MySql query in same column for different date - php

Question

Please consider: I am talking about MySQL Database
I have two tables like this:
tbl_stock_info
+-----+--------+
| sId | sName |
+-----+--------+
| 1 | Apple |
| 2 | Google |
| 3 | Yahoo |
+-----+--------+
tbl_stock_data
+------------+----------+-------------+
| date | stock_id | stock_price |
+------------+----------+-------------+
| 2017-01-25 | 1 | 44.7 |
| 2017-01-25 | 3 | 51 |
| 2017-01-25 | 2 | 71.5 |
| 2017-01-24 | 1 | 44.9 |
| 2017-01-24 | 3 | 51.2 |
| 2017-01-24 | 2 | 71.3 |
+------------+----------+-------------+
The Output I am looking for is like this:
+-----+--------+----------+----------+
| sId | sName | Price_25 | Price_24 |
+-----+--------+----------+----------+
| 1 | Apple | 44.7 | 44.9 |
| 2 | Google | 71.5 | 71.3 |
| 3 | Yahoo | 51 | 51.2 |
+-----+--------+----------+----------+
Any assistance would be greatly appreciated.

Answer 1

You can do it with a query like this. it search the newest 2 dates in the table and generate your query, but the column name are fix. if you want also to change them you must use a prepared statement.
SELECT
si.*
,SUM(if(sd1.`date` = ( SELECT DISTINCT `date` FROM tbl_stock_data ORDER BY `date` DESC LIMIT 0,1), sd1.stock_price ,0) ) as lastday
,SUM(if(sd1.`date` = ( SELECT DISTINCT `date` FROM tbl_stock_data ORDER BY `date` DESC LIMIT 1,1), sd1.stock_price ,0) ) as daybefore
FROM tbl_stock_info si
LEFT JOIN tbl_stock_data sd1 ON sd1.stockid = si.sId
GROUP BY si.sId;
sample
MariaDB [l]> SELECT * FROM tbl_stock_info;
+-----+--------+
| sId | sNAme |
+-----+--------+
| 1 | Apple |
| 2 | Google |
| 3 | Yahoo |
+-----+--------+
3 rows in set (0.00 sec)
MariaDB [l]> SELECT * FROM tbl_stock_data;
+----+------------+---------+-------------+
| id | date | stockid | stock_price |
+----+------------+---------+-------------+
| 1 | 2017-01-25 | 1 | 44.70 |
| 2 | 2017-01-25 | 3 | 51.00 |
| 3 | 2017-01-25 | 2 | 71.50 |
| 4 | 2017-01-24 | 1 | 44.90 |
| 5 | 2017-01-24 | 3 | 51.20 |
| 6 | 2017-01-24 | 2 | 71.30 |
| 7 | 2017-01-23 | 1 | 99.00 |
| 8 | 2017-01-22 | 2 | 22.00 |
| 9 | 2017-01-20 | 3 | 33.13 |
+----+------------+---------+-------------+
9 rows in set (0.01 sec)
test
MariaDB [l]> SELECT
-> si.*
-> ,SUM(if(sd1.`date` = ( SELECT DISTINCT `date` FROM tbl_stock_data ORDER BY `date` DESC LIMIT 0,1), sd1.stock_price ,0) ) as lastday
-> ,SUM(if(sd1.`date` = ( SELECT DISTINCT `date` FROM tbl_stock_data ORDER BY `date` DESC LIMIT 1,1), sd1.stock_price ,0) ) as daybefore
-> FROM tbl_stock_info si
-> LEFT JOIN tbl_stock_data sd1 ON sd1.stockid = si.sId
-> GROUP BY si.sId;
+-----+--------+---------+-----------+
| sId | sNAme | lastday | daybefore |
+-----+--------+---------+-----------+
| 1 | Apple | 44.70 | 44.90 |
| 2 | Google | 71.50 | 71.30 |
| 3 | Yahoo | 51.00 | 51.20 |
+-----+--------+---------+-----------+
3 rows in set (0.00 sec)
MariaDB [l]>