codeigniter mysql sql 查询

Question

Hello everyone which MySQL query that can output with my example and how i can echo. i need help here's example..

                'table 1
                | id |date        |
                | 1  |01/01/2015  |
                | 2  |01/02/2015  |
                | 3  |01/01/2015  |
                | 4  |01/02/2015  | 

                'table 2
                |id |table1_id| value1| value2| 
                | 1 |   1     |  5    |    2  |
                | 2 |   2     |  40   |    3  |
                | 3 |   3     |   5   |    2  |
                | 4 |   4     |       |    4  | 

output must

          $value_total = value1 * value2;

          if(value1 == ''){

          }else{
           $value_total = value1 * value2;
           }

Here's The final output. will add with the same date

         date           value
         01/01/2015     20
         01/02/2015     120

Answer 1

Try this:

if(!empty(value1){
    $value_total = value1 * value2;
}

Answer 2

SELECT t1.date, (t2.value1*t2.value2) As V FROM `table2` as t2
INNER JOIN table1 as t1
On t1.id=t2.table1_id
GROUP by t1.date

Answer 3

You can get the expected output by the following query.Please try this and post your comments.

SELECT 
    `t1`.`date`, 
    (`t2`.`value1`*`t2`.`value2`) as value 
FROM
    `table2` as t2
JOIN 
    `table1` as t1 
ON
    `t1`.`id` = `t2`.`table1_id` 
GROUP BY
    `date` 

Or:

SELECT * FROM `table1` as t1 JOIN `table2` as t2 ON `t1`.`id` = 't2'.`table1_id` GROUP BY `date`

and in your php get the value1 and value 2 values and check in if condition like

if (!empty($value1)) {
    echo $totalValue = $value1 * $value2;
}

Answer 4

Mysql query in Codeigniter style

$this->db->select('date, sum(t2.value1 * t2.value2) AS value', FALSE)->from('table1 t1');
$this->db->join("table2 t2", "t1.id=t2.table1_id", "LEFT");
$this->db->group_by('date');
$result = $this->db->get();