Question

我对这个SQL语句有一个问题，它打印带有重复行的结果，这在我的SQL语句中很烦人：

SELECT
week_day,
exam_date ,
s.name ,
l.lgna_name
,f.first_name
FROM
fci_exam_time_table_line,
fci_subject s ,
fci_staff f,
lgna_lgna l 
WHERE
exam_id =%d 
GROUP BY
week_day,
exam_date ,
s.name ,
l.lgna_name ,
f.first_name
ORDER BY
exam_date

并打印如下

week_day|  exam_date |name|lgna_name|first_name

"monday";"2015-04-13";"12";   "12"  ;"12"
"monday";"2015-04-13";"12";   "12"  ;"323"
"monday";"2015-04-13";"12";   "232" ;"12"
"monday";"2015-04-13";"12";   "232" ;"323"
"monday";"2015-04-14";"12";   "12"  ;"12"
"monday";"2015-04-14";"12";   "12"  ;"323"
"monday";"2015-04-14";"12";   "232" ;"12"
"monday";"2015-04-14";"12";   "232" ;"323"

我希望它打印出来像：

week_day|  exam_date |name|lgna_name|first_name

"monday";"2015-04-13";"12";   "12"  ;"12,323"
"monday";"2015-04-13";"12";   "232";"12,323"
"monday";"2015-04-14";"12";   "12"  ;"12,323"
"monday";"2015-04-14";"12";   "232" ;"12,323"

Answer 1

使用Group_Concat功能，然后从f.first_name

中删除Group by

SELECT week_day, 
       exam_date, 
       s.name, 
       l.lgna_name, 
       Group_conact(f.first_name, ',') 
FROM   fci_exam_time_table_line, 
       fci_subject s, 
       fci_staff f, 
       lgna_lgna l 
WHERE  exam_id =% d 
GROUP  BY week_day, 
          exam_date, 
          s.name, 
          l.lgna_name 
ORDER  BY exam_date

Postgres使用array_to_string和array_agg。有关解释，请查看here

select ...
       array_to_string(array_agg(f.first_name), ',')
FROM   fci_exam_time_table_line, 
       fci_subject s, 
       fci_staff f, 
       lgna_lgna l 
WHERE  exam_id =% d 
GROUP  BY week_day, 
          exam_date, 
          s.name, 
          l.lgna_name 
ORDER  BY exam_date

SQL-Duplicated行Sql Query

1 个答案: