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construct sql query in python rather than performing tons of string manipulation. Take a look at docstring of StandardSelect and OracleSelect for a hint on how the module should be used.

Python, 976 lines
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try:
    frozenset
except NameError:
    from sets import ImmutableSet as frozenset

def indent(width, s):
    space = width * ' '
    return '\n'.join([(space + line) for line in s.split('\n')])

def make_indenter(width):
    def indenter(s): return indent(width, s)
    return indenter

class AutoIndent(object):
    r"""AutoIndent

    replace bracketed template '( %s )' with multi-line template that will
    block-indents elements when interpolated with parameter

        >>> s1 = AutoIndent('speak(%s)')
        >>> s2 = AutoIndent('speak( %s )')

        >>> word = 'hello'
        >>> paragraph = '\n'.join(['Hello !', 'How are you ?', 'It\'s nice to see you.'])
    
        >>> print s1 % word
        speak(hello)

        >>> print s2 % paragraph
        speak(
          Hello !
          How are you ?
          It's nice to see you.
        )
    """
    def __init__(self, template):
        super(AutoIndent, self).__init__()
        multiline = template.count('( %s )')
        if multiline and (multiline != template.count('%s')):
            raise ValueError('Template must be homogenious')
        self.template = template.replace('( %s )', '(\n%s\n)')
        if multiline:
            self.indent = make_indenter(2)
        else:
            self.indent = lambda x: x
    def __mod__(self, value):
        if isinstance(value, basestring):
            t = (self.indent(value),)
        else:
            t = tuple([self.indent(v) for v in value])
        return self.template % t

def multiline(s):
    r"""multiline

        >>> multiline('Hello there')
        False

        >>> multiline('\n'.join(['Hello', 'there']))
        True
    """
    return s.find('\n') >= 0

class Source(object):
    """Source

        >>> i = Source('items')
        >>> print i.ITEM_ID
        items.ITEM_ID
    """
    def __init__(self, alias):
        super(Source, self).__init__()
        self.alias = alias
        self.fields = {}
    def __getattr__(self, name):
        if name in self.fields:
            return self.fields[name]
        else:
            f = Field(self, name)
            self.fields[name] = f
            return f
    def __str__(self): return self.alias
    def declaration(self): raise NotImplementedError()

class StatementSource(Source):
    """StatementSource

        >>> s = StatementSource('items', 'select * from IMA')
        >>> print s.declaration()
        (
          select * from IMA
        ) items
    """
    def __init__(self, alias, statement):
        super(StatementSource, self).__init__(alias)
        self.statement = statement
    def declaration(self):
        return AutoIndent('( %s ) ') % str(self.statement) + self.alias

class NamedSource(Source):
    """NamedSource

        >>> i = NamedSource('items', 'i')
        >>> print i
        i
        >>> print i.ITEM_ID
        i.ITEM_ID
    """
    def __init__(self, name, alias=None):
        super(NamedSource, self).__init__(alias)
        self.name = name
    def __str__(self): return self.alias or self.name
    def declaration(self):
        if self.alias:
            return '%s %s' % (self.name, self.alias)
        else:
            return self.name

class Expression(object): pass

class CustomExpression(Expression):
    def __init__(self, text): self.text = text
    def __str__(self): return str(self.text)

custom = CustomExpression

class StringLiteralExpression(Expression):
    """StringLiteralExpression

        >>> s = StringLiteralExpression('Huh?')
        >>> print s
        'Huh?'
    """
    def __init__(self, text): self.text = text
    def __str__(self): return "'%s'" % (self.text.replace("'", "''"))
    def expression(cls, expr):
        if isinstance(expr, Expression) and not isinstance(expr, cls): return expr
        else: return cls(expr)
    expression = classmethod(expression)

strlit = StringLiteralExpression.expression

class BooleanExpression(Expression): pass

class UnaryOperated(object):
    def __init__(self, element):
        super(UnaryOperated, self).__init__()
        self.element = element
    def __nonzero__(self): return bool(self.element)

class BinaryOperated(object):
    def __init__(self, *elements):
        super(BinaryOperated, self).__init__()
        self.elements = elements
    def __len__(self): return len(self.elements)
    def __nonzero__(self):
        for e in self.elements:
            if e: return True
        return False

class IsNull(UnaryOperated, Expression):
    """IsNull

        >>> print IsNull('ITEM_ID')
        ITEM_ID is null
    """
    def __str__(self): return '%s is null' % str(self.element)

class Blanket(UnaryOperated, Expression):
    def __str__(self):
        s = str(self.element)
        if multiline(s): return AutoIndent('( %s )') % s
        else: return '(%s)' % s

def blanket(expression):
    """blanket

        >>> print blanket('Huh?')
        (Huh?)

        >>> print blanket(blanket('Huh?'))
        (Huh?)
    """
    if isinstance(expression, Blanket):
        return expression
    else:
        return Blanket(expression)

def is_composite(expr):
    """is_composite

        >>> is_composite(Not('1=1'))
        False
    
        >>> is_composite(And('1=1'))
        False

        >>> is_composite(And('1=1', '2=2'))
        True
    """
    return isinstance(expr, BinaryOperated) and (len(expr) > 1)

def blanket_as_needed(expression):
    """blanket_as_needed

        >>> print blanket_as_needed('Huh?')
        (Huh?)

        >>> print blanket_as_needed(Not('0=0'))
        not (0=0)

        >>> print blanket_as_needed(And('0=0', '1=1', '2=2'))
        (
          (0=0) and
          (1=1) and
          (2=2)
        )
    """
    if is_composite(expression) or isinstance(expression, basestring): return Blanket(expression)
    else: return expression


class Prefixed(UnaryOperated):
    def __init__(self, prefix, element):
        super(Prefixed, self).__init__(element)
        self.prefix = prefix
    def __str__(self): return '%s %s' % (self.prefix, str(blanket_as_needed(self.element)))

class Infixed(BinaryOperated):
    def __init__(self, infix, *elements):
        super(Infixed, self).__init__(*elements)
        self.infix = infix
    def __str__(self): return (' %s ' % self.infix).join([str(blanket_as_needed(e)) for e in self.elements if e])

class PrefixedExpression(Prefixed, Expression):
    def __init__(self, prefix, expression):
        Prefixed.__init__(self, prefix, expression)
        Expression.__init__(self)

class Plus(PrefixedExpression):
    def __init__(self, expression): super(Plus, self).__init__('+', expression)

class Minus(PrefixedExpression):
    def __init__(self, expression): super(Minus, self).__init__('-', expression)

class PrefixedBooleanExpression(Prefixed, BooleanExpression):
    def __init__(self, prefix, boolexpr):
        Prefixed.__init__(self, prefix, boolexpr)
        Expression.__init__(self)

class Not(Prefixed, BooleanExpression):
    """Not

        >>> print Not('0=0')
        not (0=0)
    """
    def __init__(self, boolexpr): super(Not, self).__init__('not', boolexpr)

def invert(boolexpr):
    """invert

        >>> print invert('0=0')
        not (0=0)
    
        >>> print invert(invert('0=0'))
        0=0
    """
    if isinstance(boolexpr, Not):
        return boolexpr.element
    else:
        return Not(boolexpr)

class Combinative(object):
    
    def combine(cls, *combinatives):
        args = []
        for c in combinatives:
            if type(c) is cls:
                args.extend([e for e in c.elements if e])
            else:
                args.append(c)
        return cls(*args)
    combine = classmethod(combine)

class InfixedExpression(Infixed, Expression):
    def __init__(self, infix, *expressions):
        Infixed.__init__(self, infix, *expressions)
        Expression.__init__(self)

class Add(InfixedExpression, Combinative):
    """Add

        >>> print Add(1,2,3)
        1 + 2 + 3

        >>> print Add.combine(1,2,3)
        1 + 2 + 3

        >>> print Add.combine(1, Add(2,3), 4)
        1 + 2 + 3 + 4
    """
    def __init__(self, *expressions): super(Add, self).__init__('+', *expressions)

class Sub(InfixedExpression):
    def __init__(self, *expressions): super(Sub, self).__init__('-', *expressions)

class Mul(InfixedExpression, Combinative):
    def __init__(self, *expressions): super(Mul, self).__init__('*', *expressions)

class Div(InfixedExpression):
    def __init__(self, *expressions): super(Div, self).__init__('/', *expressions)

class InfixedBooleanExpression(Infixed, BooleanExpression):
    def __init__(self, infix, *boolexprs):
        Infixed.__init__(self, infix, *boolexprs)
        BooleanExpression.__init__(self)
    def __str__(self): return (' %s\n' % self.infix).join([str(blanket(e)) for e in self.elements])

class And(InfixedBooleanExpression, Combinative):
    """And

        >>> print And('0=0', '1=1', '2=2')
        (0=0) and
        (1=1) and
        (2=2)
    """
    def __init__(self, *boolexprs): super(And, self).__init__('and', *boolexprs)

class Or(InfixedBooleanExpression, Combinative):
    def __init__(self, *boolexprs): super(Or, self).__init__('or', *boolexprs)

class InfixedComparisonExpression(Infixed, BooleanExpression):
    def __init__(self, infix, left, right):
        if isinstance(left, basestring): left = strlit(left)
        if isinstance(right, basestring): right = strlit(right)
        Infixed.__init__(self, infix, left, right)
        BooleanExpression.__init__(self)
    left = property(lambda self: self.elements[0])
    right = property(lambda self: self.elements[1])

class Like(InfixedComparisonExpression):
    """Like

        >>> print Like(custom('ITEM_NAME'), 'Staron%')
        ITEM_NAME like 'Staron%'
    """
    def __init__(self, value, pattern):
        super(Like, self).__init__('like', value, pattern)

class LessThan(InfixedComparisonExpression):
    """LessThan
    
        >>> lessthan = LessThan(1, 2)
        >>> print lessthan
        1 < 2
        >>> lessthan.left
        1
        >>> lessthan.right
        2
    """
    def __init__(self, left, right): super(LessThan, self).__init__('<', left, right)

class LessThanOrEqual(InfixedComparisonExpression):
    def __init__(self, left, right): super(LessThanOrEqual, self).__init__('<=', left, right)

class GreaterThan(InfixedComparisonExpression):
    def __init__(self, left, right): super(GreaterThan, self).__init__('>', left, right)

class GreaterThanOrEqual(InfixedComparisonExpression):
    def __init__(self, left, right): super(GreaterThanOrEqual, self).__init__('>=', left, right)

class Equal(InfixedComparisonExpression):
    def __init__(self, left, right): super(Equal, self).__init__('=', left, right)

class OracleOuterDecorator(InfixedComparisonExpression):
    def __init__(self, decorated, left_outer=True):
        super(OracleOuterDecorator, self).__init__(decorated.infix, decorated.left, decorated.right)
        self.decorated = decorated
        self.left_outer = left_outer
    def __str__(self):
        if self.left_outer:
            return '%s %s %s(+)' % (self.left, self.infix, self.right)
        else:
            return '%s(+) %s %s' % (self.left, self.infix, self.right)

class NotEqual(InfixedComparisonExpression):
    def __init__(self, left, right): super(NotEqual, self).__init__('<>', left, right)

class Field(Expression):
    r"""Field

        >>> name = Field('item', 'ITEM_NAME')
        >>> price = Field('item', 'PRICE')
        >>> cost = Field('item', 'COST')
        >>> quantity = Field('invoice', 'QUANTITY')
    
        >>> print '\n'.join([str(x) for x in [name, price, cost, quantity]])
        item.ITEM_NAME
        item.PRICE
        item.COST
        invoice.QUANTITY

        >>> print price > cost
        item.PRICE > item.COST

        >>> print price * quantity
        item.PRICE * invoice.QUANTITY

        >>> print name.like('Staron%')
        item.ITEM_NAME like 'Staron%'

        >>> print name.is_null
        item.ITEM_NAME is null
    """
    
    def __init__(self, source, fieldname):
        super(Field, self).__init__()
        self.source = source
        self.fieldname = fieldname
    def __str__(self): return '%s.%s' % (str(self.source), self.fieldname)
    def __add__(self, other): return Add(self, other)
    def __radd__(self, other): return Add(other, self)
    def __sub__(self, other): return Sub(self, other)
    def __rsub__(self, other): return Sub(other, self)
    def __mul__(self, other): return Mul(self, other)
    def __rmul__(self, other): return Mul(other, self)
    def __div__(self, other): return Div(self, other)
    def __rdiv__(self, other): return Div(other, self)
    def __pos__(self): return Plus(self)
    def __neg__(self): return Minus(self)
    def __pow__(self, other): raise NotImplementedError()
    def __rpow__(self, other): raise NotImplementedError()
    def __abs__(self): raise NotImplementedError()
    def __mod__(self, other): raise NotImplementedError()
    def __rmod__(self, other): raise NotImplementedError()
    def __lt__(self, other): return LessThan(self, other)
    def __le__(self, other): return LessThanOrEqual(self, other)
    def __gt__(self, other): return GreaterThan(self, other)
    def __ge__(self, other): return GreaterThanOrEqual(self, other)
    def __eq__(self, other): return Equal(self, other)
    def __ne__(self, other): return NotEqual(self, other)
    def __and__(self, other): return And(self, other)
    def __rand__(self, other): return And(other, self)
    def __or__(self, other): return Or(self, other)
    def __ror__(self, other): return Or(other, self)
    is_null = property(lambda self: IsNull(self))
    def like(self, other): return Like(self, other)

class SourceList(object):
    """SourceList

        >>> s = SourceList()
        >>> item = s('ITEMS')
        >>> print item
        ITEMS
    
        >>> s('ITEMS')
        Traceback (most recent call last):
          ...
        ValueError: Duplicated key ('ITEMS')
    """
    def __init__(self):
        super(SourceList, self).__init__()
        self.clear()
        
    def clear(self):
        self.keys = []
        self.exprs = []
        self.aliases = []
        
    def clone(self):
        r = SourceList()
        r.assign(self)
        return r
    
    def assign(self, other):
        self.keys = list(other.keys)
        self.exprs = list(other.exprs)
        self.aliases = list(other.aliases)
        
    def __str__(self):
        def line(expr, alias):
            if not alias: return str(expr)
            return '%s %s' % (str(expr), str(alias))
        return ',\n'.join([line(expr, alias) for expr, alias in zip(self.exprs, self.aliases)])

    def __iter__(self): return iter(self.exprs)
        
    def _append(self, expr, alias):
        if isinstance(expr, Source):
            key = str(expr)
        else:
            key = str(alias or expr)
        if key in self.keys: raise ValueError("Duplicated key ('%s')" % key)
        self.keys.append(key)
        self.exprs.append(expr)
        self.aliases.append(alias)
    def __call__(self, name, alias=None):
        result = NamedSource(name, alias)
        self._append(result, alias)
        return result
    def statement(self, alias, statement):
        result = StatementSource(alias, statement)
        self._append(result, alias)
        return result

def iter_fields(expression):
    r"""iter_fields

        >>> ima = NamedSource('ima')
        >>> wko = NamedSource('wko')
        >>> join = And(ima.IMA_ItemID == wko.WKO_ItemID,
        ...            ima.IMA_UnitMeasure == wko.WKO_UnitMeasure,
        ...            Or(ima.IMA_ItemPrice.is_null, wko.WKO_WorkOrderDate == 3))
        ...
        >>> print '\n'.join([str(x) for x in iter_fields(join)])
        ima.IMA_ItemID
        wko.WKO_ItemID
        ima.IMA_UnitMeasure
        wko.WKO_UnitMeasure
        ima.IMA_ItemPrice
        wko.WKO_WorkOrderDate
    """
    if isinstance(expression, Field):
        yield expression
    elif isinstance(expression, UnaryOperated) and isinstance(expression, Expression):
        for x in iter_fields(expression.element):
            yield x
    elif isinstance(expression, BinaryOperated) and isinstance(expression, Expression):
        for expr in expression.elements:
            for x in iter_fields(expr):
                yield x

class FieldList(object):
    """FieldList

        >>> fields = FieldList()

        >>> print fields
        <BLANKLINE>
    
        >>> sources = SourceList()
        >>> ima = sources('IMA')
        >>> wko = sources('WKO')
    
        >>> fields.append(ima.IMA_ItemID)
        >>> len(fields)
        1
        >>> fields.append(wko.IMA_ItemID)
        Traceback (most recent call last):
          ...
        ValueError: Duplicated key ('IMA_ItemID')

        >>> fields.append(wko.IMA_ItemID, 'ITEM_ID')
        >>> len(fields)
        2

        >>> fields.append(ima.WKO_ItemID, 'ITEM_ID')
        Traceback (most recent call last):
          ...
        ValueError: Duplicated key ('ITEM_ID')

        >>> len(fields)
        2

        >>> fields.append('getdate()', 'TODAY')
        >>> len(fields)
        3
        >>> print fields
        IMA.IMA_ItemID                                     IMA_ItemID,
        WKO.IMA_ItemID                                     ITEM_ID,
        getdate()                                          TODAY

        >>> fields = FieldList()
        >>> fields.append(ima.IMA_ItemID)
        >>> fields.append(wko.WKO_ItemID)
        >>> fields.append('DATE')
        >>> print fields
        IMA.IMA_ItemID,
        WKO.WKO_ItemID,
        DATE
    """
    def __init__(self):
        super(FieldList, self).__init__()
        self.clear()
    def clear(self):
        self.keys = []
        self.values = []
        self.aliases = []
    def clone(self):
        r = FieldList()
        r.assign(self)
        return r
    def assign(self, other):
        self.keys = list(other.keys)
        self.values = list(other.values)
        self.aliases = list(other.aliases)
    def __len__(self): return len(self.keys)
    def __str__(self):
        if self.some_was_aliased():
            def line(key, value, alias): return '%-50s %s' % (str(value), str(key or alias or value))
            return ',\n'.join([line(k,v,a) for k,v,a in zip(self.keys, self.values, self.aliases)])
        else:
            return ',\n'.join([str(v) for v in self.values])
    def _check_key(self, key):
        if (key is not None) and (key in self.keys):
            raise ValueError("Duplicated key ('%s')" % key)
    def _do_append(self, key, value, alias):
        self._check_key(key)
        self.keys.append(key)
        self.values.append(value)
        self.aliases.append(alias)
    def _append_value(self, value, alias): self._do_append(alias, value, alias)
    def _append_field(self, field, alias): self._do_append(alias or field.fieldname, field, alias)
    def some_was_aliased(self):
        return [a for a in self.aliases if a is not None]
    def append(self, value, alias=None):
        if isinstance(value, Field):
            self._append_field(value, alias)
        else:
            self._append_value(value, alias)

class BooleanExpressionList(object):
    """BooleanExpressionList

        >>> exprs = BooleanExpressionList()
        >>> print exprs
        <BLANKLINE>

        >>> exprs.And('1=1')
        >>> print exprs
        (1=1)

        >>> exprs.invert()
        >>> print exprs
        not (1=1)

        >>> exprs.invert()
        >>> print exprs
        (1=1)

        >>> exprs.And('2=2')
        >>> print exprs
        (1=1) and
        (2=2)

        >>> exprs.Or('3=3', '4=4', '5=5')
        >>> print exprs
        (
          (1=1) and
          (2=2)
        ) or
        (3=3) or
        (4=4) or
        (5=5)

        >>> exprs.Or('6=6', '7=7')
        >>> print exprs
        (
          (1=1) and
          (2=2)
        ) or
        (3=3) or
        (4=4) or
        (5=5) or
        (6=6) or
        (7=7)
    """
    def __init__(self):
        super(BooleanExpressionList, self).__init__()
        self.clear()
    def clear(self): self.root = None
    def clone(self):
        r = BooleanExpressionList()
        r.assign(self)
        return r
    def assign(self, other):
        import copy
        self.root = copy.deepcopy(other.root)
    def __str__(self): return str(self.root or '')
    def _append(self, booloper, *boolexprs):
        if len(boolexprs) > 0:
            if self.root is None:
                self.root = booloper(*boolexprs)
            else:
                self.root = booloper.combine(self.root, *boolexprs)
    def And(self, *boolexprs): self._append(And, *boolexprs)
    def Or(self, *boolexprs): self._append(Or, *boolexprs)
    def invert(self):
        if self.root is not None: self.root = invert(self.root)

class GroupByList(object):
    """GroupByList

        >>> groupby = GroupByList()
    
        >>> print groupby
        <BLANKLINE>
    
        >>> groupby.append('INVO_DATE')
        >>> groupby.append('ORDER_DATE')
        >>> print groupby
        INVO_DATE,
        ORDER_DATE
    """
    def __init__(self):
        super(GroupByList, self).__init__()
        self.clear()
    def clear(self): self.values = []
    def clone(self):
        r = GroupByList()
        r.assign(self)
        return r
    def assign(self, other): self.values = list(other.values)
    def append(self, value): self.values.append(value)
    def __str__(self):
        return ',\n'.join([str(v) for v in self.values])

class OrderByList(object):
    """OrderByList

        >>> orderby = OrderByList()
    
        >>> print orderby
        <BLANKLINE>
    
        >>> orderby.append('INVO_DATE')
        >>> orderby.append('ORDER_DATE', False)
        >>> orderby.append('LINE_NUMBER', True)
        >>> print orderby
        INVO_DATE,
        ORDER_DATE desc,
        LINE_NUMBER
    """
    def __init__(self):
        super(OrderByList, self).__init__()
        self.clear()
    def clear(self):
        self.values = []
        self.ascendings = []
    def clone(self):
        r = OrderByList()
        r.assign(self)
        return r
    def assign(self, other):
        self.values = list(other.values)
        self.ascendings = list(other.ascendings)
    def append(self, value, ascending=True):
        self.values.append(value)
        self.ascendings.append(ascending)
    def __str__(self):
        def line(value, ascending): return (ascending and str(value)) or (str(value) + ' desc')
        return ',\n'.join([line(v,a) for v,a in zip(self.values, self.ascendings)])

class Function(object):
    def __init__(self, name):
        super(Function, self).__init__()
        self.name = name
    def __call__(self, *args):
        args_text = ', '.join([blanket_as_needed(a) for a in args])
        return '%s(%s)' % (self.name, args_text)

class FunctionFactory(object):
    def __getattr__(self, name): return Function(name)

class Statement(object):
    def __init__(self):
        super(Statement, self).__init__()
        self.func = FunctionFactory()

class BaseJoinList(object):
    def __init__(self):
        super(BaseJoinList, self).__init__()
        self.clear()
    def clear(self):
        self.lefts = []
        self.rights = []
        self.expressions = []
    def clone(self):
        r = type(self)()
        r.assign(self)
        return r
    def assign(self, other):
        self.lefts = list(other.lefts)
        self.rights = list(other.rights)
        self.expressions = list(other.expressions)
    def is_joined(self, left, right): raise NotImplementedError()
    def append(self, left, right, expression):
        if self.is_joined(left, right): raise ValueError('Already joined')
        sources = frozenset([f.source for f in iter_fields(expression)])
        if (len(sources) != 2) or (left not in sources) or (right not in sources):
            raise ValueError('Only expressions of fields of joining sources are allowed')
        self.lefts.append(left)
        self.rights.append(right)
        self.expressions.append(expression)
    def iter_joinings(self, joined): raise NotImplementedError()

class InnerJoinList(BaseJoinList):
    def __init__(self): super(InnerJoinList, self).__init__()
    def is_joined(self, left, right):
        for l,r in zip(self.lefts, self.rights):
            if (l==left) and (r==right): return True
            if (l==right) and (r==left): return True
        return False
    def iter_joinings(self, joined):
        for i in xrange(len(self.lefts)):
            if self.lefts[i]==joined: yield self.rights[i], self.expressions[i]
        for i in xrange(len(self.rights)):
            if self.rights[i]==joined: yield self.lefts[i], self.expressions[i]

class OuterJoinList(BaseJoinList):
    def __init__(self): super(OuterJoinList, self).__init__()
    def is_joined(self, left, right):
        for l,r in zip(self.lefts, self.rights):
            if (l==left) and (r==right): return True
        return False
    def iter_joinings(self, joined):
        for i in xrange(len(self.lefts)):
            if self.lefts[i]==joined: yield self.rights[i], self.expressions[i]

def make_oracle_outer(outer, inner, expression):
    if isinstance(expression, InfixedComparisonExpression) and (not isinstance(expression, OracleOuterDecorator)):
        if (expression.left == outer) and (expression.right == inner): return OracleOuterDecorator(expression, True)
        if (expression.left == inner) and (expression.right == outer): return OracleOuterDecorator(expression, False)
	raise Exception('Not supported expression')
    elif isinstance(expression, InfixedBooleanExpression):
        return type(expression)(*[make_oracle_outer(outer, inner, e) for e in expression.elements])

class BaseSelect(Statement):
    def __init__(self):
        super(BaseSelect, self).__init__()
        self.fields = FieldList()
        self.sources = SourceList()
        self.where = BooleanExpressionList()
        self.groupby = GroupByList()
        self.having = BooleanExpressionList()
        self.orderby = OrderByList()
        self.innerjoins = InnerJoinList()
        self.outerjoins = OuterJoinList()

    def get_from_clause(self): raise NotImplementedError()

    def get_where_clause(self): raise NotImplementedError()

    def __str__(self):
        def section(term, clause):
            if clause:
                return '%s\n%s' % (term, indent(2, clause))
            else:
                return ''
        fields = str(self.fields) or '*'
        froms = section('from', self.get_from_clause())
        where = section('where', self.get_where_clause())
        groupby = section('group by', str(self.groupby))
        having = section('having', str(self.having))
        orderby = section('order by', str(self.orderby))
        return '\n'.join([x for x in ['select', indent(2, fields), froms, where, groupby, having, orderby] if x])

    def join(self, left, right):
        def joiner(*exprs): self.innerjoins.append(left, right, And(*exprs))
        return joiner
    def outer_join(self, left, right):
        def joiner(*exprs): self.outerjoins.append(left, right, And(*exprs))
        return joiner

class StandardSelect(BaseSelect):
    """StandardSelect

        >>> s = StandardSelect()
        >>> ima = s.sources('ima')
        >>> pst = s.sources('pst')
        >>> ima2 = s.sources('ima', 'ima2')
        >>> s.join(ima, pst)(ima.IMA_ItemID == pst.PST_ItemID)
        >>> s.outer_join(ima, ima2)(ima.IMA_ItemID == ima2.IMA_ItemID)
        >>> s.where.And(ima.ItemCost > 100000)
        >>> s.where.And(ima.ItemCost < 200000)
        >>> s.fields.append(ima.IMA_ItemID, 'ID')
        >>> s.fields.append(ima.IMA_ItemCost, 'COST')
        >>> s.fields.append(ima.IMA_ItemName, 'ITEM_NAME')
        >>> s.groupby.append(ima.IMA_ItemID)
        >>> s.groupby.append(ima.IMA_ItemCost)
        >>> s.groupby.append(ima.IMA_ItemName)
        >>> s.having.And(ima.IMA_ItemName.like(strlit('Huh%')))
        >>> s.orderby.append(ima.IMA_ItemName, False)
        >>> s.orderby.append(ima.IMA_ItemCost)
        >>> print s
        select
          ima.IMA_ItemID                                     ID,
          ima.IMA_ItemCost                                   COST,
          ima.IMA_ItemName                                   ITEM_NAME
        from
          ima
            join pst on (ima.IMA_ItemID = pst.PST_ItemID)
            left outer join ima ima2 on (ima.IMA_ItemID = ima2.IMA_ItemID)
        where
          (ima.ItemCost > 100000) and
          (ima.ItemCost < 200000)
        group by
          ima.IMA_ItemID,
          ima.IMA_ItemCost,
          ima.IMA_ItemName
        having
          (ima.IMA_ItemName like 'Huh%')
        order by
          ima.IMA_ItemName desc,
          ima.IMA_ItemCost
    """

    def get_where_clause(self): return str(self.where)
    def get_from_clause(self):
        result = []
        included = []
        for source in self.sources:
            if source not in included:
                queued = [source]
                joinlines = []
                while queued:
                    s = queued.pop(0)
                    if s not in included:
                        included.append(s)
                        for joining, expression in self.innerjoins.iter_joinings(s):
                            if joining not in included:
                                queued.append(joining)
                                joinlines.append('join %s on %s' % (joining.declaration(), str(expression)))
                        for joining, expression in self.outerjoins.iter_joinings(s):
                            if joining not in included:
                                queued.append(joining)
                                joinlines.append('left outer join %s on %s' % (joining.declaration(), str(expression)))
                    included.append(s)
                if result: result[-1] += ','
                result.append(str(source))
                result.extend(['  %s' % x for x in joinlines])
        return '\n'.join(result)

class OracleSelect(BaseSelect):
    """OracleSelect

        >>> s = OracleSelect()
        >>> ima = s.sources('ima')
        >>> pst = s.sources('pst')
        >>> ima2 = s.sources('ima', 'ima2')
        >>> s.join(ima, pst)(ima.IMA_ItemID == pst.PST_ItemID)
        >>> s.outer_join(ima, ima2)(ima.IMA_ItemID == ima2.IMA_ItemID)
        >>> s.where.And(ima.ItemCost > 100000)
        >>> s.where.And(ima.ItemCost < 200000)
        >>> print s
        select
          *
        from
          ima,
          pst,
          ima ima2
        where
          (ima.IMA_ItemID = pst.PST_ItemID) and
          (ima.IMA_ItemID = ima2.IMA_ItemID(+)) and
          (ima.ItemCost > 100000) and
          (ima.ItemCost < 200000)
    """
    def get_where_clause(self):
        inner_exprs = self.innerjoins.expressions
        outer_packs = zip(self.outerjoins.lefts, self.outerjoins.rights, self.outerjoins.expressions)
        outer_exprs = [make_oracle_outer(outer, inner, expr) for outer, inner, expr in outer_packs]
        if self.where.root:
            where_exprs = [self.where.root]
        else:
            where_exprs = []
        return str(And.combine(*(inner_exprs + outer_exprs + where_exprs)))
    
    def get_from_clause(self): return ',\n'.join([source.declaration() for source in self.sources])
    
if __name__ == '__main__':
    try:
        from zope.testing import doctest
    except ImportError:
        import doctest
    doctest.testmod()

This module can make 80% of dynamic sql construction easier and it makes your code be in better factored shape. The module is fully doctested. Sorry if you find the tables and fields' name used in the doctest string is a bit ugly. It's from my current work. I don't name table and fields that way, btw.

2 comments

Mike Hostetler 18 years, 9 months ago  # | flag

SQLObject. for something somewhat similar, check out the SQLObject project:

http://www.sqlobject.org

It's different, because it does all the SQL calls in the background and returns the results as Python objects. Works well if you are using the one of the supported databases. The above is a less db-platform-specific solution.

Patrick Tou 17 years, 6 months ago  # | flag

bug report. While simple, this module mostly serves my purposes. Bug report:

# diff standardselect.py standardselect_orig.py
233c233
&lt;     def __str__(self): return (' %s ' % self.infix).join([str(blanket_as_needed(e)) for e in self.elements if str(e).strip != ""])
---
&gt;     def __str__(self): return (' %s ' % self.infix).join([str(blanket_as_needed(e)) for e in self.elements if e])
877d876
&lt;         &gt;&gt;&gt; s.where.And(ima.ItemCount == 0)
898,899c897
&lt;           (ima.ItemCost &lt; 200000) and
&lt;           (ima.ItemCount = 0)
---
&gt;           (ima.ItemCost &lt; 200000)