How do you get output parameters from a stored pro

Question

I've googled around a bit, but maybe I didn't put the correct magik incantation into the search box.

Does anyone know how to get output parameters from a stored procedure in Python? I'm using pymssql to call a stored procedure, and I'm not sure of the correct syntax to get the output parameter back. I don't think I can use any other db modules since I'm running this from a Linux box to connect to a mssql database on a MS Server.

import pymssql

con = pymssql.connect(host='xxxxx',user='xxxx',password='xxxxx',database='xxxxx')

cur = con.cursor()

query = "EXECUTE blah blah blah"

cur.execute(query)
con.commit()
con.close()

Answer 1

You might also look at using SELECT rather than EXECUTE. EXECUTE is (iirc) basically a SELECT that doesn't actually fetch anything (, just makes side-effects happen).

Answer 2

I'm not a python expert but after a brief perusing of the DB-API 2.0 I believe you should use the "callproc" method of the cursor like this:

cur.callproc('my_stored_proc', (first_param, second_param, an_out_param))

Then you'll have the result in the returned value (of the out param) in the "an_out_param" variable.

Answer 3

If you make your procedure produce a table, you can use that result as a substitute for out params.

So instead of:

CREATE PROCEDURE Foo (@Bar INT OUT, @Baz INT OUT) AS
BEGIN
   /* Stuff happens here */
   RETURN 0
END

do

CREATE PROCEDURE Foo (@Bar INT, @Baz INT) AS
BEGIN
   /* Stuff happens here */
   SELECT @Bar Bar, @Baz Baz
   RETURN 0
END

Answer 4

I was able to get an output value from a SQL stored procedure using Python. I could not find good help getting the output values in Python. I figured out the Python syntax myself, so I suspect this is worth posting here:

import sys, string, os, shutil, arcgisscripting
from win32com.client import Dispatch
from adoconstants import *

#skip ahead to the important stuff

conn = Dispatch('ADODB.Connection')
conn.ConnectionString = "Provider=sqloledb.1; Data Source=NT38; Integrated Security = SSPI;database=UtilityTicket"
conn.Open()

#Target Procedure Example: EXEC TicketNumExists @ticketNum = 8386998, @exists output

Cmd = Dispatch('ADODB.Command')
Cmd.ActiveConnection = conn

Cmd.CommandType = adCmdStoredProc
Cmd.CommandText = "TicketNumExists"

Param1 = Cmd.CreateParameter('@ticketNum', adInteger, adParamInput)
Param1.Value = str(TicketNumber)
Param2 = Cmd.CreateParameter('@exists', adInteger, adParamOutput)

Cmd.Parameters.Append(Param1)
Cmd.Parameters.Append(Param2)

Cmd.Execute()

Answer = Cmd.Parameters('@exists').Value

Answer 5

Here's how I did it, the key is to declare output parameter first:

import cx_Oracle as Oracle

conn = Oracle.connect('xxxxxxxx')
cur = conn.cursor()

idd = cur.var(Oracle.NUMBER)
cur.execute('begin :idd := seq_inv_turnover_id.nextval; end;', (idd,))
print(idd.getvalue())

Answer 6

2016 update (callproc support in pymssql 2.x)

pymssql v2.x offers limited support for callproc. It supports OUTPUT parameters using the pymssql.output() parameter syntax. Note, however, that OUTPUT parameters can only be retrieved with callproc if the stored procedure does not also return a result set. That issue is discussed on GitHub here.

For stored procedures that do not return a result set

Given the T-SQL stored procedure

CREATE PROCEDURE [dbo].[myDoubler] 
    @in int = 0, 
    @out int OUTPUT
AS
BEGIN
    SET NOCOUNT ON;
    SELECT @out = @in * 2;
END

the Python code

import pymssql
conn = pymssql.connect(
    host=r'localhost:49242',
    database='myDb',
    autocommit=True
    )
crsr = conn.cursor()

sql = "dbo.myDoubler"
params = (3, pymssql.output(int, 0))
foo = crsr.callproc(sql, params)
print(foo)
conn.close()

produces the following output

(3, 6)

Notice that callproc returns the parameter tuple with the OUTPUT parameter value assigned by the stored procedure (foo[1] in this case).

For stored procedures that return a result set

If the stored procedure returns one or more result sets and also returns output parameters, we need to use an anonymous code block to retrieve the output parameter value(s):

Stored Procedure:

ALTER PROCEDURE [dbo].[myDoubler] 
    @in int = 0, 
    @out int OUTPUT
AS
BEGIN
    SET NOCOUNT ON;
    SELECT @out = @in * 2;
    -- now let's return a result set, too
    SELECT 'foo' AS thing UNION ALL SELECT 'bar' AS thing;
END

Python code:

sql = """\
DECLARE @out_value INT;
EXEC dbo.myDoubler @in = %s, @out = @out_value OUTPUT;
SELECT @out_value AS out_value;
"""
params = (3,)
crsr.execute(sql, params)
rows = crsr.fetchall()
while rows:
    print(rows)
    if crsr.nextset():
        rows = crsr.fetchall()
    else:
        rows = None

Result:

[('foo',), ('bar',)]
[(6,)]