Trying to delete some of the table entries by using pyodbc in database results in nothing happening. I know for sure that database connection is working as intended, can select data. Perhaps any suggestions what could be the cause?
get_user_id = conn.cursor()
get_user_id.execute('''
SELECT b.UserId
FROM Bindery b
INNER JOIN ActiveUser au
ON au.Id = b.UserId
WHERE au.UserId = ?
''', user_to_kick)
id_list = [id[0] for id in get_user_id.fetchall()]
delete_user = conn.cursor()
#delete from bindery first
delete_user.execute('''
DELETE FROM Bindery
WHERE UserId in (?)
''', id_list)
conn.commit
#delete from active user list
delete_user.execute('''
DELETE FROM ActiveUser
WHERE UserId = ?
''', user_to_kick)
conn.commit
delete_user.close()
conn.close
This is a code block that should imo trigger the delete query, but nothing happens. Select query does indeed get the data.
UPDATE:
After some adjustments and passing list as a parameter fixed, the delete query now indeed works as intended.
get_user_id = conn.cursor()
get_user_id.execute('''
SELECT b.UserId
FROM Bindery b
INNER JOIN ActiveUser au
ON au.Id = b.UserId
WHERE au.UserId = ?
''', user_to_kick)
id_list = [id[0] for id in get_user_id.fetchall()]
placeholders = ", ".join(["?"] * len(id_list))
sql = 'DELETE FROM Bindery\
WHERE UserId in (%s)' % placeholders
delete_user = conn.cursor()
#delete from bindery first
delete_user.execute(sql, id_list)
conn.commit()
#delete from active user list
delete_user.execute('''
DELETE FROM ActiveUser
WHERE UserId = ?
''', user_to_kick)
conn.commit()
get_user_id.close()
delete_user.close()
conn.close()
Related
I have a doubt about python and sqlite3.
import sqlite3
conna= sqlite3.connect('db_a')
a = conna.cursor()
connb= sqlite3.connect('db_b')
b = conna.cursor()
I don't know how to ask the relational question between banks, can someone instruct me?
I don't want to use DEF, just the SELECT code for a variable to assume
query = """SELECT COL1 FROM TABLE1.DB_A WHERE NOT EXISTS (SELECT COL1 FROM TABLE2.DB_B WHERE COL1.TABLE2.DE_B = COL1.TABLE1.DE_A)"""
cursor.execute(query)
records = cursor.fetchall()
for row in records:
print(row[0])
Can someone help me?
If the tables exist in different databases you need the ATTACH DATABASE statement to use the 2nd database with the connection object that you connect to the 1st database:
import sqlite3
conn = sqlite3.connect('db_a')
cursor = conn.cursor()
attach = "ATTACH DATABASE 'db_b' AS db_b;"
cursor.execute(attach)
query = """
SELECT t1.COL1
FROM TABLE1 AS t1
WHERE NOT EXISTS (
SELECT t2.COL1
FROM db_b.TABLE2 AS t2
WHERE t2.COL1 = t1.COL1
)
"""
cursor.execute(query)
records = cursor.fetchall()
for row in records:
print(row[0])
detach = "DETACH DATABASE db_b;"
cursor.execute(detach)
Also, instead of EXISTS you could use EXCEPT with the difference being that EXCEPT returns only distinct results:
query = """
SELECT COL1 FROM TABLE1
EXCEPT
SELECT COL1 FROM db_b.TABLE2
"""
I am running 3 consecutive and dependent SQL queries and I am wondering if my code could be more efficient. I had to create 3 separate cursors to execute my method. What can I do to make it more efficient?
What I am doing in that method is:
Insert a new contributor in my contributors table based on the values send on the form
Get the primary key of that new contribution which is it's contributor_id
Insert a new question on the questions table and the foreign key of that table is the contributor_id from the contributors table
I don't want to use an ORM such as SQLAlchemy.
conn = pymysql.connect(
host = 'localhost',
user = 'root',
passwd = 'xxx!',
db = 'xxx'
)
#app.route('/add_contributor',methods = ['POST', 'GET'])
def add_contributor():
name = request.form.get('contrib_name')
question = request.form.get('question')
sql_1 = "INSERT INTO contributors (name) VALUES (%s)"
sql_2 = "SELECT contributor_id from contributors WHERE name=(%s)"
sql_3 = "INSERT INTO questions (contributor_id, question_text) VALUES (%s, %s)"
cursor = conn.cursor()
cursor.execute(sql_1, name)
cursor.fetchall()
conn.commit()
cursor_2 = conn.cursor()
cursor_2.execute(sql_2, name)
contrib_val = cursor_2.fetchall()
contrib_id = contrib_val[0][0]
cursor_3 = conn.cursor()
cursor_3.execute(sql_3, (contrib_id,question))
cursor_3.fetchall()
conn.commit()
I am trying to use one query output into other. but not getting the correct result. Can you please help me how to do this?
Example:
query1 = "select distinct lower(tablename) as tablename from medaff.imedical_metadata where object_type = 'View'"
output of above query is :
tablename
vw_mdcl_insght
vw_fbms_interactions
I want to use above output in other query. Something like this-
query2 = "select * from medaff.imedical_business_metadata where objectname in ('vw_mdcl_insght', 'vw_fbms_interactions')"
How to do this part in python?
I am using below code to run the query:
conn = redshift_conn()
with conn.cursor() as cur:
query1 = "select distinct lower(tablename) as tablename from medaff.imedical_metadata where object_type = 'View'"
cur.execute(sql_query)
result = cur.fetchall()
print(result)
conn.commit()
query2 = "select * from medaff.imedical_business_metadata where objectname in ('vw_mdcl_insght', 'vw_fbms_interactions')"
cur.execute(sql_query)
result = cur.fetchall()
print(result)
conn.commit()
I think you can just use an in query:
select ibm.*
from medaff.imedical_business_metadata ibm
where ibm.objectname in (select lower(im.tablename) as tablename
from medaff.imedical_metadata im
where im.object_type = 'View'
);
It is better to let the database do the work.
I used the below code:
query = "select distinct lower(tablename) from medaff.imedical_metadata where object_type = 'View'"
cur.execute(query)
res = cur.fetchall()
print(res)
res = tuple([item[0] for item in res])
res = str(res)
I am inserting into a table using the following code:
## Connection established ##
sql = """ INSERT INTO Singer ( name ) VALUES( %s ) """
params = ('Rihanna',)
cursor.execute(sql, params)
cursor.fetchall() ## Result - into no result set
cursor.description ## Result - Nonetype
I am not able to understand where am I going wrong?
Thanks
You have to commit your change.
cursor = conn.cursor()
sql = """ INSERT INTO Singer ( name ) VALUES( %s ) """
params = ('Rihanna',)
cursor.execute(sql, params)
conn.commit() # Important, apply changes to database!
cursor.fetchall() ## Result - into no result set
cursor.description ## Result - Nonetype
I have a list that contains the name of columns I want to retrieve from a table in the database.
My question is how to make the cursor select columns specified in the list. Do I have to convert nameList to a string variable before include it in the select statement? Thanks
nameList = ['A','B','C','D',...]
with sqlite3.connect(db_fileName) as conn:
cursor = conn.cursor()
cursor.execute("""
select * from table
""")
As long as you can be sure your input is sanitized -- to avoid SQL injection attack -- you can do:
...
qry = "select {} from table;"
qry.format( ','.join(nameList) )
cursor.execute(qry)
If you're on a really old version of Python do instead:
...
qry = "select %s from table;"
qry % ','.join(nameList)
cursor.execute(qry)
nameList = ["'A(pct)'",'B','C','D',...]
with sqlite3.connect(db_fileName) as conn:
cursor = conn.cursor()
cursor.execute("""
select {} from table
""".format(", ".join(nameList)))