mysql - 如何编写一个查询，其中包含3个表相同的列，并执行其中一个不同的列

Question

我有3个表，其中3个表有3个相同的列名
但第三个表的第三列与第一个第二个表的列不同..
我的需要将澄清给定的图像和查询...

//this the query I'm using but not I wanted
select l.admission_number,l.student_class ,l.student_name ,l.telugu  from lkg_to_seventh_marks as l 
union all 
select e.admission_number ,e.student_class ,e.student_name ,e.telugu  from eighth_to_ninth_marks as e 
union all
select t.admission_number ,t.student_class ,t.student_name,t.telugu_1  from tenthclass_marks as t

Answer 1

尝试这样

select l.admission_number,l.student_class ,l.student_name,l.telugu,NULL as telugu_1 
from lkg_to_seventh_marks as l 
union all 
select e.admission_number ,e.student_class ,e.student_name ,e.telugu ,NULL  as telungu_1
from eighth_to_ninth_marks as e 
union all
select t.admission_number ,t.student_class ,t.student_name,NULL as telugu, t.telugu_1 
from tenthclass_marks as t

我想你想要这个查询

select l.admission_number,l.student_class ,l.student_name,cast(l.telugu as char(50))
,'NULL' as telugu_1  from lkg_to_seventh_marks as l 
union all 
select e.admission_number ,e.student_class ,e.student_name ,cast(e.telugu as char(50))
,'NULL'as telungu_1
from eighth_to_ninth_marks as e 
union all
select t.admission_number ,t.student_class ,t.student_name,'NULL'as telugu, 
cast(t.telugu_1 as char(50)) as telungu_1
rom tenthclass_marks as t