检查查询结果是否为空行 mysqli [英] check if the query results empty row mysqli

问题描述

我正在使用此代码，但我不明白如何检查查询是否返回零行.我该如何检查?

I am using this code, but I don't understand how to check if the query returns zero rows. How can I check that?

$results = $mysqli->query("SELECT ANNOUNCE_NUMBER,ANNOUNCEMENTS,ANNOUNCE_TYPE,POST_DATE FROM home WHERE ANNOUNCE_NUMBER NOT LIKE $excludewelcome AND ANNOUNCE_NUMBER NOT LIKE $excludenews ORDER BY ANNOUNCE_NUMBER DESC LIMIT $position, $items_per_group");
if ($results) { 
    //output results from database

    while($obj = $results->fetch_object())
    {
        if($obj->ANNOUNCE_TYPE=='NEWSEVENTS')
        {
            $realstring='News and Events';
        }
        else
        {
        $realstring='Welcome Note';
        }

        echo '<li id="item_'.$obj->ANNOUNCE_NUMBER.'"><strong>'.$realstring.'</strong></span>';
        echo '<br \>'; 
        echo '('.$obj->POST_DATE.' ) <span class="page_message">'.$obj->ANNOUNCEMENTS.'</span></li>';
    }

}

推荐答案

您可以使用num_rows 在数据集上检查返回的行数.示例:

You can use the num_rows on the dataset to check the number of rows returned. Example:

$results = $mysqli->query("SELECT ANNOUNCE_NUMBER,ANNOUNCEMENTS,ANNOUNCE_TYPE,POST_DATE FROM home WHERE ANNOUNCE_NUMBER NOT LIKE $excludewelcome AND ANNOUNCE_NUMBER NOT LIKE $excludenews ORDER BY ANNOUNCE_NUMBER DESC LIMIT $position, $items_per_group");
if ($results) { 

    if($results->num_rows === 0)
    {
        echo 'No results';
    }
    else
    {
        //output results from database
        while($obj = $results->fetch_object())
        {
            if($obj->ANNOUNCE_TYPE=='NEWSEVENTS')
            {
                $realstring='News and Events';
            }
            else
            {
            $realstring='Welcome Note';
            }

            echo '<li id="item_'.$obj->ANNOUNCE_NUMBER.'"><strong>'.$realstring.'</strong></span>';
            echo '<br \>'; 
            echo '('.$obj->POST_DATE.' ) <span class="page_message">'.$obj->ANNOUNCEMENTS.'</span></li>';
        }
    }
}

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