php - MySQL 括号？

Question

最近我看到了很多将 SQL 值包含在 {} 中的 PHP/MySQL 问题，例如:

SELECT * FROM table WHERE field LIKE '{$value}';

这是怎么回事？它甚至有效吗？为什么这么多人使用这种奇怪的(至少对我而言)语法？

Answer 1

来自 php.net :

Complex (curly) syntax

This isn't called complex because the syntax is complex, but because it allows for the use of complex expressions.

In fact, any value in the namespace can be included in a string with this syntax. Simply write the expression the same way as it would appear outside the string, and then wrap it in { and }. Since { can not be escaped, this syntax will only be recognised when the $ immediately follows the {. Use {\$ to get a literal {$.