用PostgreSQL 绘制一颗圣诞树

看到用 GaussDB T 绘制一颗圣诞树，又有Oracle绘制圣诞树，现写一个PostgreSQL的：

WITH leafs AS
 (SELECT lpad(rpad('*', ((row_number() over()) ::INT - 1) * 2 + 1 +
                    (t1.lv - 1) * 2, '*'), (row_number() over())
               ::INT + 20 + t1.lv) leaf
    FROM generate_series(1, 3) AS t2(lv),
         generate_series(1, 5) AS t1(lv)),
root AS
 (SELECT lpad(rpad('*', 5, '*'), 24) FROM generate_series(1, 4))
SELECT leaf
  FROM leafs
UNION ALL
SELECT * FROM root;

复制

                  *
                *****
              *********
            *************
          *****************
             ***********
           ***************
         *******************
       ***********************
     ***************************
        *********************
      *************************
    *****************************
  *********************************
*************************************
                *****
                *****
                *****
                *****
复制

相比于GaussDB和Oracle，PostgreSQL代码更加紧凑简单。