I am making a python GUI that will look up the the status of a helpdesk ticket in a MySQL database. I connected python to an existing MySQL database with SQLAlchemy using the code below.
conn = mysql.connector.connect(user='root',
password='stuff',host='127.0.0.1',
database='mydb')
c = conn.cursor()
I only need access to one of the columns, ticket_id, in a table called tickets. Basically I want to do this:
SELECT ticket_status FROM tickets WHERE ticket_id = 123;
What would be simplest way to do this?
The following code should work at fetching a single value. If you realize later you need to fetch more than one value you can change fetchone() to fetchall()
try:
sql = '''
SELECT ticket_status FROM tickets WHERE ticket_id = 123
'''
c.execute(sql)
result = c.fetchone()
except Exception as e:
raise Exception(e)
Related
I have parameterized queries with f strings such that the queries will select some data from a series of tables and joins, and I want to insert the resulting set of data into another pre-created table (tables been designed to house these results).
Python executes the code but the query results never show up in my table.
Assuming target_table is already created in singlestore database:
qry_load = 'insert into target_table select * from some_tables'
conn = engine.connect()
trans = conn.begin()
try:
conn.execute(qry_load)
trans.commit()
except:
trans.rollback()
raise
The code executes and acts as if all is ok, but the data never shows up in the target table.
How do I see what singlestore is passing back to better debug what is happening within the database?
Just replace begin() with cursor() function:
conn = engine.connect()
trans = conn.cursor()
If not resolved
1- Verify structure of source and destination tables if they are same or not.
2- remove try ,except and rollback() block so you can know the actual error.
Ex.
qry_load = 'insert into target_table select * from some_tables'
conn = engine.connect()
trans = conn.cursor()
conn.execute(qry_load)
trans.commit()
Can the cursor.execute call below execute multiple SQL queries in one go?
cursor.execute("use testdb;CREATE USER MyLogin")
I don't have python setup yet but want to know if above form is supported by cursor.execute?
import pyodbc
# Some other example server values are
# server = 'localhost\sqlexpress' # for a named instance
# server = 'myserver,port' # to specify an alternate port
server = 'tcp:myserver.database.windows.net'
database = 'mydb'
username = 'myusername'
password = 'mypassword'
cnxn = pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER='+server+';DATABASE='+database+';UID='+username+';PWD='+ password)
cursor = cnxn.cursor()
#Sample select query
cursor.execute("SELECT ##version;")
row = cursor.fetchone()
while row:
print(row[0])
row = cursor.fetchone()
Multiple SQL statements in a single string is often referred to as an "anonymous code block".
There is nothing in pyodbc (or pypyodbc) to prevent you from passing a string containing an anonymous code block to the Cursor.execute() method. They simply pass the string to the ODBC Driver Manager (DM) which in turn passes it to the ODBC Driver.
However, not all ODBC drivers accept anonymous code blocks by default. Some databases default to allowing only a single SQL statement per .execute() to protect us from SQL injection issues.
For example, MySQL/Connector ODBC defaults MULTI_STATEMENTS to 0 (off) so if you want to run an anonymous code block you will have to include MULTI_STATEMENTS=1 in your connection string.
Note also that changing the current database by including a USE … statement in an anonymous code block can sometimes cause problems because the database context changes in the middle of a transaction. It is often better to execute a USE … statement by itself and then continue executing other SQL statements.
Yes, it is possible.
operation = 'SELECT 1; INSERT INTO t1 VALUES (); SELECT 2'
for result in cursor.execute(operation, multi=True):
But it is not a comprehensive solution. For example, in queries with two selections, you have problems.
Consider that two types of answers must be fetch all in the cursor!
So the best solution is to break the query to sub queries and do your work step by step.
for example :
s = "USE some_db; SELECT * FROM some_table;"
s = filter(None, s.split(';'))
for i in s:
cur.execute(i.strip() + ';')
in the pyodbc documentation should give you the example your looking for. more over in the GitHub wiki: https://github.com/mkleehammer/pyodbc/wiki/Objects#cursors
you can see an example here:
cnxn = pyodbc.connect(...)
cursor = cnxn.cursor()
cursor.execute("""
select user_id, last_logon
from users
where last_logon > ?
and user_type <> 'admin'
""", twoweeks)
rows = cursor.fetchall()
for row in rows:
print('user %s logged on at %s' % (row.user_id, row.last_logon))
from this example and exploring the code, I would say your next step is testing a multi cursor.execute("<your_sql_Querie>").
if this test works, maybe try and create a CLASS then create instances of that class for each query you want to run.
This would be the basic evolution of a developers effort of reproducing documentation...hope this helps you :)
Yes, you can results for multiple queries by using the nextset() method...
query = "select * from Table1; select * from Table2"
cursor = connection.cursor()
cursor.execute(query)
table1 = cursor.fetchall()
cursor.nextset()
table2 = cursor.fetchall()
The code explains it... cursors return result "sets", which you can move between using the nextset() method.
I am accessing a MS Access Database in Python 3.6 using pyodbc library. I can read a table, no problems. The I created a simple table (Employee). I inserted records. I was able to fetch the records too by reading the table, no problems.
I also listed the tables in the MS Access DB. Employee table shows in the list.
But when I open up the MS Access Database, I do not find the table. I changed MS Access DB to show hidden and system objects. Employee table doesn't show up.
What am I doing wrong?
Thanks
Here is the code:
import pyodbc
db_file = r'''C:\TickData2018\StooqDataAnalysis.accdb'''
user = 'admin'
password = ''
odbc_conn_str = 'DRIVER={Microsoft Access Driver (*.accdb)};DBQ=%s;UID=%s;PWD=%s' %\
(db_file, user, password)
# Or, for newer versions of the Access drivers:
odbc_conn_str = 'DRIVER={Microsoft Access Driver (*.mdb, *.accdb)};DBQ=%s;UID=%s;PWD=%s' %\
(db_file, user, password)
conn = pyodbc.connect(odbc_conn_str)
print("connection made")
c = conn.cursor()
c.execute("SELECT * FROM 5MtsBaseForAnalysisSorted")
list1 = c.fetchmany(2)
print(list1[0][0])
print(list1[0][1])
print(list1[0][2])
try:
c.execute("""CREATE TABLE employee(
first text,
last text,
pay integer
);""")
except Exception as e:
print(e)
conn.commit
c.execute("INSERT INTO employee VALUES ('Krishna', 'Sundar', 50000)")
c.execute("INSERT INTO employee VALUES ('Divya', 'Sundar', 70000)")
c.execute("INSERT INTO employee VALUES ('Panka', 'Sundar', 70000)")
conn.commit
c.execute("SELECT * FROM employee")
print(c.fetchall())
c.tables()
rows = c.fetchall()
for row in rows:
print(row)
c.close()
del c
conn.close()
This is a general Python object model where you need to call the actual function and not its bounded name. Specifically, your commit lines are not correct where
conn.commit
Should be with open/close parentheses:
conn.commit()
Another way to see the difference is by reviewing the object's type:
type(conn.commit)
# <built-in method commit of pyodbc.Connection object at 0x000000000B772E40>
type(conn.commit())
# NoneType
I did reproduce your issue with exact code and adding parentheses resolved the issue.
An additional solution to manually committing is to set autocommit = True when the connection instance is created.
Eg:
conn = pyodbc.connect(odbc_conn_str, autocommit = True)
I want to get a value from a database table using python.
I am sending a query and getting value like this:
conn = pymysql.connect(rds_host, user=name, passwd=password,db=db_name, connect_timeout=10)
with conn.cursor() as cur:
cur.execute("SELECT id FROM user_details WHERE email='{}'".format(email)
for row in cur:
id = row[0]
Is there a way to get the value without using for loop.
Couldn't find the doc ?
https://pymysql.readthedocs.io/en/latest/modules/cursors.html#pymysql.cursors.Cursor.fetchone
cursor.fetchone()
Fetch the next row
Also, you definitly DONT want to use string formatting to build your queries (unless you're ok to have your app wide opened to sql injections of couse). You want to use prepared queries instead:
cur.execute("SELECT id FROM user_details WHERE email=?", [email,])
I'm new to mySQL and Python.
I have code to insert data from Python into mySQL,
conn = MySQLdb.connect(host="localhost", user="root", passwd="kokoblack", db="mydb")
for i in range(0,len(allnames)):
try:
query = "INSERT INTO resumes (applicant, jobtitle, lastworkdate, lastupdate, url) values ("
query = query + "'"+allnames[i]+"'," +"'"+alltitles[i]+"',"+ "'"+alldates[i]+"'," + "'"+allupdates[i]+"'," + "'"+alllinks[i]+"')"
x = conn.cursor()
x.execute(query)
row = x.fetchall()
except:
print "error"
It seems to be working fine, because "error" never appears. Instead, many rows of "1L" appear in my Python shell. However, when I go to MySQL, the "resumes" table in "mydb" remains completely empty.
I have no idea what could be wrong, could it be that I am not connected to MySQL's server properly when I'm viewing the table in MySQL? Help please.
(I only use import MySQLdb, is that enough?)
use commit to commit the changes that you have done
MySQLdb has autocommit off by default, which may be confusing at first
You could do commit like this
conn.commit()
or
conn.autocommit(True) Right after the connection is created with the DB