<ruby id="bdb3f"></ruby>

    <p id="bdb3f"><cite id="bdb3f"></cite></p>

      <p id="bdb3f"><cite id="bdb3f"><th id="bdb3f"></th></cite></p><p id="bdb3f"></p>
        <p id="bdb3f"><cite id="bdb3f"></cite></p>

          <pre id="bdb3f"></pre>
          <pre id="bdb3f"><del id="bdb3f"><thead id="bdb3f"></thead></del></pre>

          <ruby id="bdb3f"><mark id="bdb3f"></mark></ruby><ruby id="bdb3f"></ruby>
          <pre id="bdb3f"><pre id="bdb3f"><mark id="bdb3f"></mark></pre></pre><output id="bdb3f"></output><p id="bdb3f"></p><p id="bdb3f"></p>

          <pre id="bdb3f"><del id="bdb3f"><progress id="bdb3f"></progress></del></pre>

                <ruby id="bdb3f"></ruby>

                企業??AI智能體構建引擎,智能編排和調試,一鍵部署,支持知識庫和私有化部署方案 廣告
                **1. DML操作** DML操作是指:insert(新增)、update(修改)、delete(刪除),直接操作數據,結構不變。 <br/> **2. 視圖的DML操作** 因為視圖本身沒有數據,因此對視圖進行的 DML 操作最終都體現在基表中。 ```sql # 1. 基表的數據 mysql> select * from author; +----+-------------+ | id | author_name | +----+-------------+ | 1 | 張三 | | 2 | 李四 | | 3 | 王五 | | 4 | 趙六 | +----+-------------+ # 2. 創建視圖 mysql> create view v_author as select * from author with check option; # 3. 對視圖進行 update mysql> update v_author set author_name='張33' where id=1; # 4. 再查看基表的數據,被更新了 mysql> select * from author; +----+-------------+ | id | author_name | +----+-------------+ | 1 | 張33 | | 2 | 李四 | | 3 | 王五 | | 4 | 趙六 | +----+-------------+ ``` **3. 如果定義視圖的`select`語句包含下面子句之一,則不能對視圖進行DML操作** ``` – select子句中包含distinct – select子句中包含組函數 – select語句中包含group by子句 – select語句中包含order by子句 – select語句中包含union 、union all等集合運算符 – where子句中包含相關子查詢 – from子句中包含多個表 – 如果視圖中有計算列,則不能更新 – 如果基表中有某個具有非空約束的列未出現在視圖定義中,則不能做insert操作 ```
                  <ruby id="bdb3f"></ruby>

                  <p id="bdb3f"><cite id="bdb3f"></cite></p>

                    <p id="bdb3f"><cite id="bdb3f"><th id="bdb3f"></th></cite></p><p id="bdb3f"></p>
                      <p id="bdb3f"><cite id="bdb3f"></cite></p>

                        <pre id="bdb3f"></pre>
                        <pre id="bdb3f"><del id="bdb3f"><thead id="bdb3f"></thead></del></pre>

                        <ruby id="bdb3f"><mark id="bdb3f"></mark></ruby><ruby id="bdb3f"></ruby>
                        <pre id="bdb3f"><pre id="bdb3f"><mark id="bdb3f"></mark></pre></pre><output id="bdb3f"></output><p id="bdb3f"></p><p id="bdb3f"></p>

                        <pre id="bdb3f"><del id="bdb3f"><progress id="bdb3f"></progress></del></pre>

                              <ruby id="bdb3f"></ruby>

                              哎呀哎呀视频在线观看