閱讀本文前，請先閱讀：WordPress全域資料庫物件$wpdb – 資料查詢 在上面的文章裏，我們學會了基本的資料查詢(SELECT)，也就是CRUD操作的Read功能。

// Select/Read
function myFunction() {
 
  global $wpdb;
 
  $wpdb->get_var("Query");
  $wpdb->get_row("Query", Format_parameter);
  $wpdb->get_col("Query");
  $wpdb->get_results("Query", Format_parameter);
 
}

Create/Insert

類似SQL的insert 語法：INSERT INTO table_name (cols) VALUES (vals)

global $wpdb;

$wpdb->insert( $table, $data, $format );

例：

global $wpdb;

$wpdb->insert($wpdb->prefix."posts", array(
   	"post_title" => "Sample Post", 
    "post_content" => "This is sample content of this post",
    "post_name" => "sample-post",
    "post_status" => "publish"
),array(
   "%s",
   "%s",
   "%s",
   "%s"
));

// SQL Insert寫法：
// INSERT INTO wp_posts ("post_title", "post_content", "post_name", "post_status") 
// VALUES ("Sample Post", "This is sample content of this post", "sample-post", "publish");

第三個參數$format非必要，若給的話，以上的例子來說%s是指字串，其他還有：

1. %d – Integer Value
2. %f – Float Value etc.

  不給第三個參數的例子：

global $wpdb;

$wpdb->insert($wpdb->prefix."posts", array(
   	"post_title" => "Sample Post", 
        "post_content" => "This is sample content of this post",
        "post_name" => "sample-post",
        "post_status" => "publish"
));

當$wpdb->insert執行完畢之後，可以透過$wpdb->insert_id取得自動增號的ID值。

global $wpdb;

$row_id = $wpdb->insert($wpdb->prefix."posts", array(
   	"post_title" => "Sample Post", 
    "post_content" => "This is sample content of this post",
    "post_name" => "sample-post",
    "post_status" => "publish"
));

echo $wpdb->insert_id; // It prints the return row ID after insertion.

除了使用$wpdb->insert方法，我們也可以用query字串的方式 (通用的SQL敘述)做到一樣的功能：

global $wpdb;

$query = $wpdb->prepare('INSERT INTO wp_posts ("post_title", "post_content", "post_name", "post_status") VALUES ("Sample Post", "This is sample content of this post", "sample-post", "publish")');
$data = $wpdb->query($query);

echo $wpdb->insert_id;

Update

語法

global $wpdb;

$wpdb->update($table, $data, $where, $format = null, $where_format = null);

參數解釋

• $table – 資料表格
• $data – 要更新的資料
• $where – 條件式
• $format – 資料的格式字串 %s：字串/string, %d：整數/integer, %f：浮點數/float
• $where_format – Where字句的格式字串

範例：

global $wpdb;

$wpdb->update( 
  $wpdb->prefix."posts", 
  array(
    "post_title" => "Updated Post Title", 
    "post_content" => "This is sample content update of this post", 
    "post_name" => "my-updated-post", 
    "post_excerpt" => "Sample content update"
  ), 
  array("ID" => 4), 
  array("%s", "%s", "%s","%s"), 
  array("%d") 
);

  可以用SQL查詢字串的方式來做到上面的功能： 語法

global $wpdb;

$wpdb->prepare("UPDATE table_name SET COLS = VALS WHERE CONDITIONS");

  範例：

global $wpdb;

$sql = 'UPDATE wp_posts SET post_title = "Updated Post title", post_content = "Updated Sample content", post_name = "updated-post-name" WHERE ID = 4';

$prepared_query = $wpdb->preapre($query);

$data = $wpdb->query($prepared_query);

 

Delete

語法

global $wpdb;

$wpdb->delete(string $table, array $where, array|string $where_format = null)

範例

global $wpdb;

$wpdb->delete(
  $wpdb->prefix."posts",
  array("ID" => 4),
  array("%d")
);

用SQL查詢字串的方式來做到上面的功能：

global $wpdb
  
$query = "DELETE FROM wp_posts WHERE ID = 4";

$prepared_query = $wpdb->preapre($query);

$data = $wpdb->query($prepared_query);