"where子句"中的未知列“" [英] Unknown column '' in 'where clause'

问题描述

我的查询抛出此错误.谁能看到原因?

My query is throwing up this error. Can anyone see why?

$query = "SELECT * FROM Units WHERE ID = `$uniqueUnits[a]`";

"where子句"中的未知列"

Unknown column '' in 'where clause'

推荐答案

两个问题.

• 您正在使用反引号分隔字符串.反引号分隔字段，因此MySQL认为您正在尝试为其指定列名称.

• You're using backticks to delimit a string. Backticks delimit fields, so MySQL thinks you're trying to give it a column name.

该错误消息表示，实际上，它认为它是列名的该值是空的.因此，您的值$uniqueUnits[a]可能已损坏，或未正确插值.

The error message indicates that, in fact, this value that it thinks is a column name, is empty. So your value $uniqueUnits[a] is probably broken, or not being interpolated correctly.

您应该执行以下操作:

• 使用复杂语法"明确插入变量 ，以确保字符串格式正确；

• Interpolate your variables explictly with the "complex syntax" to be sure that the string forms properly;

检查 $query的值，以便您查看正在发生的情况:

Check the value of $query so that you can see what's going on:

print $query;

使用实际的引号分隔字符串:

Use actual quotation marks to delimit strings:

$query = "SELECT * FROM Units WHERE ID = '{$uniqueUnits[a]}'";
//                                       ^ quote
//                                        ^ PHP variable interpolation

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