Defines the base components of SQL expression trees.
All components are derived from a common base class ClauseElement. Common behaviors are organized based on class hierarchies, in some cases via mixins.
All object construction from this package occurs via functions which in some cases will construct composite ClauseElement structures together, and in other cases simply return a single ClauseElement constructed directly. The function interface affords a more "DSL-ish" feel to constructing SQL expressions and also allows future class reorganizations.
Even though classes are not constructed directly from the outside, most classes which have additional public methods are considered to be public (i.e. have no leading underscore). Other classes which are "semi-public" are marked with a single leading underscore; these classes usually have few or no public methods and are less guaranteed to stay the same in future releases.
Return an Alias object.
An Alias represents any FromClause with an alternate name assigned within SQL, typically using the AS clause when generated, e.g. SELECT * FROM table AS aliasname.
Similar functionality is available via the alias() method available on all FromClause subclasses.
- selectable
- any FromClause subclass, such as a table, select statement, etc..
- alias
- string name to be assigned as the alias. If None, a random name will be generated.
Join a list of clauses together using the AND operator.
The & operator is also overloaded on all _CompareMixin subclasses to produce the same result.
Return a BETWEEN predicate clause.
Equivalent of SQL clausetest BETWEEN clauseleft AND clauseright.
The between() method on all _CompareMixin subclasses provides similar functionality.
Create a bind parameter clause with the given key.
Produce a CASE statement.
The expressions used for THEN and ELSE, when specified as strings, will be interpreted as bound values. To specify textual SQL expressions for these, use the text(<string>) construct.
The expressions used for the WHEN criterion may only be literal strings when "value" is present, i.e. CASE table.somecol WHEN "x" THEN "y". Otherwise, literal strings are not accepted in this position, and either the text(<string>) or literal(<string>) constructs must be used to interpret raw string values.
Usage examples:
case([(orderline.c.qty > 100, item.c.specialprice), (orderline.c.qty > 10, item.c.bulkprice) ], else_=item.c.regularprice) case(value=emp.c.type, whens={ 'engineer': emp.c.salary * 1.1, 'manager': emp.c.salary * 3, })
Return a CAST function.
Equivalent of SQL CAST(clause AS totype).
Use with a TypeEngine subclass, i.e:
cast(table.c.unit_price * table.c.qty, Numeric(10,4))
or:
cast(table.c.timestamp, DATE)
Return a textual column clause, as would be in the columns clause of a SELECT statement.
The object returned is an instance of _ColumnClause, which represents the "syntactical" portion of the schema-level Column object.
Return an EXCEPT of multiple selectables.
The returned object is an instance of CompoundSelect.
Return an EXCEPT ALL of multiple selectables.
The returned object is an instance of CompoundSelect.
Return an EXISTS clause as applied to a Select object.
Calling styles are of the following forms:
# use on an existing select() s = select([<columns>]).where(<criterion>) s = exists(s) # construct a select() at once exists(['*'], **select_arguments).where(<criterion>) # columns argument is optional, generates "EXISTS (SELECT *)" # by default. exists().where(<criterion>)
Return an Insert clause element.
Similar functionality is available via the insert() method on Table.
If both values and compile-time bind parameters are present, the compile-time bind parameters override the information specified within values on a per-key basis.
The keys within values can be either Column objects or their string identifiers. Each key may reference one of:
If a SELECT statement is specified which references this INSERT statement's table, the statement will be correlated against the INSERT statement.
Return an INTERSECT of multiple selectables.
The returned object is an instance of CompoundSelect.
Return an INTERSECT ALL of multiple selectables.
The returned object is an instance of CompoundSelect.
Return a JOIN clause element (regular inner join).
The returned object is an instance of Join.
Similar functionality is also available via the join() method on any FromClause.
To chain joins together, use the join() or outerjoin() methods on the resulting Join object.
Return a _Label object for the given ColumnElement.
A label changes the name of an element in the columns clause of a SELECT statement, typically via the AS SQL keyword.
This functionality is more conveniently available via the label() method on ColumnElement.
Return a literal clause, bound to a bind parameter.
Literal clauses are created automatically when non- ClauseElement objects (such as strings, ints, dates, etc.) are used in a comparison operation with a _CompareMixin subclass, such as a Column object. Use this function to force the generation of a literal clause, which will be created as a _BindParamClause with a bound value.
Return a textual column expression, as would be in the columns clause of a SELECT statement.
The object returned supports further expressions in the same way as any other column object, including comparison, math and string operations. The type_ parameter is important to determine proper expression behavior (such as, '+' means string concatenation or numerical addition based on the type).
Return a negation of the given clause, i.e. NOT(clause).
The ~ operator is also overloaded on all _CompareMixin subclasses to produce the same result.
Join a list of clauses together using the OR operator.
The | operator is also overloaded on all _CompareMixin subclasses to produce the same result.
Return an OUTER JOIN clause element.
The returned object is an instance of Join.
Similar functionality is also available via the outerjoin() method on any FromClause.
To chain joins together, use the join() or outerjoin() methods on the resulting Join object.
Create an 'OUT' parameter for usage in functions (stored procedures), for databases which support them.
The outparam can be used like a regular function parameter. The "output" value will be available from the ResultProxy object via its out_parameters attribute, which returns a dictionary containing the values.
Returns a SELECT clause element.
Similar functionality is also available via the select() method on any FromClause.
The returned object is an instance of Select.
All arguments which accept ClauseElement arguments also accept string arguments, which will be converted as appropriate into either text() or literal_column() constructs.
A list of ClauseElement objects, typically ColumnElement objects or subclasses, which will form the columns clause of the resulting statement. For all members which are instances of Selectable, the individual ColumnElement members of the Selectable will be added individually to the columns clause. For example, specifying a Table instance will result in all the contained Column objects within to be added to the columns clause.
This argument is not present on the form of select() available on Table.
Additional parameters include:
Return a Table object.
This is a primitive version of the Table object, which is a subclass of this object.
Create literal text to be inserted into a query.
When constructing a query from a select(), update(), insert() or delete(), using plain strings for argument values will usually result in text objects being created automatically. Use this function when creating textual clauses outside of other ClauseElement objects, or optionally wherever plain text is to be used.
Return a UNION of multiple selectables.
The returned object is an instance of CompoundSelect.
A similar union() method is available on all FromClause subclasses.
Return a UNION ALL of multiple selectables.
The returned object is an instance of CompoundSelect.
A similar union_all() method is available on all FromClause subclasses.
Return an Update clause element.
Similar functionality is available via the update() method on Table.
If both values and compile-time bind parameters are present, the compile-time bind parameters override the information specified within values on a per-key basis.
The keys within values can be either Column objects or their string identifiers. Each key may reference one of:
If a SELECT statement is specified which references this UPDATE statement's table, the statement will be correlated against the UPDATE statement.
Represents an table or selectable alias (AS).
Represents an alias, as typically applied to any table or sub-select within a SQL statement using the AS keyword (or without the keyword on certain databases such as Oracle).
This object is constructed from the alias() module level function as well as the alias() method available on all FromClause subclasses.
Base class for elements of a programmatically constructed SQL expression.
Returns the Engine or Connection to which this ClauseElement is bound, or None if none found.
Compare this ClauseElement to the given ClauseElement.
Subclasses should override the default behavior, which is a straight identity comparison.
Compile this SQL expression.
The return value is a Compiled object. Calling str() or unicode() on the returned value will yield a string representation of the result. The Compiled object also can return a dictionary of bind parameter names and values using the params accessor.
Return immediate child elements of this ClauseElement.
This is used for visit traversal.
**kwargs may contain flags that change the collection that is returned, for example to return a subset of items in order to cut down on larger traversals, or to return child items from a different context (such as schema-level collections instead of clause-level).
Return a copy with bindparam() elments replaced.
Returns a copy of this ClauseElement with bindparam() elements replaced with values taken from the given dictionary:
>>> clause = column('x') + bindparam('foo') >>> print clause.compile().params {'foo':None} >>> print clause.params({'foo':7}).compile().params {'foo':7}
Compile and execute this ClauseElement, returning the result's scalar representation.
Return a copy with bindparam() elments replaced.
Same functionality as params(), except adds unique=True to affected bind parameters so that multiple statements can be used.
An ordered dictionary that stores a list of ColumnElement instances.
Overrides the __eq__() method to produce SQL clauses between sets of correlated columns.
Add a column to this collection.
The key attribute of the column will be used as the hash key for this dictionary.
add the given column to this collection, removing unaliased versions of this column as well as existing columns with the same key.
e.g.:
t = Table('sometable', Column('col1', Integer)) t.replace_unalised(Column('col1', Integer, key='columnone'))will remove the original 'col1' from the collection, and add the new column under the name 'columnname'.
Used by schema.Column to override columns during table reflection.
Represent an element that is usable within the "column clause" portion of a SELECT statement.
This includes columns associated with tables, aliases, and subqueries, expressions, function calls, SQL keywords such as NULL, literals, etc. ColumnElement is the ultimate base class for all such elements.
ColumnElement supports the ability to be a proxy element, which indicates that the ColumnElement may be associated with a Selectable which was derived from another Selectable. An example of a "derived" Selectable is an Alias of a Table.
A ColumnElement, by subclassing the _CompareMixin mixin class, provides the ability to generate new ClauseElement objects using Python expressions. See the _CompareMixin docstring for more details.
Return True if the given ColumnElement has a common ancestor to this ColumnElement.
Represent an element that can be used within the FROM clause of a SELECT statement.
attrgetter(attr, ...) --> attrgetter object
Return a callable object that fetches the given attribute(s) from its operand. After, f=attrgetter('name'), the call f(r) returns r.name. After, g=attrgetter('name', 'date'), the call g(r) returns (r.name, r.date).
attrgetter(attr, ...) --> attrgetter object
Return a callable object that fetches the given attribute(s) from its operand. After, f=attrgetter('name'), the call f(r) returns r.name. After, g=attrgetter('name', 'date'), the call g(r) returns (r.name, r.date).
Given a ColumnElement, return the exported ColumnElement object from this Selectable which corresponds to that original Column via a common anscestor column.
return a SELECT COUNT generated against this FromClause.
a brief description of this FromClause.
Used primarily for error message formatting.
Return True if this FromClause is 'derived' from the given FromClause.
An example would be an Alias of a Table is derived from that Table.
return a join of this FromClause against another FromClause.
return an outer join of this FromClause against another FromClause.
attrgetter(attr, ...) --> attrgetter object
Return a callable object that fetches the given attribute(s) from its operand. After, f=attrgetter('name'), the call f(r) returns r.name. After, g=attrgetter('name', 'date'), the call g(r) returns (r.name, r.date).
attrgetter(attr, ...) --> attrgetter object
Return a callable object that fetches the given attribute(s) from its operand. After, f=attrgetter('name'), the call f(r) returns r.name. After, g=attrgetter('name', 'date'), the call g(r) returns (r.name, r.date).
replace all occurences of FromClause 'old' with the given Alias object, returning a copy of this FromClause.
Construct a new Insert.
Add a word or expression between INSERT and INTO. Generative.
If multiple prefixes are supplied, they will be separated with spaces.
represent a JOIN construct between two FromClause elements.
The public constructor function for Join is the module-level join() function, as well as the join() method available off all FromClause subclasses.
Create a Select out of this Join clause and return an Alias of it.
The Select is not correlating.
Create a Select from this Join.
Represents a SELECT statement.
Select statements support appendable clauses, as well as the ability to execute themselves and return a result set.
Construct a Select object.
The public constructor for Select is the select() function; see that function for argument descriptions.
Additional generative and mutator methods are available on the _SelectBaseMixin superclass.
append the given column expression to the columns clause of this select() construct.
append the given correlation expression to this select() construct.
append the given FromClause expression to this select() construct's FROM clause.
append the given expression to this select() construct's HAVING criterion.
The expression will be joined to existing HAVING criterion via AND.
append the given columns clause prefix expression to this select() construct.
append the given expression to this select() construct's WHERE criterion.
The expression will be joined to existing WHERE criterion via AND.
return a new select() construct with the given column expression added to its columns clause.
return a new select() construct which will correlate the given FROM clauses to that of an enclosing select(), if a match is found.
By "match", the given fromclause must be present in this select's list of FROM objects and also present in an enclosing select's list of FROM objects.
Calling this method turns off the select's default behavior of "auto-correlation". Normally, select() auto-correlates all of its FROM clauses to those of an embedded select when compiled.
If the fromclause is None, correlation is disabled for the returned select().
return a SQL EXCEPT of this select() construct against the given selectable.
return a SQL EXCEPT ALL of this select() construct against the given selectable.
return child elements as per the ClauseElement specification.
return a new select() construct with the given expression added to its HAVING clause, joined to the existing clause via AND, if any.
an iterator of all ColumnElement expressions which would be rendered into the columns clause of the resulting SELECT statement.
return a SQL INTERSECT of this select() construct against the given selectable.
return a SQL INTERSECT ALL of this select() construct against the given selectable.
return a new select() construct which will apply the given expression to the start of its columns clause, not using any commas.
return a new select() construct with the given FROM expression applied to its list of FROM objects.
return a 'grouping' construct as per the ClauseElement specification.
This produces an element that can be embedded in an expression. Note that this method is called automatically as needed when constructing expressions.
return a SQL UNION of this select() construct against the given selectable.
return a SQL UNION ALL of this select() construct against the given selectable.
return a new select() construct with the given expression added to its WHERE clause, joined to the existing clause via AND, if any.
return a new select() construct with its columns clause replaced with the given columns.
Represents a "table" construct.
Note that this represents tables only as another syntactical construct within SQL expressions; it does not provide schema-level functionality.
Construct a new Update.
return a new update() construct with the given expression added to its WHERE clause, joined to the existing clause via AND, if any.
Defines comparison and math operations for ClauseElement instances.
Produce a BETWEEN clause, i.e. <column> BETWEEN <cleft> AND <cright>
Produce a column label, i.e. <columnname> AS <name>.
if 'name' is None, an anonymous label name will be generated.
Produce a MATCH clause, i.e. MATCH '<other>'
The allowed contents of other are database backend specific.
produce a generic operator function.
e.g.:
somecolumn.op("*")(5)
produces:
somecolumn * 5
Base class for Select and CompoundSelects.
Construct a new _SelectBaseMixin.
Append the given GROUP BY criterion applied to this selectable.
The criterion will be appended to any pre-existing GROUP BY criterion.
Append the given ORDER BY criterion applied to this selectable.
The criterion will be appended to any pre-existing ORDER BY criterion.
return a new selectable with the 'use_labels' flag set to True.
This will result in column expressions being generated using labels against their table name, such as "SELECT somecolumn AS tablename_somecolumn". This allows selectables which contain multiple FROM clauses to produce a unique set of column names regardless of name conflicts among the individual FROM clauses.
return a 'scalar' representation of this selectable, which can be used as a column expression.
Typically, a select statement which has only one column in its columns clause is eligible to be used as a scalar expression.
The returned object is an instance of _ScalarSelect.
return a new selectable with the given list of GROUP BY criterion applied.
The criterion will be appended to any pre-existing GROUP BY criterion.
return a 'scalar' representation of this selectable, embedded as a subquery with a label.
See also as_scalar().
return a new selectable with the given list of ORDER BY criterion applied.
The criterion will be appended to any pre-existing ORDER BY criterion.
mark a ClauseElement as 'immutable' when expressions are cloned.
specify the VALUES clause for an INSERT statement, or the SET clause for an UPDATE.
Form the base for INSERT, UPDATE, and DELETE statements.