MSSQL2008 – Pyodbc – Previous SQL was not a query

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!

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.

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(...)

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.

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.

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.

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

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.

I think the root cause of the issue described above might be related with the fact that you receive the same error message when you execute for example a DELETE query which will not return a result. So if you run

 result = cursor.fetchall()

you get this error, because a DELETE operation by definition does not return anything. Try to catch the exception as recommended here: How to check if a result set is empty?

Every statement in a script could produce some output either as a dataset or/and as a message.

select 1 as id

produce

id
-----------
1

(1 row affected)

Last line above is "messages". If I run cursor.fetchall() on this I will get a result back without any errors.

But if my query is an insert .. into .. or a call to stored procedure that does not return dataset, then fetchall() on it would give me an error.

There is a way to know if fetching would give me pyodbc.ProgrammingError:

if cursor.description:
    cursor.fetchall()

cursor.description has all the field definitions for your dataset It would be None if there is nothing there.

If I have multiple statements in a script I can iterate over datasets with nextset(). Here is a way to read full response:

def print_current_results(cursor):
    if cursor.messages:
        print(cursor.messages)
    if cursor.description:
        print(cursor.fetchall())

cursor.execute(some_script)
print_current_results(cursor)
while cursor.nextset():
   print_current_results(cursor)

To reduce number of loops and minimize the overall output, use SET NOCOUNT ON that is mentioned in almost all other answers. If sql statement has not produced dataset or message then it skipped in output and this is how you can do just cursor.fetchall() instead of above much longer script