Create a simple database class in Python that supports add, delete, update, and query operations

Document 对象参考手册Python3 Examples

We will create a simple database classSimpleDB, which uses Python dictionaries to simulate database tables. This class will support basic add, delete, update, and query operations.

Example

class SimpleDB:
    def __init__(self):
        self.db = {}

    def insert(self, key, value):
        self.db[key] = value
        print(f"Inserted: {key} -> {value}")

    def delete(self, key):
        if key in self.db:
            del self.db[key]
            print(f"Deleted: {key}")
        else:
            print(f"Key {key} not found.")

    def update(self, key, value):
        if key in self.db:
            self.db[key] = value
            print(f"Updated: {key} -> {value}")
        else:
            print(f"Key {key} not found.")

    def select(self, key):
        if key in self.db:
            print(f"Selected: {key} -> {self.db[key]}")
        else:
            print(f"Key {key} not found.")

    def show_all(self):
        print("Database Contents:")
        for key, value in self.db.items():
            print(f"{key} -> {value}")

# Example usage
db = SimpleDB()
db.insert('name', 'Alice')
db.insert('age', 30)
db.show_all()
db.update('age', 31)
db.select('name')
db.delete('age')
db.show_all()

Code analysis:

  1. __init__The method initializes an empty dictionarydbto store data.
  2. insertThe method is used to add new key-value pairs to the database.
  3. deleteThe method is used to delete the key-value pair of the specified key.
  4. updateThe method is used to update the value of the specified key.
  5. selectThe method is used to query the value of the specified key.
  6. show_allThe method is used to display all key-value pairs in the database.

Output result:

Inserted: name -> Alice
Inserted: age -> 30
Database Contents:
name -> Alice
age -> 30
Updated: age -> 31
Selected: name -> Alice
Deleted: age
Database Contents:
name -> Alice

Document 对象参考手册Python3 Examples

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