php - Codeigniter php 上的数据库错误

Question

Cannot add or update a child row: a foreign key constraint fails (warehouse_inventory_system.inventory_products, CONSTRAINT fk_category FOREIGN KEY (Category_Id) REFERENCES category (Category_Id)) INSERT INTO inventory_products (Product_Name, Category_Id, Brand_Name, Unit_Price, Date_of_Entry, Quantity) VALUES (0, 0, '1', '120', '2016-03-31', '12')

运行的代码是

<?php
 $query = $this->db->query('SELECT * FROM category');

 foreach ($query->result() as $row) {
     echo '<option value="'. $row->Category_Id. '">'. $row->Category_Name. '</option>';

  }
?>

Insert code is:
function create(){
        $this->form_validation->set_rules('Unit_Price','Unit_Price','trim|xss_clean|numeric|is_natural_no_zero|min_length[2]');

        $this->form_validation->set_rules('Quantity','Quantity','trim|xss_clean|numeric|is_natural_no_zero');

        if ($this->form_validation->run() == FALSE)
        {
            $this->index();
        }

        else
        {
            $data = array(
            'Product_Name' => $this->input->post('Product_Name'),
            'Category_Id' => $this->input->post('Category_Id'),
            'Brand_Name' => $this->input->post('Brand_Name'),
            'Unit_Price' => $this->input->post('Unit_Price'),
            'Date_of_Entry' => $this->input->post('Date_of_Entry'),
            'Quantity' => $this->input->post('Quantity')
            );

            $this->Admin_model->add_items($data);

            $this->index();

        }
    }
Admin_model
function add_items($data){
    $this->db->insert('inventory_products', $data);
    return;
}

Answer 1

您正在尝试将新记录插入 inventory_products表 category_id等于 0 并且因为 inventory_products指category表category中没有记录如果表的category_id = 0，它会抛出外键约束失败错误。

检查您的<input>和<select>并确保他们的name属性与您在 PHP 代码中读到的属性相匹配。例如:必须有<select>标签名称 Category_Id .