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# simpleSQL.py
#
# simple demo of using the parsing library to do simple-minded SQL parsing
# could be extended to include where clauses etc.
#
# Copyright (c) 2003,2016, Paul McGuire
#
from pyparsing import (
Word,
DelimitedList,
Optional,
Group,
alphas,
alphanums,
Forward,
one_of,
quoted_string,
infix_notation,
OpAssoc,
rest_of_line,
CaselessKeyword,
ParserElement,
pyparsing_common as ppc,
)
ParserElement.enable_packrat()
# define SQL tokens
selectStmt = Forward()
SELECT, FROM, WHERE, AND, OR, IN, IS, NOT, NULL = map(
CaselessKeyword, "select from where and or in is not null".split()
)
NOT_NULL = NOT + NULL
ident = Word(alphas, alphanums + "_$").set_name("identifier")
columnName = DelimitedList(ident, ".", combine=True).set_name("column name")
columnName.add_parse_action(ppc.upcase_tokens)
columnNameList = Group(DelimitedList(columnName).set_name("column_list"))
tableName = DelimitedList(ident, ".", combine=True).set_name("table name")
tableName.add_parse_action(ppc.upcase_tokens)
tableNameList = Group(DelimitedList(tableName).set_name("table_list"))
binop = one_of("= != < > >= <= eq ne lt le gt ge", caseless=True).set_name("binop")
realNum = ppc.real().set_name("real number")
intNum = ppc.signed_integer()
columnRval = (
realNum | intNum | quoted_string | columnName
).set_name("column_rvalue") # need to add support for alg expressions
whereCondition = Group(
(columnName + binop + columnRval)
| (columnName + IN + Group("(" + DelimitedList(columnRval).set_name("in_values_list") + ")"))
| (columnName + IN + Group("(" + selectStmt + ")"))
| (columnName + IS + (NULL | NOT_NULL))
).set_name("where_condition")
whereExpression = infix_notation(
whereCondition,
[
(NOT, 1, OpAssoc.RIGHT),
(AND, 2, OpAssoc.LEFT),
(OR, 2, OpAssoc.LEFT),
],
).set_name("where_expression")
# define the grammar
selectStmt <<= (
SELECT
+ ("*" | columnNameList)("columns")
+ FROM
+ tableNameList("tables")
+ Optional(Group(WHERE + whereExpression), "")("where")
).set_name("select_statement")
simpleSQL = selectStmt
# define Oracle comment format, and ignore them
oracleSqlComment = "--" + rest_of_line
simpleSQL.ignore(oracleSqlComment)
if __name__ == "__main__":
simpleSQL.run_tests(
"""\
# multiple tables
SELECT * from XYZZY, ABC
# dotted table name
select * from SYS.XYZZY
Select A from Sys.dual
Select A,B,C from Sys.dual
Select A, B, C from Sys.dual, Table2
# FAIL - invalid SELECT keyword
Xelect A, B, C from Sys.dual
# FAIL - invalid FROM keyword
Select A, B, C frox Sys.dual
# FAIL - incomplete statement
Select
# FAIL - incomplete statement
Select * from
# FAIL - invalid column
Select &&& frox Sys.dual
# where clause
Select A from Sys.dual where a in ('RED','GREEN','BLUE')
# compound where clause
Select A from Sys.dual where a in ('RED','GREEN','BLUE') and b in (10,20,30)
# where clause with comparison operator
Select A,b from table1,table2 where table1.id eq table2.id
"""
)
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