Ruby - Implement an SQL server? - sql

Question

I have an application which has a Ruby API. I would like to link to this application from a SQL server system.
Is there a way for me to implement a Ruby SQL server which receives SQL statements and returns the requested data from the applications. Is it then possible to hook into this from an SQL server applications?
E.G.
# request as string like "SELECT * FROM MAIN_TABLE WHERE SOME_COLUMN = <SOME DATA>"
SQLEngine.OnRequest do |request|
Application.RunSQL(request)
end
P.S. I don't have any experience with SQL server, so have no idea how one would go about this...
Note: I'm not asking how I can query an SQL server database, I'm asking how I can implement an SQL server connection.

Answer 1

After some searching I found a few other stack overflow questions about how to make Database Drivers in other languages:
creating a custom odbc driver for application
Implementing a ODBC driver
Creating a custom ODBC driver
Alternatives to writing an ODBC driver
Potentially these will be useful for others going down this road, the most hopeful suggestion is implementing the wire protocol, of which one has been made in python which should be relatively easy to port
import SocketServer
import struct
def char_to_hex(char):
retval = hex(ord(char))
if len(retval) == 4:
return retval[-2:]
else:
assert len(retval) == 3
return "0" + retval[-1]
def str_to_hex(inputstr):
return " ".join(char_to_hex(char) for char in inputstr)
class Handler(SocketServer.BaseRequestHandler):
def handle(self):
print "handle()"
self.read_SSLRequest()
self.send_to_socket("N")
self.read_StartupMessage()
self.send_AuthenticationClearText()
self.read_PasswordMessage()
self.send_AuthenticationOK()
self.send_ReadyForQuery()
self.read_Query()
self.send_queryresult()
def send_queryresult(self):
fieldnames = ['abc', 'def']
HEADERFORMAT = "!cih"
fields = ''.join(self.fieldname_msg(name) for name in fieldnames)
rdheader = struct.pack(HEADERFORMAT, 'T', struct.calcsize(HEADERFORMAT) - 1 + len(fields), len(fieldnames))
self.send_to_socket(rdheader + fields)
rows = [[1, 2], [3, 4]]
DRHEADER = "!cih"
for row in rows:
dr_data = struct.pack("!ii", -1, -1)
dr_header = struct.pack(DRHEADER, 'D', struct.calcsize(DRHEADER) - 1 + len(dr_data), 2)
self.send_to_socket(dr_header + dr_data)
self.send_CommandComplete()
self.send_ReadyForQuery()
def send_CommandComplete(self):
HFMT = "!ci"
msg = "SELECT 2\x00"
self.send_to_socket(struct.pack(HFMT, "C", struct.calcsize(HFMT) - 1 + len(msg)) + msg)
def fieldname_msg(self, name):
tableid = 0
columnid = 0
datatypeid = 23
datatypesize = 4
typemodifier = -1
format_code = 0 # 0=text 1=binary
return name + "\x00" + struct.pack("!ihihih", tableid, columnid, datatypeid, datatypesize, typemodifier, format_code)
def read_socket(self):
print "Trying recv..."
data = self.request.recv(1024)
print "Received {} bytes: {}".format(len(data), repr(data))
print "Hex: {}".format(str_to_hex(data))
return data
def send_to_socket(self, data):
print "Sending {} bytes: {}".format(len(data), repr(data))
print "Hex: {}".format(str_to_hex(data))
return self.request.sendall(data)
def read_Query(self):
data = self.read_socket()
msgident, msglen = struct.unpack("!ci", data[0:5])
assert msgident == "Q"
print data[5:]
def send_ReadyForQuery(self):
self.send_to_socket(struct.pack("!cic", 'Z', 5, 'I'))
def read_PasswordMessage(self):
data = self.read_socket()
b, msglen = struct.unpack("!ci", data[0:5])
assert b == "p"
print "Password: {}".format(data[5:])
def read_SSLRequest(self):
data = self.read_socket()
msglen, sslcode = struct.unpack("!ii", data)
assert msglen == 8
assert sslcode == 80877103
def read_StartupMessage(self):
data = self.read_socket()
msglen, protoversion = struct.unpack("!ii", data[0:8])
print "msglen: {}, protoversion: {}".format(msglen, protoversion)
assert msglen == len(data)
parameters_string = data[8:]
print parameters_string.split('\x00')
def send_AuthenticationOK(self):
self.send_to_socket(struct.pack("!cii", 'R', 8, 0))
def send_AuthenticationClearText(self):
self.send_to_socket(struct.pack("!cii", 'R', 8, 3))
if __name__ == "__main__":
server = SocketServer.TCPServer(("localhost", 9876), Handler)
try:
server.serve_forever()
except:
server.shutdown()

Answer 2

Every programming language – including Ruby – supplies packages which implement interfaces to various SQL servers.
Start here: Ruby database access.