I'm noob at python, and I'm trying to do some operations in some tables.
At the moment I'm doing this with hard coding the tables:
cur.execute("select id,email from table1;")
but I'm want to change the tables to and variable to construct a function, like:
cur.execute("select id,email from table;")
How I can do this?
Many thanks
I'm using python3 with psycopg2
#open connection with db
conn = psycopg2.connect(host="localhost",database="test", user="test", password="test")
cur = conn.cursor()
#Select id
cur.execute("select id,email from customers;")
#put ids on list
row = cur.fetchone()
Also I tried this:
sql = "select id,email from %s"
val = customers
cur.execute(sql, val)
And I have this error:
File "updateemails.py", line 14, in <module>
val = (customers)
NameError: name 'customers' is not defined```
Related
Python 3.8.10
streamlit==1.9.0
pandas==1.4.2
psycopg2-binary==2.9.3
Loading a Postgres table directly into a Pandas DataFrame with the following code.
df = pd.DataFrame(run_query("SELECT * FROM schema.tablename;"))
Displaying it with either streamlit.dataframe(df) or streamlit.write(df) loses the column names.
In order to capture the column names, I use this kluge.
# Initialize connection.
#st.experimental_singleton
def init_connection():
return psycopg2.connect(**st.secrets["postgresservername"])
conn = init_connection()
# Perform query.
#st.experimental_memo(ttl=600)
def run_query(query):
with conn.cursor() as cur:
cur.execute(query)
return cur.fetchall()
def load_table_as_dataframe(table):
# This is super klugy.
data = run_query("SELECT * FROM schema.{};".format(str(table)))
columns = run_query("SELECT *FROM information_schema.columns WHERE table_schema = 'schema' AND table_name = '{}';".format(str(table)))
# Fish out the actual column names
columns = [c[3] for c in columns]
df = pd. DataFrame(data, columns = columns)
return df
df = load_table_as_dataframe("tablename")
Which works...
Is there a better way to collect the needed data (and columns names) into a Pandas DataFrame within Postgres and Streamlit?
Using...
df = pd.read_sql("SELECT * FROM schema.{};".format(str(table)), conn)
...solved the issue. (Thx #parfait)
I'm pretty new to python or programming at all so I'd like to get help on the following problem
My table is set up like this:
https://i.imgur.com/KFPq2DI.png
Now I try to count all '✓' and set the number to column Teilnahme.
teilnahmencounter(ctx):
i=0
# Connect
connection = sqlite3.connect("kekse.db")
# cursor
cursor = connection.cursor()
# Abfrage
sql = "SELECT * FROM kekse ORDER BY ID"
cursor.execute(sql)
connection.commit()
for dsatz in cursor:
i = 0
for x in range(2 , 19):
if str(dsatz[x]) == '✓':
i += 1
cursor.execute('UPDATE kekse SET Teilnahme='+str(i)+' WHERE ID=?', dsatz[0]
)
connection.commit()
#print(dsatz[1], i, "Teilnahmen")
connection.close()
Try and use cast in your update where its getting updated -
import sqlite3
# Connect
con = sqlite3.connect("dbname.db")
# cursor
cur = con.cursor()
for row in cur.execute("select * from testtab"):
print(row)
cur.execute("update testtab set id=21 where id = cast("+str(2)+" as int)")
con.commit()
con.close()
I am trying to write a python function that updates a postgres database. The table to be updated is given (department)
Below is the function I wrote:
def modify_dept_budget(deptName, newBudget):
connection = None
try:
connection = connector() # This is a function I wrote to connect so I can hide my credentials.
cursor1 = connection.cursor()
query1 = f"select dept_name from department"
cursor1.execute(query1)
results1 = cursor1.fetchall()
results1 = [result[0] for result in results1]
if deptName in results1:
idx = results1.index(deptName)
print(results1[idx])
cursor2 = connection.cursor()
query = f"UPDATE department SET budget = %s WHERE dept_name == {deptName}"
cursor2.execute(query, [newBudget])
cursor3 = connection.cursor()
cursor3.execute(f'SELECT * FROM department')
results2 = cursor3.fetchall()
headers = [item[0] for item in cursor3.description]
df = pd.DataFrame(data = results2, columns = headers)
print(df)
except(Exception, psycopg2.DatabaseError) as error:
print(error)
finally:
if connection:
cursor1.close()
cursor2.close()
cursor3.close()
connection.close()
When I run modify_dept_budget('Music', 85000), I get the following error:
Music
column "music" does not exist
LINE 1: ...PDATE department SET budget = 85000 WHERE dept_name == Music
^
---------------------------------------------------------------------------
UnboundLocalError Traceback (most recent call last)
<ipython-input-77-16e7278e3358> in <module>
----> 1 modify_dept_budget('Music', 85000)
<ipython-input-76-80361b6ddf35> in modify_dept_budget(deptName, newBudget)
26 cursor1.close()
27 cursor2.close()
---> 28 cursor3.close()
29 connection.close()
UnboundLocalError: local variable 'cursor3' referenced before assignment
Can anyone help me figure out what is going on?
You have two problems. First, SQL does not use the double == for the equality test. Just plain =. Second, that string literal needs to be quoted. Unless you need a table name or a field name, you won't be using f-strings with SQL. So, do:
query = "UPDATE department SET budget = %s WHERE dept_name = %s"
cursor2.execute(query, [newBudget, deptName])
I am trying to insert and extract data using a sqlite database, but I keep running into this error:
Traceback (most recent call last):
File "Database_Section\Dsite.py", line 14, in <module>
insert("Cup", 4, 5)
File "Database_Section\Dsite.py", line 10, in insert
cur.execute(cur.execute("INSERT INTO store(item, quantity, price) VALUES ('?,?,?')", ('item','quantity','price')))
sqlite3.OperationalError: 1 values for 3 columns`enter code here
And this is my code:
import sqlite3
conn = sqlite3.connect('lite.db')
cur = conn.cursor()
cur.execute('CREATE TABLE IF NOT EXISTS store(item TEXT, quantity INTEGER, price REAL)')
conn.commit()
def insert(item,quantity,price):
conn = sqlite3.connect('lite.db')
cur = conn.cursor()
cur.execute(cur.execute("INSERT INTO store(item, quantity, price) VALUES ('?,?,?')", ('item','quantity','price')))
conn.commit()
conn.close()
impo
insert("Cup", 4, 5)
def view():
conn = sqlite3.connect('lite.db')
cur = conn.cursor()
cur.execute("SELECT * FROM store")
rows = cur.fetchall()
conn.close()
return rows
print(view())
"INSERT INTO store(item, quantity, price) VALUES ('?,?,?')"
This tries to insert the literal string '?,?,?' to the table, and fails because it's a single value and there are 3 columns (as the errors says).
You should remove the quotes surrounding the placeholders:
"INSERT INTO store(item, quantity, price) VALUES (?,?,?)"
New to using sqlite with python. I am trying to insert two date values into two date columns in sqlite db via Python.
import sqlite3
def create_connection(db_file):
# Create a database connection to a SQLite database
# Param: db_file as str. Return: connection objects or None
try:
conn = sqlite3.connect(db_file)
cur = conn.cursor()
return conn, cur
except Error as e:
print (e)
return None
my_conn, my_cur = create_connection(dpd_sqlite_db_dir)
def create_sqlite_table_if_nonexist(conn, table_name):
sql = 'create table if not exists '+table_name+' (data_download_date datetime, script_executed_date datetime)'
conn.execute(sql)
create_sqlite_table_if_nonexist(my_conn, 'df_timestamp_en')
def insert_timestamp(conn, timestamp):
# execute insert into db
sql = ''' INSERT INTO df_timestamp_en (data_download_date, script_executed_date) VALUES(?,?) '''
cur = conn.cursor()
cur.execute(sql, timestamp)
return cur
timestamp_info = ('2018-10-30', '2018-11-30')
insert_timestamp(my_conn, timestamp_info)
It runs and created the table with two date columns, but it doesn't insert the timestamp_info's values.