58 lines
2.0 KiB
Python
58 lines
2.0 KiB
Python
from django.db.models.sql import compiler
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class SQLCompiler(compiler.SQLCompiler):
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def as_sql(self, with_limits=True, with_col_aliases=False, subquery=False):
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"""
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Creates the SQL for this query. Returns the SQL string and list
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of parameters. This is overridden from the original Query class
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to handle the additional SQL Oracle requires to emulate LIMIT
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and OFFSET.
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If 'with_limits' is False, any limit/offset information is not
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included in the query.
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"""
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# The `do_offset` flag indicates whether we need to construct
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# the SQL needed to use limit/offset with Oracle.
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do_offset = with_limits and (self.query.high_mark is not None or self.query.low_mark)
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if not do_offset:
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sql, params = super(SQLCompiler, self).as_sql(
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with_limits=False,
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with_col_aliases=with_col_aliases,
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subquery=subquery,
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)
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else:
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sql, params = super(SQLCompiler, self).as_sql(
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with_limits=False,
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with_col_aliases=True,
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subquery=subquery,
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)
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# Wrap the base query in an outer SELECT * with boundaries on
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# the "_RN" column. This is the canonical way to emulate LIMIT
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# and OFFSET on Oracle.
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high_where = ''
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if self.query.high_mark is not None:
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high_where = 'WHERE ROWNUM <= %d' % (self.query.high_mark,)
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sql = (
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'SELECT * FROM (SELECT "_SUB".*, ROWNUM AS "_RN" FROM (%s) '
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'"_SUB" %s) WHERE "_RN" > %d' % (sql, high_where, self.query.low_mark)
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)
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return sql, params
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class SQLInsertCompiler(compiler.SQLInsertCompiler, SQLCompiler):
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pass
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class SQLDeleteCompiler(compiler.SQLDeleteCompiler, SQLCompiler):
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pass
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class SQLUpdateCompiler(compiler.SQLUpdateCompiler, SQLCompiler):
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pass
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class SQLAggregateCompiler(compiler.SQLAggregateCompiler, SQLCompiler):
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pass
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