python - MSSQL2008 - Pyodbc - Previous SQL was not a query

Question

I can't figure out what's wrong with the following code, The syntax IS ok (checked with SQL Management Studio), i have access as i should so that works too.. but for some reason as soon as i try to create a table via PyODBC then it stops working.

import pyodbc

def SQL(QUERY, target = '...', DB = '...'):
    cnxn = pyodbc.connect('DRIVER={SQL Server};SERVER=' + target + DB+';UID=user;PWD=pass')
    cursor = cnxn.cursor()
    cursor.execute(QUERY)
    cpn = []

    for row in cursor:
        cpn.append(row)
    return cpn

print SQL("CREATE TABLE dbo.Approvals (ID SMALLINT NOT NULL IDENTITY PRIMARY KEY, HostName char(120));")

It fails with:

Traceback (most recent call last):
  File "test_sql.py", line 25, in <module>
    print SQL("CREATE TABLE dbo.Approvals (ID SMALLINT NOT NULL IDENTITY PRIMARY KEY, HostName char(120));")
  File "test_sql.py", line 20, in SQL
    for row in cursor:
pyodbc.ProgrammingError: No results.  Previous SQL was not a query.

Anyone have any idea to why this is? I got a "SQL Server" driver installed (it's default), running Windows 7 against a Windows 2008 SQL Server environment (Not a express database).

Answer 1

Just in case some lonely net nomad comes across this issue, the solution by Torxed didn't work for me. But the following worked for me.

I was calling an SP which inserts some values into a table and then returns some data back. Just add the following to the SP :

SET NOCOUNT ON

It'll work just fine :)

The Python code :

    query = "exec dbo.get_process_id " + str(provider_id) + ", 0"
    cursor.execute(query)

    row = cursor.fetchone()
    process_id = row[0]

The SP :

USE [DBNAME]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER procedure [dbo].[GET_PROCESS_ID](
    @PROVIDER_ID INT,
    @PROCESS_ID INT OUTPUT
)
AS
BEGIN
    SET NOCOUNT ON
    INSERT INTO processes(provider_id) values(@PROVIDER_ID)
    SET @PROCESS_ID= SCOPE_IDENTITY()
    SELECT @PROCESS_ID AS PROCESS_ID
END

Answer 2

Using the "SET NOCOUNT ON" value at the top of the script will not always be sufficient to solve the problem.

In my case, it was also necessary to remove this line:

Use DatabaseName;

Database was SQL Server 2012, Python 3.7, SQL Alchemy 1.3.8

Hope this helps somebody.

Answer 3

I got this because I was reusing a cursor that I was looping over:

rows = cursor.execute(...)
for row in rows:
    # run query that returns nothing
    cursor.execute(...)
    # next iteration of this loop will throw 'Previous SQL' error when it tries to fetch next row because we re-used the cursor with a query that returned nothing

Use 2 different cursors instead

rows = cursor1.execute(...)
for row in rows:
    cursor2.execute(...)

or get all results of the first cursor before using it again:

Use 2 different cursors instead

rows = cursor.execute(...)
for row in list(rows):
    cursor.execute(...)

Answer 4

As others covered, SET NOCOUNT ON will take care of extra resultsets inside a stored procedure, however other things can also cause extra output that NOCOUNT will not prevent (and pyodbc will see as a resultset) such as forgetting to remove a print statement after debugging your stored procedure.

Answer 5

As Travis and others have mentioned, other things can also cause extra output that SET NOCOUNT ON will not prevent.

I had SET NOCOUNT ON at the start of my procedure but was receiving warning messages in my results set.

I set ansi warnings off at the beginning of my script in order to remove the error messages.

SET ANSI_WARNINGS OFF

Hopefully this helps someone.

Answer 6

In case your SQL is not Stored Proc.

usage of 'xyz != NULL' in query, will give the same error i.e. "pyodbc.ProgrammingError: No results. Previous SQL was not a query."

Use 'is not null' instead.

Answer 7

If your stored procedure calls RAISERROR, pyodbc may create a set for that message.

CREATE PROCEDURE some_sp
AS
BEGIN
    RAISERROR ('Some error!', 1, 1) WITH NOWAIT
    RETURN 777
END

In python, you need to skip the first sets until you find one containing some results (see https://github.com/mkleehammer/pyodbc/issues/673#issuecomment-631206107 for details).

sql = """
    SET NOCOUNT ON;
    SET ANSI_WARNINGS OFF;
    DECLARE @ret int;
    EXEC @ret = some_sp;
    SELECT @ret as ret;
    """
cursor = con.cursor()
cursor.execute(sql)

rows = None
#this section will only return the last result from the query
while cursor.nextset():
    try:
        rows = cursor.fetchall()
    except Exception as e:
        print("Skipping non rs message: {}".format(e))
    continue

row = rows[0]
print(row[0])  # 777.

Answer 8

First off:

if you're running a Windows SQL Server 2008, use the "Native Client" that is included with the installation of the SQL software (it gets installed with the database and Toolkits so you need to install the SQL Management applicaton from Microsoft)

Secondly: Use "Trusted_Connection=yes" in your SQL connection statement:

cnxn = pyodbc.connect('DRIVER={SQL Server Native Client 10.0};SERVER=ServerAddress;DATABASE=my_db;Trusted_Connection=yes')

This should do the trick!

Answer 9

I have solved this problem by splitting the use database and sql query into two execute statements.