Php SQL查询中的常量
如何在SQL查询中使用常量?在som搜索之后,我发现了一个使用串联的技巧,比如:Php SQL查询中的常量,php,Php,如何在SQL查询中使用常量?在som搜索之后,我发现了一个使用串联的技巧,比如:。DB_TABLE.但这不起作用,因为我遇到了这样的错误:致命错误:在 这不起作用: $sql_col_1 = "SELECT * FROM" . DB_TABLE . "WHERE id BETWEEN 1 AND 11 ORDER BY RAND() ;"; 但这确实: $sql_col_1 = "SELECT * FROM buildings WHERE id BETWEEN 1 AND 11 ORDER
。DB_TABLE.
但这不起作用,因为我遇到了这样的错误:致命错误:在
这不起作用:
$sql_col_1 = "SELECT * FROM" . DB_TABLE . "WHERE id BETWEEN 1 AND 11 ORDER BY RAND() ;";
但这确实:
$sql_col_1 = "SELECT * FROM buildings WHERE id BETWEEN 1 AND 11 ORDER BY RAND() ;";
您在
DB\u TABLE
前后遗漏了一个空格:
$sql_col_1 = "SELECT * FROM " . DB_TABLE . " WHERE id BETWEEN 1 AND 11 ORDER BY RAND() ;";
^ ^
对于您的原始代码,如果DB_表是,比如说建筑物,那么您的代码将被重写为(在连接之后):
^这就是SQL导致错误的原因
将来调试此功能最简单的方法就是
echo
out$sql\u col\u 1
。添加echo$sql\u col\u 1;退出代码>紧接着,将显示正在运行的实际查询。在FROM
之后和之前需要空格
echo $sql_col_1 = "SELECT * FROM " . DB_TABLE . " WHERE id BETWEEN 1 AND 11 ORDER BY RAND()";
^^ ^^
您的查询失败,您出现致命错误 $DB_TABLE='user'
然后$sql\u col\u 1=“选择*FROM”$DB_表。“其中,id介于1和11之间,顺序为RAND();”代码>
echo $sql_col_1 = "SELECT * FROM " . DB_TABLE . " WHERE id BETWEEN 1 AND 11 ORDER BY RAND()";
^^ ^^