Question

你好，我有一个数据库，里面有2个表，一个是categoryTable，另一个是userMenuTable，categoryTable目前有两列， categoryId 和 categoryTitle 它目前拥有2行数据，categoryId = 1 和 2 ，categoryTitles = 新闻和博客，在 userMenuTable 中，我记录了用户选择的类别，该表有3列， menuEntryId ， categoryId 和 cookieId ，此表记录了哪个cookie选择了哪个类别，然后ID将运行这些查询，

第一个查询，获取用户选择的类别

function getMenu($cookieId) {
  $this->db->select('*');
  $this->db->from('categoryTable');
  $this->db->join('userMenuTable', 'categoryTable.categoryId = userMenuTable.categoryId', 'left');
  $this->db->where('userMenuTable.cookieId', $cookieId);

  $query = $this->db->get();
  return $query->result_array();

 }

下一个查询获取没有分配cookieId的所有类别，

function getAllMenus($cookieId) {
$sql ="SELECT categoryTable.categoryTitle, categoryTable.categoryId, userMenuTable.cookieId, userMenuTable.menuEntryId, categoryTable.categoryOnline,
categoryTable.categoryIsSpecial, categoryTable.categoryDateCreated, categoryTable.categorySlug, categoryTable.dashboardUserId, categoryTable.categoryAbstract
FROM categoryTable LEFT JOIN userMenuTable
   ON categoryTable.categoryId = userMenuTable.categoryId
 UNION ALL 
 SELECT categoryTable.categoryTitle, categoryTable.categoryId, userMenuTable.cookieId, userMenuTable.menuEntryId, categoryTable.categoryOnline,
categoryTable.categoryIsSpecial, categoryTable.categoryDateCreated, categoryTable.categorySlug, categoryTable.dashboardUserId, categoryTable.categoryAbstract FROM categoryTable RIGHT JOIN userMenuTable
   ON categoryTable.categoryId = userMenuTable.categoryId
 WHERE userMenuTable.cookieId = NULL";

$ query = $ this-＆gt; db-＆gt; query（$ sql）; return $ query-＆gt; result_array（）; }

但是这会返回一个看起来像这样的数组，

[0] => Array
    (
        [categoryId] => 1
        [categoryTitle] => blog
        [categoryAbstract] => <p>asdsdsadasdsadfdsgdgdsgdsgssssssssssss</p>
        [categorySlug] => blog
        [categoryIsSpecial] => 0
        [categoryOnline] => 1
        [categoryDateCreated] => 1265123745
        [dashboardUserId] => 0
        [menuEntryId] => 5
        [cookieId] => bang4b696152b4869
    )

[1] => Array
    (
        [categoryId] => 8
        [categoryTitle] => News
        [categoryAbstract] => <p>The world at Bang Marketing moves fast, keep up to date w
        [categorySlug] => news
        [categoryIsSpecial] => 0
        [categoryOnline] => 1
        [categoryDateCreated] => 1265283717
        [dashboardUserId] => 0
        [menuEntryId] => 6
        [cookieId] => bang4b696152b4869
    )

[2] => Array
    (
        [categoryTitle] => blog
        [categoryId] => 1
        [cookieId] => bang4b696152b4869
        [menuEntryId] => 5
        [categoryOnline] => 1
        [categoryIsSpecial] => 0
        [categoryDateCreated] => 1265123745
        [categorySlug] => blog
        [dashboardUserId] => 0
        [categoryAbstract] => <p>asdsdsadasdsadfdsgdgdsgdsgssssssssssss</p>
    )

[3] => Array
    (
        [categoryTitle] => News
        [categoryId] => 8
        [cookieId] => bang4b696152b4869
        [menuEntryId] => 6
        [categoryOnline] => 1
        [categoryIsSpecial] => 0
        [categoryDateCreated] => 1265283717
        [categorySlug] => news
        [dashboardUserId] => 0
        [categoryAbstract] => <p>The world at Bang Marketing moves fast, keep up to date w
    )
)

不知何故，我需要构建一个返回 categoryTable 中所有类别的查询，并检查其中的Id是否与 userMenuTable 中的一个匹配 cookieId 与用户的匹配，然后返回一个数组，以便我可以像这样循环它，

 if(isset($mainMenu)) {
   //die(print_r($mainMenu));
   foreach ($mainMenu as $k => $v) {
    if($v['menuEntryId'] == '') {
     echo "<li class='menuItem'>
     <a href='".base_url()."welcome/getContent/$v[categoryId]' class='navLink' id='$v[categoryTitle]'>".$v['categoryTitle']."</a>
     </li>";
    } else {
     echo "<li class='menuItem'>
     <a href='".base_url()."welcome/getContent/$v[categoryId]' class='saved navLink' id='$v[categoryTitle]'>".$v['categoryTitle']."</a>
     </li>";
    }
   }
  } else {
   // do something else
   //echo "here";
  }

Answer 1

在此处运行左连接时，您将在左侧列中获取所有categoryTable项，在userMenuTable列中获取空值。您可以使用此功能，因为尚未保存的类别将包含userMenuTable列的空值。

SELECT categoryTable.*, userMenuTable.*
FROM categoryTable LEFT JOIN userMenuTable ON categoryTable.categoryID = userMenuTable.categoryID
WHERE userMenuTable.cookieID == '{$cookieID}' OR userMenuTable.cookieID IS NULL;

这可能会给你一个看起来像这样的结果：

[0] => Array
    (
        [categoryId] => 1
        [categoryTitle] => blog
        [categoryAbstract] => <p>asdsdsadasdsadfdsgdgdsgdsgssssssssssss</p>
        [categorySlug] => blog
        [categoryIsSpecial] => 0
        [categoryOnline] => 1
        [categoryDateCreated] => 1265123745
        [dashboardUserId] => 0
        [menuEntryId] => 5
        [cookieId] => bang4b696152b4869
    )

[1] => Array
    (
        [categoryId] => 8
        [categoryTitle] => News
        [categoryAbstract] => <p>The world at Bang Marketing moves fast, keep up to date w
        [categorySlug] => news
        [categoryIsSpecial] => 0
        [categoryOnline] => 1
        [categoryDateCreated] => 1265283717
        [dashboardUserId] => 0
        [menuEntryId] => 6
        [cookieId] => bang4b696152b4869
    )

[2] => Array
    (
        [categoryId] => 9
        [categoryTitle] => Extra
        [categoryAbstract] => <p>Another category you haven't saved
        [categorySlug] => extra
        [categoryIsSpecial] => 0
        [categoryOnline] => 1
        [categoryDateCreated] => 1265283717
        [dashboardUserId] => 0
        [menuEntryId] => NULL
        [cookieId] => NULL
    )
)

PHP和mySQL的帮助

1 个答案: