.html#connection" title="connection"><code class="xref py py-obj docutils literal"><span class="pre">connection</span></code></a> or <a class="reference internal" href="cursor.html#cursor" title="cursor"><code class="xref py py-obj docutils literal"><span class="pre">cursor</span></code></a>) – the context to evaluate the string into.</td>
</tr>
</tbody>
</table>
<p>The method is automatically invoked by <a class="reference internal" href="cursor.html#cursor.execute" title="cursor.execute"><code class="xref py py-obj docutils literal"><span class="pre">execute()</span></code></a>,
<a class="reference internal" href="cursor.html#cursor.executemany" title="cursor.executemany"><code class="xref py py-obj docutils literal"><span class="pre">executemany()</span></code></a>, <a class="reference internal" href="cursor.html#cursor.copy_expert" title="cursor.copy_expert"><code class="xref py py-obj docutils literal"><span class="pre">copy_expert()</span></code></a> if a <code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code> is
passed instead of the query string.</p>
</dd></dl>
</dd></dl>
<dl class="class">
<dt id="psycopg2.sql.SQL">
<em class="property">class </em><code class="descclassname">psycopg2.sql.</code><code class="descname">SQL</code><span class="sig-paren">(</span><em>string</em><span class="sig-paren">)</span><a class="headerlink" href="#psycopg2.sql.SQL" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference internal" href="#psycopg2.sql.Composable" title="psycopg2.sql.Composable"><code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code></a> representing a snippet of SQL statement.</p>
<p><code class="xref py py-obj docutils literal"><span class="pre">SQL</span></code> exposes <a class="reference internal" href="#psycopg2.sql.SQL.join" title="psycopg2.sql.SQL.join"><code class="xref py py-obj docutils literal"><span class="pre">join()</span></code></a> and <a class="reference internal" href="#psycopg2.sql.SQL.format" title="psycopg2.sql.SQL.format"><code class="xref py py-obj docutils literal"><span class="pre">format()</span></code></a> methods useful to create a template
where to merge variable parts of a query (for instance field or table
names).</p>
<p>The <em>string</em> doesn’t undergo any form of escaping, so it is not suitable to
represent variable identifiers or values: you should only use it to pass
constant strings representing templates or snippets of SQL statements; use
other objects such as <a class="reference internal" href="#psycopg2.sql.Identifier" title="psycopg2.sql.Identifier"><code class="xref py py-obj docutils literal"><span class="pre">Identifier</span></code></a> or <a class="reference internal" href="#psycopg2.sql.Literal" title="psycopg2.sql.Literal"><code class="xref py py-obj docutils literal"><span class="pre">Literal</span></code></a> to represent variable
parts.</p>
<p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">query</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s2">"select {0} from {1}"</span><span class="p">)</span><span class="o">.</span><span class="n">format</span><span class="p">(</span>
<span class="gp">... </span> <span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s1">', '</span><span class="p">)</span><span class="o">.</span><span class="n">join</span><span class="p">([</span><span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s1">'foo'</span><span class="p">),</span> <span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s1">'bar'</span><span class="p">)]),</span>
<span class="gp">... </span> <span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s1">'table'</span><span class="p">))</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="n">query</span><span class="o">.</span><span class="n">as_string</span><span class="p">(</span><span class="n">conn</span><span class="p">))</span>
<span class="go">select "foo", "bar" from "table"</span>
</pre></div>
</div>
<dl class="attribute">
<dt id="psycopg2.sql.SQL.string">
<code class="descname">string</code><a class="headerlink" href="#psycopg2.sql.SQL.string" title="Permalink to this definition">¶</a></dt>
<dd><p>The string wrapped by the <code class="xref py py-obj docutils literal"><span class="pre">SQL</span></code> object.</p>
</dd></dl>
<dl class="method">
<dt id="psycopg2.sql.SQL.format">
<code class="descname">format</code><span class="sig-paren">(</span><em>*args</em>, <em>**kwargs</em><span class="sig-paren">)</span><a class="headerlink" href="#psycopg2.sql.SQL.format" title="Permalink to this definition">¶</a></dt>
<dd><p>Merge <a class="reference internal" href="#psycopg2.sql.Composable" title="psycopg2.sql.Composable"><code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code></a> objects into a template.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>args</strong> (<a class="reference internal" href="#psycopg2.sql.Composable" title="psycopg2.sql.Composable"><em>Composable</em></a>) – parameters to replace to numbered
(<code class="docutils literal"><span class="pre">{0}</span></code>, <code class="docutils literal"><span class="pre">{1}</span></code>) or auto-numbered (<code class="docutils literal"><span class="pre">{}</span></code>) placeholders</li>
<li><strong>kwargs</strong> (<a class="reference internal" href="#psycopg2.sql.Composable" title="psycopg2.sql.Composable"><em>Composable</em></a>) – parameters to replace to named (<code class="docutils literal"><span class="pre">{name}</span></code>)
placeholders</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">the union of the <code class="xref py py-obj docutils literal"><span class="pre">SQL</span></code> string with placeholders replaced</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last"><a class="reference internal" href="#psycopg2.sql.Composed" title="psycopg2.sql.Composed"><code class="xref py py-obj docutils literal"><span class="pre">Composed</span></code></a></p>
</td>
</tr>
</tbody>
</table>
<p>The method is similar to the Python <code class="xref py py-obj docutils literal"><span class="pre">str.format()</span></code> method: the string
template supports auto-numbered (<code class="docutils literal"><span class="pre">{}</span></code>, only available from Python
2.7), numbered (<code class="docutils literal"><span class="pre">{0}</span></code>, <code class="docutils literal"><span class="pre">{1}</span></code>…), and named placeholders
(<code class="docutils literal"><span class="pre">{name}</span></code>), with positional arguments replacing the numbered
placeholders and keywords replacing the named ones. However placeholder
modifiers (<code class="docutils literal"><span class="pre">{0!r}</span></code>, <code class="docutils literal"><span class="pre">{0:<10}</span></code>) are not supported. Only
<code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code> objects can be passed to the template.</p>
<p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s2">"select * from {} where {} = </span><span class="si">%s</span><span class="s2">"</span><span class="p">)</span>
<span class="gp">... </span> <span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s1">'people'</span><span class="p">),</span> <span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s1">'id'</span><span class="p">))</span>
<span class="gp">... </span> <span class="o">.</span><span class="n">as_string</span><span class="p">(</span><span class="n">conn</span><span class="p">))</span>
<span class="go">select * from "people" where "id" = %s</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s2">"select * from {tbl} where {pkey} = </span><span class="si">%s</span><span class="s2">"</span><span class="p">)</span>
<span class="gp">... </span> <span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">tbl</span><span class="o">=</span><span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s1">'people'</span><span class="p">),</span> <span class="n">pkey</span><span class="o">=</span><span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s1">'id'</span><span class="p">))</span>
<span class="gp">... </span> <span class="o">.</span><span class="n">as_string</span><span class="p">(</span><span class="n">conn</span><span class="p">))</span>
<span class="go">select * from "people" where "id" = %s</span>
</pre></div>
</div>
</dd></dl>
<dl class="method">
<dt id="psycopg2.sql.SQL.join">
<code class="descname">join</code><span class="sig-paren">(</span><em>seq</em><span class="sig-paren">)</span><a class="headerlink" href="#psycopg2.sql.SQL.join" title="Permalink to this definition">¶</a></dt>
<dd><p>Join a sequence of <a class="reference internal" href="#psycopg2.sql.Composable" title="psycopg2.sql.Composable"><code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code></a>.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>seq</strong> (iterable of <code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code>) – the elements to join.</td>
</tr>
</tbody>
</table>
<p>Use the <code class="xref py py-obj docutils literal"><span class="pre">SQL</span></code> object’s <em>string</em> to separate the elements in <em>seq</em>.
Note that <a class="reference internal" href="#psycopg2.sql.Composed" title="psycopg2.sql.Composed"><code class="xref py py-obj docutils literal"><span class="pre">Composed</span></code></a> objects are iterable too, so they can be used as
argument for this method.</p>
<p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">snip</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s1">', '</span><span class="p">)</span><span class="o">.</span><span class="n">join</span><span class="p">(</span>
<span class="gp">... </span> <span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="n">n</span><span class="p">)</span> <span class="k">for</span> <span class="n">n</span> <span class="ow">in</span> <span class="p">[</span><span class="s1">'foo'</span><span class="p">,</span> <span class="s1">'bar'</span><span class="p">,</span> <span class="s1">'baz'</span><span class="p">])</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="n">snip</span><span class="o">.</span><span class="n">as_string</span><span class="p">(</span><span class="n">conn</span><span class="p">))</span>
<span class="go">"foo", "bar", "baz"</span>
</pre></div>
</div>
</dd></dl>
</dd></dl>
<dl class="class">
<dt id="psycopg2.sql.Identifier">
<em class="property">class </em><code class="descclassname">psycopg2.sql.</code><code class="descname">Identifier</code><span class="sig-paren">(</span><em>string</em><span class="sig-paren">)</span><a class="headerlink" href="#psycopg2.sql.Identifier" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference internal" href="#psycopg2.sql.Composable" title="psycopg2.sql.Composable"><code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code></a> representing an SQL identifer.</p>
<p>Identifiers usually represent names of database objects, such as tables or
fields. PostgreSQL identifiers follow <a class="reference external" href="https://www.postgresql.org/docs/current/static/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS">different rules</a> than SQL string
literals for escaping (e.g. they use double quotes instead of single).</p>
<p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">t1</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s2">"foo"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">t2</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s2">"ba'r"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">t3</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s1">'ba"z'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s1">', '</span><span class="p">)</span><span class="o">.</span><span class="n">join</span><span class="p">([</span><span class="n">t1</span><span class="p">,</span> <span class="n">t2</span><span class="p">,</span> <span class="n">t3</span><span class="p">])</span><span class="o">.</span><span class="n">as_string</span><span class="p">(</span><span class="n">conn</span><span class="p">))</span>
<span class="go">"foo", "ba'r", "ba""z"</span>
</pre></div>
</div>
<dl class="attribute">
<dt id="psycopg2.sql.Identifier.string">
<code class="descname">string</code><a class="headerlink" href="#psycopg2.sql.Identifier.string" title="Permalink to this definition">¶</a></dt>
<dd><p>The string wrapped by the <a class="reference internal" href="#psycopg2.sql.Identifier" title="psycopg2.sql.Identifier"><code class="xref py py-obj docutils literal"><span class="pre">Identifier</span></code></a>.</p>
</dd></dl>
</dd></dl>
<dl class="class">
<dt id="psycopg2.sql.Literal">
<em class="property">class </em><code class="descclassname">psycopg2.sql.</code><code class="descname">Literal</code><span class="sig-paren">(</span><em>wrapped</em><span class="sig-paren">)</span><a class="headerlink" href="#psycopg2.sql.Literal" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference internal" href="#psycopg2.sql.Composable" title="psycopg2.sql.Composable"><code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code></a> representing an SQL value to include in a query.</p>
<p>Usually you will want to include placeholders in the query and pass values
as <a class="reference internal" href="cursor.html#cursor.execute" title="cursor.execute"><code class="xref py py-obj docutils literal"><span class="pre">execute()</span></code></a> arguments. If however you really really need to
include a literal value in the query you can use this object.</p>
<p>The string returned by <code class="xref py py-obj docutils literal"><span class="pre">as_string()</span></code> follows the normal <a class="reference internal" href="usage.html#python-types-adaptation"><span class="std std-ref">adaptation
rules</span></a> for Python objects.</p>
<p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">s1</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">Literal</span><span class="p">(</span><span class="s2">"foo"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">s2</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">Literal</span><span class="p">(</span><span class="s2">"ba'r"</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">s3</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">Literal</span><span class="p">(</span><span class="mi">42</span><span class="p">)</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s1">', '</span><span class="p">)</span><span class="o">.</span><span class="n">join</span><span class="p">([</span><span class="n">s1</span><span class="p">,</span> <span class="n">s2</span><span class="p">,</span> <span class="n">s3</span><span class="p">])</span><span class="o">.</span><span class="n">as_string</span><span class="p">(</span><span class="n">conn</span><span class="p">))</span>
<span class="go">'foo', 'ba''r', 42</span>
</pre></div>
</div>
<dl class="attribute">
<dt id="psycopg2.sql.Literal.wrapped">
<code class="descname">wrapped</code><a class="headerlink" href="#psycopg2.sql.Literal.wrapped" title="Permalink to this definition">¶</a></dt>
<dd><p>The object wrapped by the <code class="xref py py-obj docutils literal"><span class="pre">Literal</span></code>.</p>
</dd></dl>
</dd></dl>
<dl class="class">
<dt id="psycopg2.sql.Placeholder">
<em class="property">class </em><code class="descclassname">psycopg2.sql.</code><code class="descname">Placeholder</code><span class="sig-paren">(</span><em>name=None</em><span class="sig-paren">)</span><a class="headerlink" href="#psycopg2.sql.Placeholder" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference internal" href="#psycopg2.sql.Composable" title="psycopg2.sql.Composable"><code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code></a> representing a placeholder for query parameters.</p>
<p>If the name is specified, generate a named placeholder (e.g. <code class="docutils literal"><span class="pre">%(name)s</span></code>),
otherwise generate a positional placeholder (e.g. <code class="docutils literal"><span class="pre">%s</span></code>).</p>
<p>The object is useful to generate SQL queries with a variable number of
arguments.</p>
<p>Examples:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">names</span> <span class="o">=</span> <span class="p">[</span><span class="s1">'foo'</span><span class="p">,</span> <span class="s1">'bar'</span><span class="p">,</span> <span class="s1">'baz'</span><span class="p">]</span>
<span class="gp">>>> </span><span class="n">q1</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s2">"insert into table ({}) values ({})"</span><span class="p">)</span><span class="o">.</span><span class="n">format</span><span class="p">(</span>
<span class="gp">... </span> <span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s1">', '</span><span class="p">)</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="nb">map</span><span class="p">(</span><span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">,</span> <span class="n">names</span><span class="p">)),</span>
<span class="gp">... </span> <span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s1">', '</span><span class="p">)</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">sql</span><span class="o">.</span><span class="n">Placeholder</span><span class="p">()</span> <span class="o">*</span> <span class="nb">len</span><span class="p">(</span><span class="n">names</span><span class="p">)))</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="n">q1</span><span class="o">.</span><span class="n">as_string</span><span class="p">(</span><span class="n">conn</span><span class="p">))</span>
<span class="go">insert into table ("foo", "bar", "baz") values (%s, %s, %s)</span>
<span class="gp">>>> </span><span class="n">q2</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s2">"insert into table ({}) values ({})"</span><span class="p">)</span><span class="o">.</span><span class="n">format</span><span class="p">(</span>
<span class="gp">... </span> <span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s1">', '</span><span class="p">)</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="nb">map</span><span class="p">(</span><span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">,</span> <span class="n">names</span><span class="p">)),</span>
<span class="gp">... </span> <span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s1">', '</span><span class="p">)</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="nb">map</span><span class="p">(</span><span class="n">sql</span><span class="o">.</span><span class="n">Placeholder</span><span class="p">,</span> <span class="n">names</span><span class="p">)))</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="n">q2</span><span class="o">.</span><span class="n">as_string</span><span class="p">(</span><span class="n">conn</span><span class="p">))</span>
<span class="go">insert into table ("foo", "bar", "baz") values (%(foo)s, %(bar)s, %(baz)s)</span>
</pre></div>
</div>
<dl class="attribute">
<dt id="psycopg2.sql.Placeholder.name">
<code class="descname">name</code><a class="headerlink" href="#psycopg2.sql.Placeholder.name" title="Permalink to this definition">¶</a></dt>
<dd><p>The name of the <code class="xref py py-obj docutils literal"><span class="pre">Placeholder</span></code>.</p>
</dd></dl>
</dd></dl>
<dl class="class">
<dt id="psycopg2.sql.Composed">
<em class="property">class </em><code class="descclassname">psycopg2.sql.</code><code class="descname">Composed</code><span class="sig-paren">(</span><em>seq</em><span class="sig-paren">)</span><a class="headerlink" href="#psycopg2.sql.Composed" title="Permalink to this definition">¶</a></dt>
<dd><p>A <a class="reference internal" href="#psycopg2.sql.Composable" title="psycopg2.sql.Composable"><code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code></a> object made of a sequence of <code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code>.</p>
<p>The object is usually created using <code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code> operators and methods.
However it is possible to create a <code class="xref py py-obj docutils literal"><span class="pre">Composed</span></code> directly specifying a
sequence of <code class="xref py py-obj docutils literal"><span class="pre">Composable</span></code> as arguments.</p>
<p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">comp</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">Composed</span><span class="p">(</span>
<span class="gp">... </span> <span class="p">[</span><span class="n">sql</span><span class="o">.</span><span class="n">SQL</span><span class="p">(</span><span class="s2">"insert into "</span><span class="p">),</span> <span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s2">"table"</span><span class="p">)])</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="n">comp</span><span class="o">.</span><span class="n">as_string</span><span class="p">(</span><span class="n">conn</span><span class="p">))</span>
<span class="go">insert into "table"</span>
</pre></div>
</div>
<p><code class="xref py py-obj docutils literal"><span class="pre">Composed</span></code> objects are iterable (so they can be used in <a class="reference internal" href="#psycopg2.sql.SQL.join" title="psycopg2.sql.SQL.join"><code class="xref py py-obj docutils literal"><span class="pre">SQL.join</span></code></a> for
instance).</p>
<dl class="attribute">
<dt id="psycopg2.sql.Composed.seq">
<code class="descname">seq</code><a class="headerlink" href="#psycopg2.sql.Composed.seq" title="Permalink to this definition">¶</a></dt>
<dd><p>The list of the content of the <code class="xref py py-obj docutils literal"><span class="pre">Composed</span></code>.</p>
</dd></dl>
<dl class="method">
<dt id="psycopg2.sql.Composed.join">
<code class="descname">join</code><span class="sig-paren">(</span><em>joiner</em><span class="sig-paren">)</span><a class="headerlink" href="#psycopg2.sql.Composed.join" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a new <code class="xref py py-obj docutils literal"><span class="pre">Composed</span></code> interposing the <em>joiner</em> with the <code class="xref py py-obj docutils literal"><span class="pre">Composed</span></code> items.</p>
<p>The <em>joiner</em> must be a <a class="reference internal" href="#psycopg2.sql.SQL" title="psycopg2.sql.SQL"><code class="xref py py-obj docutils literal"><span class="pre">SQL</span></code></a> or a string which will be interpreted as
an <a class="reference internal" href="#psycopg2.sql.SQL" title="psycopg2.sql.SQL"><code class="xref py py-obj docutils literal"><span class="pre">SQL</span></code></a>.</p>
<p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="gp">>>> </span><span class="n">fields</span> <span class="o">=</span> <span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s1">'foo'</span><span class="p">)</span> <span class="o">+</span> <span class="n">sql</span><span class="o">.</span><span class="n">Identifier</span><span class="p">(</span><span class="s1">'bar'</span><span class="p">)</span> <span class="c1"># a Composed</span>
<span class="gp">>>> </span><span class="k">print</span><span class="p">(</span><span class="n">fields</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="s1">', '</span><span class="p">)</span><span class="o">.</span><span class="n">as_string</span><span class="p">(</span><span class="n">conn</span><span class="p">))</span>
<span class="go">"foo", "bar"</span>
</pre></div>
</div>
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