从三个不同的表中获取总视图

Question

大家好，我是 Codeigniter 初学者，

在控制器中，我正在发送数据，如-

1

$send['rowa'] = $this->db->query("
SELECT sum(views) as rowCount 
  from table_a
")->result();

2

$send['rowb'] = $this->db->query("
SELECT sum(view_counter) as rowCount 
  from table_b
")->result();

3

$send['rowc'] = $this->db->query("
SELECT sum(view_counter) as rowCount 
  from table_c
")->result();

鉴于我正在使用

'<=$rowa[0]->rowCount;?>, <=$rowb[0]->rowCount;?>, <=$rowc[0]->rowCount;?>.

我得到的实际输出类似于

12, 34, 21.

我想得到

的总数

12+34+21= 67.

我怎样才能得到它？

谢谢大家

Answer 1

你可以使用

$send['total'] = $this->db->query("SELECT (SELECT sum(views) as rowCount from table_a)+(SELECT sum(view_counter) as rowCount from table_b)+(SELECT sum(view_counter) as rowCount from table_c) as rowCount;")->result();

哪个会运行

SELECT 
(SELECT sum(views) as rowCount from table_a) 
+(SELECT sum(view_counter) as rowCount from table_b)
+(SELECT sum(view_counter) as rowCount from table_c) as rowCount;

因为每个 select 只有 returns 1 个结果这可以用来添加结果

从三个不同的表中获取总视图

Get Total View from three different tables

mysql

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