如何从string_agg重新排列值

Question

  

如何重新排列或简化string_agg中的值？

     

例如，从该值1 | 2 | 3 | 4 | 5 | K到此值K-5或从该值2 | 3 | 5到2-5 ..

SUBSTRING(string_agg(DISTINCT (trim(leading '0' from sgl.short_name)),'|' )FOR 11) as GRADE

Answer 1

您不需要string_agg，但需要一个窗口功能：

SELECT DISTINCT
       CAST (first_value(short_name) OVER w AS text)
          || '-'
          || CAST(last_value(short_name) OVER w AS text)
FROM sgl
WINDOW w AS (PARTITION BY somecol ORDER BY short_name);

由于缺乏样本数据而未经测试。