SQL :如何根据不同列中的值填充自定义表/列

-- 创建一个示例表
CREATE TABLE example (
  id INT,
  name VARCHAR(50),
  category VARCHAR(50),
  value INT
);

-- 向表中插入数据
INSERT INTO example (id, name, category, value)
VALUES
  (1, 'A', 'Category1', 10),
  (2, 'B', 'Category2', 20),
  (3, 'C', 'Category1', 30),
  (4, 'D', 'Category2', 40);

-- 根据不同列中的值填充自定义表/列
SELECT
  id,
  name,
  CASE
    WHEN category = 'Category1' THEN 'CustomValue1'
    WHEN category = 'Category2' THEN 'CustomValue2'
    ELSE 'CustomValue3'
  END AS custom_column
FROM example;