mysql：如何从重复的行组中按2列获取最大id？

Question

I have one table name "sections_content" that has the following columns

and I want to get max id for each statecode and policyname

So ,for example,the result of statecode CN / IL /IE should be

How should I write the code for mysql ?

thanks.

Answer 1

I think you can solve this with a JOIN on the MAX for that group:

SELECT * FROM sections_content as t
JOIN
    (
        SELECT MAX(id) as id
        FROM sections_content AS tbl
        GROUP BY
            tbl.policyName,
            tbl.statecode
    ) AS maxId
    ON maxId.id=t.id

Answer 2

I think you can use ORDER BY and LIMIT keywords to get the maximum number.

Exp: Having tables; table1 and table2 as in your database. check below queries.

SELECT table1.id, table2.statecode, table2.policyname, sections_content.student_lga_of_origin 
FROM table1
JOIN table2
ON table1.policyname = table2.policyname
ORDER BY table1.id DESC
LIMIT 1
OFFSET 1