来自表的整个数据不是通过mysql中的连接查询来的

Question

i'm working with php mysql and there are 12 tables which contains student informations.There are 3 main table First table is registration, second is demandraft and third is creditcard.The demandraft table contains all the creditcard table fields but as empty. now i want to get the whole data from these three tables to generate my xls file but coz there are empty fields of creditcard table in demandraft table so unable to fetch the whole records from all 3 tables. there is stuid field common in all 3 tables.

Here is my join query for that:

$sql = "select * from  registration 
        join programme on registration.id=programme.stuid 
        join family on registration.id=family.stuid 
        join address on registration.id=address.stuid 
        join education on registration.id=education.stuid 
        join extradetail on registration.id=extradetail.stuid 
        join workexperience on registration.id=workexperience.stuid 
        join demanddraft on registration.id=demanddraft.stuid 
        join payonline on registration.id=payonline.stuid 
        where (DATE(registration.createddate)>='".$term1."' 
        AND DATE(registration.createddate)<='".$term2."')";

Answer 1

Use a left join.

select *
from a join b on a.id = b.a_id

will not list lines of table a that do not appear in table b.

select *
from a left join b on a.id = b.a_id

will.

Left join might be a bit tricky when chaining many of them with multiple tables. You may have to cleverly use parentheses around joins such that the order of joins is correct.

Answer 2

This :

$sql = "select * from  registration 
        left join programme on registration.id=programme.stuid 
        left join family on registration.id=family.stuid 
        left join address on registration.id=address.stuid 
        left join education on registration.id=education.stuid 
        left join extradetail on registration.id=extradetail.stuid 
        left join workexperience on registration.id=workexperience.stuid 
        left join demanddraft on registration.id=demanddraft.stuid 
        left join payonline on registration.id=payonline.stuid 
        where (DATE(registration.createddate)>='".$term1."' 
        AND DATE(registration.createddate)<='".$term2."')";

Should do the trick