I have 2 tables : registered_students
- cols: regnum AND student
- cols: regnum, name
So I'm working on a query to select from both tables. It's working so far, but now I want to add a where clause to it, and it's not returning any rows. Here is the query
SELECT registered_students.regnum
, student.name
FROM registered_students
INNER JOIN student ON registered_students.regnum=student.regnum
example data:
registered_students 1).reg3030 2). reg4032
student 1).reg3030 John Doe 2).reg4032 Luke White
So I need to add a where clause like WHERE regnum LIKE 'reg4%'
You will have to specify the alias as the column has same name in both the tables, try the following query:
SELECT registered_students.regnum, student.name
FROM registered_students JOIN student ON registered_students.regnum=student.regnum
WHERE registered_students.regnum LIKE 'reg4%';
The output will also depend on the availability of data with reg4
in both the tables. You could try the following if the above does not work:
WHERE LOWER(registered_students.regnum) LIKE 'reg4%'
LEFT JOIN
if you want the data from either of these tables Update
With the updated data, it might be because of whitespace or a dot in the beginning of the value, I would try the following:
SELECT registered_students.regnum, student.name
FROM registered_students JOIN student ON TRIM(registered_students.regnum) = TRIM(student.regnum)
WHERE registered_students.regnum LIKE '%reg4%';
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.