I have a list
A=[1,2,3,3,4,5,6,8,90,8,6,5]
I want to put this list into a postgres table
After making a cursor and connection
I tried this
for i in A:
cusror.execute("Insert into schema1.table1 Values (%s)" ,i)
connection.commit()
But getting an error
TypeError: Not all arguments converted during string formatting.
Can someone help me out please
Use this function I will provide, just make sure to change TABLE_NAME and the columns for the ones you will be inserting:
import psycopg2
def bulkInsert(records):
try:
connection = psycopg2.connect(user="sysadmin",
password="pynative##29",
host="127.0.0.1",
port="5432",
database="postgres_db")
cursor = connection.cursor()
# Here replace the table and the columns
sql_insert_query = """ INSERT INTO TABLE_NAME (id, model, price)
VALUES (%s,%s,%s) """
# executemany() to insert multiple rows
result = cursor.executemany(sql_insert_query, records)
connection.commit()
print(cursor.rowcount, "Record inserted successfully into mobile table")
except (Exception, psycopg2.Error) as error:
print("Failed inserting record into mobile table {}".format(error))
finally:
# closing database connection.
if connection:
cursor.close()
connection.close()
print("PostgreSQL connection is closed")
# Example of how to use the function
records_to_insert = [(4, 'LG', 800), (5, 'One Plus 6', 950)]
bulkInsert(records_to_insert)
The 2nd argument to cursor.execute() should be a tuple. Try:
for i in A:
cursor.execute("Insert into schema1.table1 Values (%s)", (i,))
connection.commit()
Noting down a point from documentation -
For positional variables binding, the second argument must always be a sequence, even if it contains a single variable (remember that Python requires a comma to create a single element tuple):
>>> cur.execute("INSERT INTO foo VALUES (%s)", "bar") # WRONG
>>> cur.execute("INSERT INTO foo VALUES (%s)", ("bar")) # WRONG
>>> cur.execute("INSERT INTO foo VALUES (%s)", ("bar",)) # correct
>>> cur.execute("INSERT INTO foo VALUES (%s)", ["bar"]) # correct
Correct answer for your issue would be
for i in A:
cusror.execute("Insert into schema1.table1 Values (%s)" ,(i,))
connection.commit()
Using psycopg2 Fast execution helpers:
import psycopg2
from psycopg2.extras import execute_batch,execute_values
con = psycopg2.connect("dbname=test user=postgres host=localhost port=5432")
cur = con.cursor
A=[1,2,3,3,4,5,6,8,90,8,6,5]
param_list = [[id] for id in A]
#Using execute_batch
sql = "Insert into public.table1 values (%s)"
execute_batch(cur, sql, param_list)
con.commit()
#Using execute_values
sql = "Insert into public.table1 values %s"
execute_values(cur, sql, param_list)
con.commit()
in my python code I insert a value into a table.
In the table, there is a sequence which automatically assigns an ID.
After the insert, I want to get this it back in to my python application:
import cx_Oracle, sys
with cx_Oracle.connect(user=ORA_USER,password=ORA_PWD,dsn=ORA_DSN) as conn:
with conn.cursor() as cur:
cur.execute("Insert into my_table columns(data) values ('Hello')")
conn.commit()
with cx_Oracle.connect(user=ORA_USER,password=ORA_PWD,dsn=ORA_DSN) as conn:
with conn.cursor() as cur:
r = cur.execute("select id from my_table where data = 'Hello'")
print(r)
if r is None:
print("Cannot retrieve ID")
sys.exit()
Unfortunately, the result set r is always "None" even though the value has been inserted properly (checked via sqldeveloper).
What am I doing wrong?
I even open a new connection to be sure to grab the value...
After calling execute() for a SELECT statement you need to call fetchone(), fetchmany() or fetchall() as shown in the cx_Oracle documentation SQL Queries.
Or you can use an iterator:
with connection.cursor() as cursor:
try:
sql = """select systimestamp from dual"""
for r in cursor.execute(sql):
print(r)
sql = """select 123 from dual"""
(c_id,) = cursor.execute(sql).fetchone()
print(c_id)
except oracledb.Error as e:
error, = e.args
print(sql)
print('*'.rjust(error.offset+1, ' '))
print(error.message)
However to get an automatically generated ID returned without the overhead of an additional SELECT, you can change the INSERT statement to use a RETURNING INTO clause. There is an example in the cx_Oracle documentation DML RETURNING Bind Variables that shows an UPDATE. You can use similar syntax with INSERT.
With the table:
CREATE TABLE mytable
(myid NUMBER(11) GENERATED BY DEFAULT ON NULL AS IDENTITY (START WITH 1),
mydata VARCHAR2(20));
You can insert and get the generated key like:
myidvar = cursor.var(int)
sql = "INSERT INTO mytable (mydata) VALUES ('abc') RETURNING myid INTO :bv"
cursor.execute(sql, bv=myidvar)
i, = myidvar.getvalue()
print(i)
If you just want a unique identifier you get the ROWID of an inserted row without needing a bind variable. Simple access cursor.lastrowid after executing an INSERT.
I want to insert a new row in my table by using the python-mariadb connector. For that I prefer to use the SET clause.
For some reason it does work if I only want to save ints (i.e y=2), but when I use a string, the following error occurs
Unknown column 'myString' in 'field list'
It seems it thinks the content of the string is a column name? Any idea how to fix that (I can do it with INSERT INTO ... VALUES ..., but I want to use the SET clause here). From my understanding, it should save both an int and a str without throwing an error
Thank you.
See the code example below
def myfunction():
x = 1
y ='myString'
db = connect_db()
cur = db.cursor()
sql = "INSERT INTO Table SET col1={}, col2={}"
cur.execute(sql.format(x, y))
db.commit()
db.close()
return
Here the MariaDB Connector, but this should be fine as it works for other db functions.
import mariadb
def connect_db():
db = mariadb.connect(
user="user",
password="123",
host="localhost",
port=3306,
database="DB"
)
db.autocommit = False
return db
you are not using right syntax for insert
sql = "INSERT INTO Table (col1,col2) values({}, {})"
but if you want to update an existing row:
sql = "UPDATE Table SET col1={}, col2={} WHERE id = {}"
and probably you need a where clause
The code in question produces the SQL statement:
INSERT INTO Table SET col1=1, col2=myString;
This is incorrect syntax, and strings must be in single-quotes:
INSERT INTO Table (col1, col2) VALUES (1, 'myString');
def myfunction():
x = 1
y ='myString'
db = connect_db()
cur = db.cursor()
sql = "INSERT INTO Table (col1, COL2) VALUES ({}, '{}')"
cur.execute(sql.format(x, y))
db.commit()
db.close()
return
But the above is fragile. Don't use string building methods to create SQL statements, it is much better to use parameter binding.
def myfunction():
x = 1
y ='myString'
db = connect_db()
cur = db.cursor()
sql = "INSERT INTO Table (col1, col2) VALUES (?, ?)"
cur.execute(sql, (x, y))
db.commit()
db.close()
return
The MariaDB connector documentation explains these things.
Retrieving Data
Once you have the initial code in place you can start working with the data. The first thing you should do is try to
retrieve information from the database. Here is code for a query
against the employees database:
cur.execute(
"SELECT first_name,last_name FROM employees WHERE first_name=?",
(some_name,))
MariaDB Connector/Python uses prepared statements, sanitizing and inserting the values from the tuple into the position
of the question marks (?). This is safer than inserting through
f-strings or format specifiers when working with user provided
information.
The query results are stored in a list in the cursor object. To view
the results, you can loop over the cursor.
Adding Data
Using the same execute() method with an INSERT statement, you can add rows to the table.
cursor.execute(
"INSERT INTO employees (first_name,last_name) VALUES (?, ?)",
(first_name, last_name))
I'm trying to fill in a SQLite database using the Python library sqlite3. In this example, the idea is simply to read data from a file and populate the database, however, although it seems the table is being created, the database is not growing and values are not written to it.
The code I have is below:
import sqlite3
def update_db(c, key, val):
sql = ''' UPDATE atable SET f1 = ? WHERE id = ?; '''
c.execute(sql, (val, key))
def create_table(c):
sql = ''' CREATE TABLE atable (id text PRIMARY KEY, f1 integer DEFAULT 0); '''
c.execute(sql)
with sqlite3.connect('test.db') as conn:
c = conn.cursor()
create_table(c)
with open('file1.txt') as f1:
for line in f1:
l = line.strip().split()
update_db(c, l[0], int(l[1]))
conn.commit()
This code runs without errors, but when trying to query this database, either with Python:
with sqlite3.connect('test.db') as conn:
c = conn.cursor()
c.execute('SELECT * FROM atable;')
for row in c:
print(row)
or in the SQLite command interface:
$ sqlite3 test.db
SQLite version 3.8.10.2 2015-05-20 18:17:19
Enter ".help" for usage hints.
sqlite> SELECT * FROM atable;
sqlite> .tables
atable
sqlite>
the output is always empty (but it looks the table was correctly create). What am I doing wrong here?
The 'file1.txt' for testing is this:
foo 2
bar 0
baz 1
The SQL syntax for adding rows to your table is:
INSERT INTO atable (id, f1) VALUES (?, ?);
UPDATE will do nothing if there are not already rows in the table.
If you want to insert or replace an existing row, sqlite also supports an INSERT OR REPLACE command.
I am trying to insert info from a pandas DataFrame into a database table by using a function that I wrote:
def insert(table_name="", name="", genere="", year=1, impd_rating=float(1)):
conn = psycopg2.connect("dbname='database1' user='postgres' password='postgres333' host='localhost' port=5433 ")
cur = conn.cursor()
cur.execute("INSERT INTO %s VALUES %s,%s,%s,%s" % (table_name, name, genere, year, impd_rating))
conn.commit()
conn.close()
When I try to use this function like this:
b=0
for row in DF['id']:
insert(impd_rating=float(DF['idbm_rating'][b]),
year=int(DF['year'][b]),
name=str(DF['name'][b]),
genere=str(DF['genere'][b]),
table_name='test_movies')
b = b+1
I get the following syntax error:
SyntaxError: invalid syntax
PS D:\tito\scripts\database training> python .\postgres_script.py
Traceback (most recent call last):
File ".\postgres_script.py", line 56, in <module>insert (impd_rating=float(DF['idbm_rating'][b]),year=int(DF['year'][b]),name=str(DF['name'][b]),genere=str(DF['genere'][b]),table_name='test_movies')
File ".\postgres_script.py", line 15, in insert
cur.execute("INSERT INTO %s VALUES %s,%s,%s,%s" % (table_name ,name ,genere , year,impd_rating))
psycopg2.ProgrammingError: syntax error at or near "Avatar"
LINE 1: INSERT INTO test_movies VALUES Avatar,action,2009,7.9
I also tried to change the str replacement method from %s to .format()
but I had the same error.
The error message is explicit, this SQL command is wrong at Avatar: INSERT INTO test_movies VALUES Avatar,action,2009,7.9. Simply because values must be enclosed in parenthesis, and character strings must be quoted, so the correct SQL is:
INSERT INTO test_movies VALUES ('Avatar','action',2009,7.9)
But building a full SQL command by concatenating parameters is bad practice (*), only the table name should be directly inserted into the command because is is not a SQL parameter. The correct way is to use a parameterized query:
cur.execute("INSERT INTO %s VALUES (?,?,?,?)" % (table_name,) ,(name ,genere , year,impd_rating)))
(*) It was the cause of numerous SQL injection flaws because if one of the parameter contains a semicolumn (;) what comes after could be interpreted as a new command
Pandas has a DataFrame method for this, to_sql:
# Only needs to be executed once.
conn=psycopg2.connect("dbname='database1' user='postgres' password='postgres333' host='localhost' port=5433 ")
df.to_sql('test_movies', con=conn, if_exists='append', index=False)
This should hopefully get you going in the right direction.
In your original query
INSERT INTO %s VALUES %s,%s,%s,%s
there is a sql problem: you need braces around the values, i.e. it should be VALUES (%s, %s, %s, %s). On top of that the table name cannot be merged as a parameter, or it would be escaped as a string, which is not what you want.
You can use the psycopg 2.7 sql module to merge the table name to the query, with placeholders for the values:
from psycopg2 import sql
query = sql.SQL("INSERT INTO {} VALUES (%s, %s, %s, %s)").format(
sql.Identifier('test_movies'))
cur.execute(query, ('Avatar','action',2009,7.9))
This will make secure both merging the table name and the arguments to the query.
Hello mohamed mahrous,
First install psycopg2 package for the access access PostgreSQL database.
Try this below code,
import psycopg2
conn=psycopg2.connect("dbname='database1' user='postgres' password='postgres333' host='localhost' port=5433 ")
cur=conn.cursor()
def insert(table_name,name,genere,year,impd_rating):
query = "INSERT INTO "+table_name+"(name,genere,year,impd_rating) VALUES(%s,%s,%s,%s)"
try:
print query
cur.execute(query,(name,genere,year,impd_rating))
except Exception, e:
print "Not execute..."
conn.commit()
b=0
for row in DF['id']:
insert (impd_rating=float(DF['idbm_rating'][b]),year=int(DF['year'][b]),name=str(DF['name'][b]),genere=str(DF['genere'][b]),table_name='test_movies')
b= b+1
conn.close()
Example,
import psycopg2
conn=psycopg2.connect("dbname='database1' user='postgres' password='postgres333' host='localhost' port=5433 ")
cur=conn.cursor()
def insert(table_name,name,genere,year,impd_rating):
query = "INSERT INTO "+table_name+"(name,genere,year,impd_rating) VALUES(%s,%s,%s,%s)"
try:
print query
cur.execute(query,(name,genere,year,impd_rating))
except Exception, e:
print "Not execute"
conn.commit()
b=0
for row in DF['id']:
insert (impd_rating="7.0",year="2017",name="Er Ceo Vora Mayur",genere="etc",table_name="test_movies")
b= b+1
conn.close()
I hope my answer is helpful.
If any query so comment please.
i found a solution for my issue by using sqlalchemy and pandas to_sql method
thanks for help everyone
from sqlalchemy import *
import pandas as pd
def connect(user, password, db, host='localhost', port=5433):
'''Returns a connection and a metadata object'''
# We connect with the help of the PostgreSQL URL
# postgresql://federer:grandestslam#localhost:5432/tennis
url = 'postgresql://{}:{}#{}:{}/{}'
url = url.format(user, password, host, port, db)
# The return value of create_engine() is our connection object
con = sqlalchemy.create_engine(url, client_encoding='utf8')
# We then bind the connection to MetaData()
meta = sqlalchemy.MetaData(bind=con, reflect=True)
return con, meta
con, meta = connect('postgres','postgres333','database1')
movies= Table('test',meta,
Column('id',Integer,primary_key=True),
Column('name',String),
Column('genere',String),
Column('year',Integer),
Column('idbm_rating',REAL))
meta.create_all(con)
DF=pd.read_csv('new_movies.txt',sep=' ',engine='python')
DF.columns=('id','name' ,'genere' ,'year' ,'idbm_rating' )
DF.to_sql('movies', con=con, if_exists='append', index=False)