尝试找到空列值的MySQL语法错误

Question

我试图通过检查以查看字段是否为NULL或为空：

 $query = $this->pdo->prepare('SELECT * FROM `' . $this->table . '` WHERE `wp_permalink` IS NOT NULL AND `wp_permalink` <> "" AND `id` != 2 AND `ga_page_views` != ' . $nogo . ' ORDER BY ga_page_views DESC LIMIT 6');

如何解决wp_permalink <>“”的语法错误？谢谢您的帮助。我还在学习。

Answer 1

像这样更改代码。

$query = $this->pdo->prepare('SELECT * FROM `' . $this->table . '` WHERE `wp_permalink` IS NOT NULL AND `wp_permalink` <> \'\' AND `id` != 2 AND `ga_page_views` != ' . $nogo . ' ORDER BY ga_page_views DESC LIMIT 6');

单引号用于指示SQL中字符串的开头和结尾。在SQL中通常不使用双引号，但是每个数据库的双引号可能会有所不同。

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difference between single and double quotes in SQL

Answer 2

字符串文字用单引号引起来

wp_permalink IS NOT NULL and wp_permalink <> ''
-- Single quotes-----------------------------^^