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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 Literal, CaselessLiteral, Word, delimitedList, Optional, \
Combine, Group, alphas, nums, alphanums, ParseException, Forward, oneOf, quotedString, \
ZeroOrMore, restOfLine, CaselessKeyword, pyparsing_common
# define SQL tokens
selectStmt = Forward()
SELECT, FROM, WHERE = map(CaselessKeyword, "select from where".split())
ident = Word( alphas, alphanums + "_$" ).setName("identifier")
columnName = delimitedList(ident, ".", combine=True).setName("column name")
columnName.addParseAction(pyparsing_common.upcaseTokens)
columnNameList = Group( delimitedList(columnName))
tableName = delimitedList(ident, ".", combine=True).setName("table name")
tableName.addParseAction(pyparsing_common.upcaseTokens)
tableNameList = Group(delimitedList(tableName))
whereExpression = Forward()
and_, or_, in_ = map(CaselessKeyword, "and or in".split())
binop = oneOf("= != < > >= <= eq ne lt le gt ge", caseless=True)
realNum = pyparsing_common.real()
intNum = pyparsing_common.signed_integer()
columnRval = realNum | intNum | quotedString | columnName # need to add support for alg expressions
whereCondition = Group(
( columnName + binop + columnRval ) |
( columnName + in_ + "(" + delimitedList( columnRval ) + ")" ) |
( columnName + in_ + "(" + selectStmt + ")" ) |
( "(" + whereExpression + ")" )
)
whereExpression << whereCondition + ZeroOrMore( ( and_ | or_ ) + whereExpression )
# define the grammar
selectStmt <<= (SELECT + ('*' | columnNameList)("columns") +
FROM + tableNameList( "tables" ) +
Optional(Group(WHERE + whereExpression), "")("where"))
simpleSQL = selectStmt
# define Oracle comment format, and ignore them
oracleSqlComment = "--" + restOfLine
simpleSQL.ignore( oracleSqlComment )
if __name__ == "__main__":
simpleSQL.runTests("""\
# 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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