MySQL中出现错误"每个派生表都必须有自己的别名"

Question

SELECT   tbl_class.class_name,tbl_class.class_image,tbl_class.transid,
tbl_class.class_description, COUNT(tbl_question.class_tid) AS total, 
tbl_label.label_name,tbl_label.label_no,tbl_subject.subject_name,
tbl_subject.subject_code,tbl_question.subject_tid,tbl_class.transid AS class 
FROM 
(SELECT    tbl_class.class_name,tbl_class.class_image,tbl_class.transid, 
tbl_class.class_description, COUNT(tbl_class.transid) AS total,
tbl_label.label_name, tbl_label.label_no, tbl_subject.subject_name,
tbl_subject.subject_code, tbl_question.subject_tid,
tbl_class.transid AS class 
FROM      tbl_result 
LEFT JOIN tbl_class ON tbl_result.class_tid = tbl_class.transid 
AND       tbl_class.is_delete='N' 
AND       tbl_result.is_delete='N' 
AND       tbl_result.is_active='Active' 
JOIN      tbl_field ON tbl_field.transid = tbl_class.field_tid 
AND       tbl_field.is_delete = 'N' 
AND       tbl_field.is_active='Active' 
JOIN      tbl_label ON tbl_label.transid = tbl_field.label_tid 
AND       tbl_label.is_delete = 'N' 
AND       tbl_label.is_active='Active' 
UNION 
SELECT    tbl_class.class_name,tbl_class.class_image,tbl_class.transid, 
tbl_class.class_description, COUNT(tbl_class.transid) AS total,
tbl_label.label_name, tbl_label.label_no, tbl_subject.subject_name,
tbl_subject.subject_code, tbl_question.subject_tid,
tbl_class.transid AS class 
FROM      tbl_class 
LEFT JOIN tbl_exam_management ON tbl_exam_management.class_tid = tbl_class.transid 
AND       tbl_exam_management.is_delete='N' 
JOIN      tbl_field ON tbl_field.transid = tbl_class.field_tid 
AND       tbl_field.is_delete = 'N' 
AND       tbl_field.is_active='Active' 
JOIN      tbl_label ON tbl_label.transid = tbl_field.label_tid 
AND       tbl_label.is_delete = 'N' 
AND       tbl_label.is_active='Active')

Answer 1

，tbl_class.transid as class FROM tbl_result LEFT在tbl_result.class_tid=tbl_class.transid AND tbl_class.is_delete='N'AND tbl_result.is_deleted='N'AND tbl_result.is_active='active'将tbl_field加入tbl_field.transid=tbl_class.field_tid AND tbl_field。is_active='active'在tbl_label.transid=tbl_field.label_tid ANDtbl_label.is_delete='N'AND tbl_label.is_active='active'UNION SELECT tbl_class.class_name，tbl_class.calass_image，tbl_class.transid，tbl_class=classdescription，COUNT(tbl_class.transid(为总数，tbl_label.name，tbl_label.label_no，tbl_subject_name，tbl-subject.subject_code，tbl_question.subject_tid，tbl_class.transid as class FROM tbl_class LEFT在tbl_exam_management.class_tid=tbl_class.transid AND tbl_exami_management.is_delete='N'在tbl_field.transid=tbl_class.field_id AND tbl_field.is_delet='N'AND tbl_field.is_active='active'在tbl_label.transid=tbl_field.label_tid AND tbl_label.is_delete='N'ANDtbl_label.is_active="活动"(

您必须为此子查询提供别名