SQL-重复的行SQL查询

Question

我有一个问题，它打印这个SQL语句重复的行是烦人此结果是我的SQL语句：

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 

和它打印像下面

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" 

，我想它来打印此类似：

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功能和除去叔他从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 

f.first_name对于Postgres使用array_to_string和array_agg。对于说明检查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