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<h1 class="pudge-member-page-heading">SQLBuilder</h1>
<div class="contents topic" id="contents">
<p class="topic-title first">Contents</p>
<ul class="simple">
<li><a href="#sqlexpression" class="reference internal" id="id1">SQLExpression</a></li>
<li><a href="#sql-statements" class="reference internal" id="id2">SQL statements</a><ul>
<li><a href="#select" class="reference internal" id="id3">Select</a></li>
<li><a href="#insert" class="reference internal" id="id4">Insert</a></li>
<li><a href="#update" class="reference internal" id="id5">Update</a></li>
<li><a href="#delete" class="reference internal" id="id6">Delete</a></li>
<li><a href="#union" class="reference internal" id="id7">Union</a></li>
</ul>
</li>
<li><a href="#nested-sql-statements-subqueries" class="reference internal" id="id8">Nested SQL statements (subqueries)</a></li>
</ul>
</div>
<p>A number of variables from SQLBuilder are included with <tt class="docutils literal">from
sqlobject import *</tt> -- see the <a href="SQLObject.html#exported-symbols" class="reference external">relevant SQLObject documentation</a>
for more. Its functionality is also available through the special
<tt class="docutils literal">q</tt> attribute of <cite>SQLObject</cite> classes.</p>
<div class="section" id="sqlexpression">
<h1><a href="#id1" class="toc-backref">SQLExpression</a></h1>
<p>SQLExpression uses clever overriding of operators to make Python
expressions build SQL expressions -- so long as you start with a Magic
Object that knows how to fake it.</p>
<p>With SQLObject, you get a Magic Object by accessing the <tt class="docutils literal">q</tt> attribute
of a table class -- this gives you an object that represents the
field. All of this is probably easier to grasp in an example:</p>
<pre class="literal-block">
>>> from sqlobject.sqlbuilder import *
>>> person = table.person
# person is now equivalent to the Person.q object from the SQLObject
# documentation
>>> person
person
>>> person.first_name
person.first_name
>>> person.first_name == 'John'
person.first_name = 'John'
>>> name = 'John'
>>> person.first_name != name
person.first_name != 'John'
>>> AND(person.first_name == 'John', person.last_name == 'Doe')
(person.first_name = 'John' AND person.last_name = 'Doe')
</pre>
<p>Most of the operators work properly: <, >, <=, >=, !=, ==, +, -, /,
*, **, %. However, <tt class="docutils literal">and</tt>, <tt class="docutils literal">or</tt>, and <tt class="docutils literal">not</tt> <strong>do not work</strong>.
You can use &, |, and ~ instead -- but be aware that these have
the same precedence as multiplication. So:</p>
<pre class="literal-block">
# This isn't what you want:
>> person.first_name == 'John' & person.last_name == 'Doe'
(person.first_name = ('John' AND person.last_name)) = 'Doe')
# This is:
>> (person.first_name == 'John') & (person.last_name == 'Doe')
((person.first_name = 'John') AND (person.last_name == 'Doe'))
</pre>
<p>SQLBuilder also contains the functions <tt class="docutils literal">AND</tt>, <tt class="docutils literal">OR</tt>, and <tt class="docutils literal">NOT</tt> which
also work -- I find these easier to work with. <tt class="docutils literal">AND</tt> and <tt class="docutils literal">OR</tt> can
take any number of arguments.</p>
<p>You can also use <tt class="docutils literal">.startswith()</tt> and <tt class="docutils literal">.endswith()</tt> on an SQL
expression -- these will translate to appropriate <tt class="docutils literal">LIKE</tt> statements
and all <tt class="docutils literal">%</tt> quoting is handled for you, so you can ignore that
implementation detail. There is also a <tt class="docutils literal">LIKE</tt> function, where you
can pass your string, with <tt class="docutils literal">%</tt> for the wildcard, as usual.</p>
<p>If you want to access an SQL function, use the <tt class="docutils literal">func</tt> variable,
like:</p>
<pre class="literal-block">
>> person.created < func.NOW()
</pre>
<p>To pass a constant, use the <tt class="docutils literal">const</tt> variable which is actually an
alias for func.</p>
</div>
<div class="section" id="sql-statements">
<h1><a href="#id2" class="toc-backref">SQL statements</a></h1>
<p>SQLBuilder implements objects that execute SQL statements. SQLObject
uses them internally in its <a href="SQLObject.html" class="reference external">higher-level API</a>, but users can use this
mid-level API to execute SQL queries that are not supported by the
high-level API. To use these objects first construct an instance of a
statement object, then ask the connection to convert the instance to an
SQL query and finally ask the connection to execute the query and return
the results. For example, for <tt class="docutils literal">Select</tt> class:</p>
<pre class="literal-block">
>>> from sqlobject.sqlbuilder import *
>> select = Select(['name', 'AVG(salary)'], staticTables=['employees'],
>> groupBy='name') # create an instance
>> query = connection.sqlrepr(select) # Convert to SQL string:
>> # SELECT name, AVG(salary) FROM employees GROUP BY name
>> rows = connection.queryAll(query) # Execute the query
>> # and get back the results as a list of rows
>> # where every row is a sequence of length 2 (name and average salary)
</pre>
<div class="section" id="select">
<h2><a href="#id3" class="toc-backref">Select</a></h2>
<p>A class to build <tt class="docutils literal">SELECT</tt> queries. Accepts a number of parameters, all
parameters except <cite>items</cite> are optional. Use <tt class="docutils literal">connection.queryAll(query)</tt>
to execute the query and get back the results as a list of rows.</p>
<dl class="docutils">
<dt><cite>items</cite>:</dt>
<dd>A string, an SQLExpression or a sequence of strings or
SQLExpression's, represents the list of columns. If there are
q-values SQLExpression's <tt class="docutils literal">Select</tt> derives a list of tables for
SELECT query.</dd>
<dt><cite>where</cite>:</dt>
<dd>A string or an SQLExpression, represents the <tt class="docutils literal">WHERE</tt> clause.</dd>
<dt><cite>groupBy</cite>:</dt>
<dd>A string or an SQLExpression, represents the <tt class="docutils literal">GROUP BY</tt> clause.</dd>
<dt><cite>having</cite>:</dt>
<dd>A string or an SQLExpression, represents the <tt class="docutils literal">HAVING</tt> part of the
<tt class="docutils literal">GROUP BY</tt> clause.</dd>
<dt><cite>orderBy</cite>:</dt>
<dd>A string or an SQLExpression, represents the <tt class="docutils literal">ORDER BY</tt> clause.</dd>
<dt><cite>join</cite>:</dt>
<dd>A (list of) JOINs (<tt class="docutils literal">LEFT JOIN</tt>, etc.)</dd>
<dt><cite>distinct</cite>:</dt>
<dd>A bool flag to turn on <tt class="docutils literal">DISTINCT</tt> query.</dd>
<dt><cite>start</cite>, <cite>end</cite>:</dt>
<dd>Integers. The way to calculate <tt class="docutils literal">OFFSET</tt> and <tt class="docutils literal">LIMIT</tt>.</dd>
<dt><cite>limit</cite>:</dt>
<dd>An integer. <cite>limit</cite>, if passed, overrides <cite>end</cite>.</dd>
<dt><cite>reversed</cite>:</dt>
<dd>A bool flag to do <tt class="docutils literal">ORDER BY</tt> in the reverse direction.</dd>
<dt><cite>forUpdate</cite>:</dt>
<dd>A bool flag to turn on <tt class="docutils literal">SELECT FOR UPDATE</tt> query.</dd>
<dt><cite>staticTables</cite>:</dt>
<dd>A sequence of strings or SQLExpression's that name tables for
<tt class="docutils literal">FROM</tt>. This parameter must be used if <cite>items</cite> is a list of strings
from which Select cannot derive the list of tables.</dd>
</dl>
</div>
<div class="section" id="insert">
<h2><a href="#id4" class="toc-backref">Insert</a></h2>
<p>A class to build <tt class="docutils literal">INSERT</tt> queries. Accepts a number of parameters.
Use <tt class="docutils literal">connection.query(query)</tt> to execute the query.</p>
<dl class="docutils">
<dt><cite>table</cite>:</dt>
<dd>A string that names the table to <tt class="docutils literal">INSERT</tt> into. Required.</dd>
<dt><cite>valueList</cite>:</dt>
<dd><p class="first">A list of (key, value) sequences or {key: value} dictionaries; keys
are column names. Either <cite>valueList</cite> or <cite>values</cite> must be passed, but
not both. Example:</p>
<pre class="last literal-block">
>> insert = Insert('person', valueList=[('name', 'Test'), ('age', 42)])
# or
>> insert = Insert('person', valueList=[{'name': 'Test'}, {'age': 42}])
>> query = connection.sqlrepr(insert)
# Both generate the same query:
# INSERT INTO person (name, age) VALUES ('Test', 42)
>> connection.query(query)
</pre>
</dd>
<dt><cite>values</cite>:</dt>
<dd><p class="first">A dictionary {key: value}; keys are column names. Either <cite>valueList</cite>
or <cite>values</cite> must be passed, but not both. Example:</p>
<pre class="last literal-block">
>> insert = Insert('person', values={'name': 'Test', 'age': 42})
>> query = connection.sqlrepr(insert)
# The query is the same
# INSERT INTO person (name, age) VALUES ('Test', 42)
>> connection.query(query)
</pre>
</dd>
</dl>
<p>Instances of the class work fast and thus are suitable for
mass-insertion. If one needs to populate a database with SQLObject
running a lot of <tt class="docutils literal">INSERT</tt> queries this class is the way to go.</p>
</div>
<div class="section" id="update">
<h2><a href="#id5" class="toc-backref">Update</a></h2>
<p>A class to build <tt class="docutils literal">UPDATE</tt> queries. Accepts a number of parameters.
Use <tt class="docutils literal">connection.query(query)</tt> to execute the query.</p>
<dl class="docutils">
<dt><cite>table</cite>:</dt>
<dd>A string that names the table to <tt class="docutils literal">UPDATE</tt>. Required.</dd>
<dt><cite>values</cite>:</dt>
<dd>A dictionary {key: value}; keys are column names. Required.</dd>
<dt><cite>where</cite>:</dt>
<dd>An optional string or SQLExpression, represents the <tt class="docutils literal">WHERE</tt> clause.</dd>
</dl>
<p>Example:</p>
<pre class="literal-block">
>> update = Update('person',
>> values={'name': 'Test', 'age': 42}, where='id=1')
>> query = connection.sqlrepr(update)
# UPDATE person SET name='Test', age=42 WHERE id=1
>> connection.query(query)
</pre>
</div>
<div class="section" id="delete">
<h2><a href="#id6" class="toc-backref">Delete</a></h2>
<p>A class to build <tt class="docutils literal">DELETE FROM</tt> queries. Accepts a number of parameters.
Use <tt class="docutils literal">connection.query(query)</tt> to execute the query.</p>
<dl class="docutils">
<dt><cite>table</cite>:</dt>
<dd>A string that names the table to <tt class="docutils literal">UPDATE</tt>. Required.</dd>
<dt><cite>where</cite>:</dt>
<dd>An optional string or an SQLExpression, represents the <tt class="docutils literal">WHERE</tt>
clause. Required. If you need to delete all rows pass <tt class="docutils literal">where=None</tt>;
this is a safety measure.</dd>
</dl>
<p>Example:</p>
<pre class="literal-block">
>> update = Delete('person', where='id=1')
>> query = connection.sqlrepr(update)
# DELETE FROM person WHERE id=1
>> connection.query(query)
</pre>
</div>
<div class="section" id="union">
<h2><a href="#id7" class="toc-backref">Union</a></h2>
<p>A class to build <tt class="docutils literal">UNION</tt> queries. Accepts a number of parameters -
<tt class="docutils literal">Select</tt> queries. Use <tt class="docutils literal">connection.queryAll(query)</tt> to execute the
query and get back the results.</p>
<p>Example:</p>
<pre class="literal-block">
>> select1 = Select(['min', func.MIN(const.salary)], staticTables=['employees'])
>> select2 = Select(['max', func.MAX(const.salary)], staticTables=['employees'])
>> union = Union(select1, select2)
>> query = connection.sqlrepr(union)
# SELECT 'min', MIN(salary) FROM employees
# UNION
# SELECT 'max', MAX(salary) FROM employees
>> rows = connection.queryAll(query)
</pre>
</div>
</div>
<div class="section" id="nested-sql-statements-subqueries">
<h1><a href="#id8" class="toc-backref">Nested SQL statements (subqueries)</a></h1>
<p>There are a few special operators that receive as parameter SQL
statements. These are <tt class="docutils literal">IN</tt>, <tt class="docutils literal">NOTIN</tt>, <tt class="docutils literal">EXISTS</tt>, <tt class="docutils literal">NOTEXISTS</tt>,
<tt class="docutils literal">SOME</tt>, <tt class="docutils literal">ANY</tt> and <tt class="docutils literal">ALL</tt>. Consider the following example: You are
interested in removing records from a table using deleteMany. However,
the criterion for doing so depends on another table.</p>
<p>You would expect the following to work:</p>
<pre class="literal-block">
>> PersonWorkplace.deleteMany(where=
((PersonWorkplace.q.WorkplaceID==Workplace.q.id) &
(Workplace.q.id==SOME_ID)))
</pre>
<p>But this doesn't work! However, you can't do a join in a deleteMany
call. To work around this issue, use <tt class="docutils literal">IN</tt>:</p>
<pre class="literal-block">
>> PersonWorkplace.deleteMany(where=
IN(PersonWorkplace.q.WorkplaceID,
Select(Workplace.q.id, Workplace.q.id==SOME_ID)))
</pre>
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