Develop Reference

Validation of inputs in database using python in mariadb-connector

I want to know how to validate inputs using MariaDB Connector/Python. It just like a signup page that won't allow to use same username.
PSEUDOCODE GO LIKE THIS
CHECKIF DATA IN DATABASE
IF USER_INPUT == DATA IN DATABASE
PRINT("DATA ALREADY EXIST!")
ELSEIF
INSERT DATA IN DATABASE
PRINT("DATA ADDED")
I hope you get what am I trying to do. Thank you in advance for your response.
I tried doing it in this way
conn = mariadb.connect(host="127.0.0.1",
user="root",
database="blankshot",
passwd="")
#Get Cursor
cur = conn.cursor()
query = "INSERT INTO testtable(test) VALUES('"+strloc+"')"
CheckQuery = "SELECT test FROM testtable where test='"+strloc+"'"
cur.execute(CheckQuery)
cur.fetchone()
if location == '':
print("Don't leave it blank")
elif len(strloc) != 0:
if(cur.next()):
print("Data already exist")
else:
cur.execute(query)
inf = cur.lastrowid
cur.close()
except mariadb.Error as e:
print(f"Error connecting to MariaDb platform:{e}")
conn.commit()
print(f"Last Inserted ID: ", str(inf))
conn.close()
Doing this was nothing happened. It still records the same inputs

What should I put for the first parameter when calling "get_Tables_byName" function?

I'm writing a python code to read from mysql database:
def create_server_connection(host, user, password):
connection = None
try:
connection = pymysql.connect(host='localhost',
user='root',
password='pwd',
database='raw_data',
cursorclass=pymysql.cursors.DictCursor)
print("MySQL Database connection successful")
except err as error:
print(f"Error: '{error}'")
return connection
def read_query(connection, query):
cur = connection.cursor()
result = None
try:
cur.execute(query)
result = cur.fetchall()
return result
except err as error:
print(f"Error: '{error}'")
return cur
def get_Tables_byName(cursor, tableName):
q1 = f'''
SELECT table_name FROM raw_data.tables
where table_name like '{tableName}'; '''
res = []
cursor.execute(q1)
for row in cursor:
res.append(row[0])
return res
get_Tables_byName(cursor,'data_31942010201')
If I want to call get_Tables_byName function, what should I put in the first parameter? If I put cursor, the error message shows NameError: name 'cursor' is not defined

python psycopg2 can't load the table in the database

I successfully access the database, however, I can't load the table inside the database. I am quite sure that the name of the table is correct, the database is a mimic iii database. Please give me a helping hand, thanks a lot!
import psycopg2
try:
connection = psycopg2.connect(user="postgres",
password="xxxxxxx",
host="localhost",
port="5432",
database="mimic")
cursor = connection.cursor()
postgreSQL_select_Query = "select * from admissions"
cursor.execute(postgreSQL_select_Query)
print("Selecting rows from mobile table using cursor.fetchall")
admissions_records = cursor.fetchall()
print("Print each row and it's columns values")
for row in admissions_records:
print("x = ", row[0], )
print("y = ", row[1])
print("z = ", row[2], "\n")
except (Exception, psycopg2.Error) as error:
print("Error while fetching data from PostgreSQL", error)
finally:
# closing database connection.
if connection:
cursor.close()
connection.close()
print("PostgreSQL connection is closed")
Here's the output:
Error while fetching data from PostgreSQL relation "admissions" does not exist
LINE 1: select * from admissions
^
PostgreSQL connection is closed

I don't know why curs.execute not working

i'm studying about mysql connection with python(pycharm)
i have question about curs.execute()
when it work and when it not work...
in my code i write remarks about not working point
import pymysql
try:
conn = pymysql.connect(host='localhost', user='root', password='1234', db='university')
conn.set_charset('utf8')
curs = conn.cursor(pymysql.cursors.DictCursor) #Dictionary cursor 생성
# curs = conn.cursor()
print("Connected to MySQL")
sql = "SELECT sno, midterm, final from db_score where midterm >= 20 and final >= 20 order by sno"
# sql = "select* from db_score"
curs.execute(sql)
#this point not work :(
except Exception as e:
print(str(e))
finally:
if conn:
curs.close()
conn.close()
print("MySql connection is closed")
and fetchall() didnt work :(\
import pandas as pd
import pymysql
xl_file = 'db_score.xlsx'
df = pd.read_excel(xl_file)
tp = list(df.itertuples(index=False, name=None))
# ('sno', 'attendance', 'homework', 'discussion', 'midterm', 'final', 'score', 'grade')
try:
conn = pymysql.connect(host='localhost', user='root', password='1234', db='university')
conn.set_charset('utf8')
#curs = conn.cursor(pymysql.cursors.DictCursor)
curs = conn.cursor()
print("Connected to MySQL")
sql = "INSERT INTO db_score VALUES (%s, %s, %s, %s, %s, %s, %s, %s)"
for i in range(0, len(df.index)):
# print('hi')
curs.execute(sql, tp[i])
#why work i dont know because other part is not working
# sql2 = "SELECT* from db_score"
# curs.execute(sql2)
# try execute, but not work
records = curs.fetchall()
for row in records:
print("why didn't work")
print(row)
#print not work :(
conn.commit()
except Exception as e:
print(str(e))
conn.rollback()
finally:
if conn:
curs.close()
conn.close()
print("MySql connection is closed")
please comment why work and why not work please...
thanks for watching
db connection is so hard:(

How to add exception to python function?

Good day. I wrote an application on python that collects call logs from the Avaya PBX and writes them to the mysql database. It works well, but sometimes the PBX sends an empty string for some reason and the program fails. I attach the screen and code below. I understand that you need to wrap the function in an exception: try except, but I don’t understand how to do it. Please tell me how to do this.enter image description here
def write_db(item, *agrs):
connection = pymysql.connect(host='localhost',
user='acdr',
password='it8ejokd',
db='avaya_cdr',
charset='utf8mb4',
cursorclass=pymysql.cursors.DictCursor)
DBTBL = "cdr102019"
DBFLD = "Date_call, Time_call, `Sec_dur`, `clg_num_in_tag`, `dialed_num`, dep_called, dep_dialed"
dep_num_call = find_dep(item[3].replace(' ', ''))
name_dep_call = name_dep(dep_num_call)
dep_num_dial = find_dep(item[4].replace(' ', ''))
name_dep_dial = name_dep(dep_num_dial)
item.append(name_dep_call)
item.append(name_dep_dial)
item[1] = item[1] + "00"
try:
with connection.cursor() as cursor:
sql = "INSERT INTO "+DBTBL+" ("+DBFLD+") VALUES (%s,%s,%s,%s,%s,%s,%s)"
cursor.execute(sql, (item))
connection.commit()
finally:
connection.close()
# Задаем адрес сервера
SERVER_ADDRESS = ('', 5100)
# Настраиваем сокет
server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.bind(SERVER_ADDRESS)
server_socket.listen(5)
print('server is running, please, press ctrl+c to stop')
# Слушаем запросы и пишем в db
while True:
connection, address = server_socket.accept()
data = connection.recv(1024)
if not(b'\x00\x00\x00' in data) and not(b'1370' in data):
str = data.decode("utf-8")
item=[str[0:6],str[7:11],str[12:17],str[18:33],str[34:57]]
print(item)
write_db(item)
connection.close()

You'll have to catch the exception, so we can cater for a few types, but just to be sure and get you up and running, you could do the following :)
try:
with connection.cursor() as cursor:
sql = (
"INSERT INTO "+DBTBL+" ("+DBFLD+") VALUES "
"(%s,%s,%s,%s,%s,%s,%s)"
)
cursor.execute(
sql,
(item),
)
connection.commit()
except Exception as e:
print("Error occurred: %s"% e)
finally:
connection.close()

This should do the trick. I've used all four elements of try/except/else/finally here, with brief explanations of when they're executed.
try:
with connection.cursor() as cursor:
sql = "INSERT INTO "+DBTBL+" ("+DBFLD+") VALUES (%s,%s,%s,%s,%s,%s,%s)"
cursor.execute(sql, (item))
except Exception: # If this code fails, ignore it
pass
else: # If the code inside 'try' succeeds, execute this code.
connection.commit()
finally: # Regardless of whether or not the code inside 'try' succeeds, execute this code
connection.close()