如何在python中使用Join只显示部门ID的部门名称？

Question

通过使用员工数据库在python中导入psycopg2。我正在尝试插入新的员工详细信息，并在员工表中显示有关员工的所有详细信息（部门编号除外），它应该显示部门名称。我不知道，任何想法都会有所帮助。 enter image description here

这是我的PostgreSQL员工和部门表

这是我的python代码：

import datetime

import psycopg2

conn = psycopg2.connect(database="emp", user="postgres",
                    password="12345", host="127.0.0.1", port="5432")

cur = conn.cursor()

emp_name = str(input("Enter new employee name: "))
while True:
    gender = str(input("Type your gender: "))
    if gender == 'M' or gender == 'F':
        break
hire_date = input("Enter hire date(YYYY-MM-DD): ")
year, month, day = map(int, hire_date.split('-'))
hiredate = datetime.date(year, month, day)
deptid = str(int(input("Enter department ID: ")))
salary = str(int(input("Enter your salary: ")))
cur.execute("INSERT INTO employee(emp_name, gender, hire_date, 
             deptid, salary) VALUES (%s, %s, %s, %s, %s)", 
            (emp_name, gender, hire_date, deptid, salary))
cur.execute("SELECT * FROM employee")
rows = cur.fetchall()
print('\n'.join(str(row) for row in rows))
print("Created successfully!")

conn.commit()

conn.close()

Answer 1

您可以通过传递deptid仅选择部门名称，也可以使用psycopg2.extras

cursor.execute('''SELECT deptname 
      from department where deptid = %(department_id)d''', {'department_id': deptid})

或者如果您想通过传递员工ID来加入

cursor.execute('''SELECT deptname 
      from department d join 
       employee e 
 on d.deptd = e.deptid where empno = %(employee_id)d''',
{'employee_id': empid} ) #empid from user input


import psycopg2.extras
cur = conn.cursor(cursor_factory=psycopg2.extras.DictCursor)
cur.execute("""SELECT * from department""")
rows = cur.fetchall()
for row in rows:
   print (" Department name :  ", row['deptname']) #display department name

编辑

  

但是我想显示具有部门名称的员工的所有详细信息   而不是绝妙的

使用这样的查询

SELECT e.emp_no,e.emp_name,e.gender, --other columns except deptid
       d.deptname
             from department d join 
           employee e 
     on d.deptd = e.deptid where e.empno = ?  pass the required empno