当DropDownList为NULL时返回所有数据

from flask import Flask, request, jsonify

app = Flask(__name__)

@app.route('/data', methods=['GET'])
def get_data():
    dropdown_value = request.args.get('dropdown_value')
    
    if dropdown_value is None:
        # 返回所有数据
        data = [
            {'id': 1, 'name': 'Data 1'},
            {'id': 2, 'name': 'Data 2'},
            {'id': 3, 'name': 'Data 3'},
            # ...
        ]
    else:
        # 根据下拉列表的值返回相应的数据
        # ...
        pass
    
    return jsonify(data)

if __name__ == '__main__':
    app.run()

SELECT * FROM table_name
WHERE dropdown_value IS NULL OR column_name = dropdown_value;