ADB-PG上是不是有更方便的函数来计算 同比、环比？

是的，AnalyticDB PostgreSQL版有内置的函数可以方便地计算同比、环比等指标。

例如，ADB-PG 提供了用于环比计算的 LAG和LEAD 函数，用于同比计算的 DATE_TRUNC 函数和DATE_PART 函数。

以下是一些示例查询，演示如何使用这些函数来计算同比和环比：

1. 计算月销售额的环比增长率：

SELECT
  (m1.total_sales - m2.total_sales) / m2.total_sales AS mom_growth_rate
FROM
  (
    SELECT 
      DATE_TRUNC('month', order_date) AS month,
      SUM(order_amount) AS total_sales
    FROM 
      sales_table
    WHERE 
      order_date BETWEEN '2019-01-01' AND '2020-12-31'
    GROUP BY
      1
  ) AS m1
  JOIN 
  (
    SELECT 
      DATE_TRUNC('month', order_date) AS month,
      SUM(order_amount) AS total_sales
    FROM 
      sales_table
    WHERE 
      order_date BETWEEN '2019-01-01' AND '2020-12-31'
    GROUP BY
      1
  ) AS m2
  ON m1.month = m2.month - INTERVAL '1 month';

1. 计算月销售额的同比增长率：

SELECT 
  (m1.total_sales - m2.total_sales) / m2.total_sales AS yoy_growth_rate
FROM 
  (
    SELECT 
      DATE_TRUNC('month', order_date) AS month,
      SUM(order_amount) AS total_sales
    FROM 
      sales_table
    WHERE 
      order_date BETWEEN '2020-01-01' AND '2020-12-31'
    GROUP BY
      1
  ) AS m1
  JOIN 
  (
    SELECT 
      DATE_TRUNC('month', order_date) AS month,
      SUM(order_amount) AS total_sales
    FROM 
      sales_table
    WHERE 
      order_date BETWEEN '2019-01-01' AND '2019-12-31'
    GROUP BY
      1
  ) AS m2
  ON DATE_PART('month', m1.month) = DATE_PART('month', m2.month)

以上仅是示例查询，您可以根据实际的业务需求进行调整和优化。