i created 2 function in python

• connect to db and assign it dataframe
• get a unique list of selected column

but once i tried it crash and display the below error:

UnboundLocalError: local variable ‘df’ referenced before assignment
if df is not None:

def connect_db():
    # try:
    con = pyodbc.connect(
        driver="ODBC Driver 17 for SQL Server",
        
        Server = "127.0.0.1",# localhost
        
        DATABASE="person",
        UID="test",
        PWD="test",
    )
    cursor = con.cursor()
    df = pd.read_sql_query('''select m.ID,
                        m.name,
                        m.nickname,
                        m.mother_name,
                        m.birthdate
                        from [person].[dbo].[info] m 
              ''',con)
    return con

def get_name(con,df):
    query_name = df.name.drop_duplicates()
    return query_name

def main():
   Connect_db()
   if df is not None:
     st.write(df)
   list_name = get_name(con,df)

what i am doing wrong?

i appreciate help.