Question

我正在使用codeigniter。我想要一个where子句来获取totalQuantity小于alterQuantity的产品。我在select子句中使用sum来获得totalQuantity。

$this->db->select("products.id as productid, products.code, products.name, products.unit, products.cost, products.price, sum(whs_products.quantity) as totalQuantity, products.alert_quantity as alertQuantity")
->from('products')
->where('alertQuantity <=', 'totalQuantity')
->join('whs_products', 'whs_products.product_id=products.id', 'left')
->group_by("products.id");
$this->db->get();

我不确定如何获得所需的产品:( 编辑如果试过这个

->where('alertQuantity <=', 'totalQuantity')

我得到所有产品但是 - ＆gt; where（'alertQuantity＆lt; ='，'totalQuantity'）没有产品。

Answer 1

只需在select语句中添加FALSE并尝试

$this->db->select("products.id as productid, products.code, products.name, products.unit, products.cost, products.price, sum(whs_products.quantity) as totalQuantity, products.alert_quantity as alertQuantity",FALSE)

$ this-＆gt; db-＆gt; select（）接受可选的第二个参数。如果你设置它为FALSE，CodeIgniter不会试图保护你的领域或表带反叛的名字。如果您需要复合选择，这非常有用言。

来自文件here

Answer 2

试试这个：

SELECT p.id AS productid, p.code, p.name, p.unit, p.cost, p.price, wp.quantity AS totalQuantity, p.alert_quantity AS alertQuantity
FROM products p 
LEFT JOIN (SELECT product_id, SUM(quantity) quantity 
              FROM whs_products GROUP BY product_id) wp ON wp.product_id = p.id AND p.alert_quantity <= quantity ;

Answer 3

试试这个

$this->db->select("products.id as productid, products.code, products.name, products.unit, products.cost, products.price, sum(whs_products.quantity) as totalQuantity, products.alert_quantity as alertQuantity")
->from('products')
->join('whs_products', 'whs_products.product_id=products.id', 'left')
->where('alertQuantity <= totalQuantity')
->group_by("products.id");
$this->db->get();

echo $this->db->last_query();exit; //to check the query generated is  correct or not

其中SUM（table1.field）＆gt; = table2.field在连接表中

3 个答案: