How to create and use database connection ?

FOR MYSQL, USE MODULE pymysql
FOR ORACLE, USE MODULE cx_oracle

import pymysql

# Create connection to MySQL DB
def createConn():
    conn = pymysql.connect(host="10.238.207.56", user="root", passwd="Mypass@123", db="idmgt")
    return conn

# Method to fetch all records
def fetchRecords():
    conn = createConn()
    query = "select * from roles"
    cursor = conn.cursor()
    cursor.execute(query)
    return cursor.fetchall()

# Method to fetch record by ID
def fetchByRoleId(roleId):
    conn = createConn()
    cursor = conn.cursor()
    cursor.execute("""select * from roles where id=%d""" %(roleId))
    return cursor.fetchall()

# First statement : Call upper method to fetch records
rows = fetchRecords()

# Then, Iterate the records
for row in rows:
    for col in row:
        print(col)