Revision 2187
Added by Aaron Marcuse-Kubitza about 12 years ago
| sql.py | ||
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join_using = object() # tells mk_select() to join the column with USING |
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join_not_equal = object() # tells mk_select() to join the column with !=
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filter_out = object() # tells mk_select() to filter out rows that match the join
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def mk_select(db, tables, fields=None, conds=None, limit=None, start=None, |
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order_by=order_by_pkey, table_is_esc=False): |
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''' |
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@param tables The single table to select from, or a list of tables to join |
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together: [table0, (table1, dict(right_col=left_col, ...)), ...] |
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together: [table0, (table1, joins), ...] |
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joins has the format: dict(right_col=left_col, ...) |
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* if left_col is join_using, left_col is set to right_col |
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* if left_col is filter_out, the tables are LEFT JOINed together and the |
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query is filtered by `right_col IS NULL` (indicating no match) |
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@param fields Use None to select all fields in the table |
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@param table_is_esc Whether the table name has already been escaped |
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@return tuple(query, params) |
| ... | ... | |
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def cond(entry): |
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'''Parses conditions''' |
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col, value = entry |
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cond_ = esc_name_(col)+' '
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cond_ = parse_col(col)+' '
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if value == None: cond_ += 'IS' |
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else: cond_ += '=' |
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cond_ += ' %s' |
| ... | ... | |
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left_table = table0 |
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for table, joins in tables: |
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if not table_is_esc: table = esc_name_(table) |
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query += ' JOIN '+table |
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left_join_ref = [False] |
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def join(entry): |
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'''Parses non-USING joins''' |
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right_col, left_col = entry |
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negative = False |
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# Parse special values |
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if left_col == None: left_col = (left_col,) |
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# for None values, tuple is optional |
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elif left_col == join_using: left_col = right_col |
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elif left_col == join_not_equal:
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elif left_col == filter_out:
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left_col = right_col |
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negative = True |
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left_join_ref[0] = True |
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conds[(table, right_col)] = None # filter query by no match |
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# Create SQL |
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right_col = table+'.'+esc_name_(right_col) |
| ... | ... | |
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sql_ += ('= '+left_col+' OR ('+right_col+' IS NULL AND '
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+left_col+' IS NULL)') |
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if negative: sql_ = 'NOT ('+sql_+')'
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return sql_ |
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# Create join condition and determine join type |
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if reduce(operator.and_, (v == join_using for v in joins.itervalues())): |
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# all cols w/ USING, so can use simpler USING syntax |
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query += ' USING ('+(', '.join(joins.iterkeys()))+')'
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else: query += ' ON '+(' AND '.join(map(join, joins.iteritems())))
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join_cond = 'USING ('+(', '.join(joins.iterkeys()))+')'
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else: join_cond = 'ON '+(' AND '.join(map(join, joins.iteritems())))
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# Create join |
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if left_join_ref[0]: query += ' LEFT' |
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query += ' JOIN '+table+' '+join_cond |
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left_table = table |
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missing = True |
Also available in: Unified diff
sql.py: mk_select(): joins: Fixed bug where join_not_equal did not do what it was designed for, which is filtering out matches of the join condition (before the bug fix, it effectively did a cross join with matching rows excluded, causing duplication of rows). Renamed join_not_equal to filter_out to reflect its intended use. Support table-scoped column names in the WHERE conds list.