MySQL子查询在3个表上返回多于1行

Question

SELECT b.bill_no, b.case_no, b.patient_id,
(Select (lastname) from myhospital.patient p where p.patient_id = b.patient_id) as l_name,
(Select (givenname) from myhospital.patient p where p.patient_id = b.patient_id) as f_name,
(Select (middle) from myhospital.patient p where p.patient_id = b.patient_id) as m_name,
(select (address_street) from myhospital.patient p where
p.patient_id = b.patient_id) as adress, m. item_name,
(select cast(m.unit_price as Char(8))) as unit_price,
(select cast(m.qty as Char(8))) as quantity,
(select cast(m.charges as Char(8))) as charges,
m.date_rec, m.service_code,
(select (descript) from myhospital.hosp_services s where m.service_code = s.service_code) as Section,
(Select (fullname) from myhospital.users u where u.user_id = m.edit_by) as Encode_by,
(Select (descript) from myhospital.hosp_bill_etc c where b.bill_no = c.bill_no) as misc_edit
FROM myhospital.hosp_bill b join myhospital.hosp_bill_meds m
where b.bill_no = m.bill_no

I have join 2 tables from 1 database and i want to add another table which is "myhospital.hosp_bill_etc" and i am getting an error

subquery returns more than 1 row,

please someone tell me how to solve this.

Answer 1

As you stated, you are obviously new to querying, and it does take practice. Start by learning the relationships between the tables, and to direct joins (or left joins) without doing repeated queries. So, the patient information should be a single record for the given "patient_id". The joins between tables needs to identify HOW they are related or you will get Cartesian results. Notice how I am showing the relationship between respective tables via the "ON" command. And for readability, notice how I am visually nesting the table relations such as from billing to bill meds to hosp services, and users etc.

Now, you can get any column from the respective table(s) in the field selection list by the simple alias... Anyhow, hopefully a little help for you... Also, I don't know why you are casting the charges, qty, price as character. Typically output to what ever would formatted there and leave original value(s) as-is.

SELECT 
      b.bill_no, 
      b.case_no, 
      b.patient_id,
      p.lastname as l_name,
      p.givenname as f_name,
      p.middle as m_name,
      p.address_street as address, 
      m. item_name,
      m.unit_price,
      m.qty as quantity,
      m.charges,
      m.date_rec, 
      m.service_code,
      s.descript as Section,
      u.fullname as Encode_by,
      c.descript as misc_edit
   FROM 
      myhospital.hosp_bill b 
         JOIN myhospital.patient p
            ON b.patient_id = p.patient_id

         JOIN myhospital.hosp_bill_meds m
            ON b.bill_no = m.bill_no
            JOIN myhospital.hosp_services s 
               ON m.service_code = s.service_code
            JOIN myhospital.users u 
               ON m.edit_by = u.user_id

         JOIN myhospital.hosp_bill_etc c 
            ON b.bill_no = c.bill_no

So this is the relationships for the tables, but it will now return ALL entries for ALL patients. If you want something for a specific bill, or patient, you would add a WHERE clause for that specific component.

Now, it appears a bill is always to a single patient. A bill has many meds. Each med I would think has a single service, but if one med can have more than one, you will get duplicates. Also, for each med, I would expect a single person associated with who recorded/distributed the meds.

Finally your "bill_etc". If this has multiple rows, that too could cause a Cartesian result.

Hopefully a good start based on YOUR data environment vs so many generics that you might have to wrap your head around, but PLEASE do some more reading on SQL practices.