4 курс 1 семестр / Лабораторные / Python / LR8_2

import psycopg2
import matplotlib.pyplot as plt
import numpy as np

conn = psycopg2.connect(
host="127.0.0.1",
database="students",
user="postgres",
password="123",
port="5432"
)

cur = conn.cursor()

cur.execute("""
WITH cte AS (
SELECT employees.job_id, job_title, salary
FROM employees
JOIN jobs ON employees.job_id = jobs.job_id
)
SELECT
CASE
WHEN job_title LIKE '%Manager%' THEN 'Manager'
WHEN job_title LIKE '%Clerk%' THEN 'Clerk'
WHEN job_title LIKE '%President%' THEN 'President'
ELSE 'Other'
END AS job_group,
MAX(salary) AS max_salary
FROM cte
GROUP BY job_group
ORDER BY max_salary DESC
""")

records = cur.fetchall()

job_groups = []
max_salaries = []
for record in records:
job_group = record[0]
max_salary = record[1]
job_groups.append(job_group)
max_salaries.append(max_salary)

x = np.arange(len(job_groups))

fig, ax = plt.subplots()
ax.bar(x, max_salaries)
ax.set_xticks(x)
ax.set_xticklabels(job_groups)
ax.set_ylabel("Максимальная зарплата")
ax.set_xlabel("Группа по должностям")
plt.title("Максимальная зарплата сотрудников по каждой группе")

plt.show()

conn.close()