使用PHP时出现奇怪的语法错误MySQL错误

Question

我在这段代码中的第1行附近有语法错误：

//...
$nr = 126;
$expl = "'test'";
$da = "'2003-12-01'";
$tax = 2.5;
$cost = 100;

//Here is the error
$sql = "INSERT INTO tbl (type, nr, explan, date, tax, cost) VALUES('Example'," + $nr + ",'"+ $expl + "','" + $da + "'," + $tax + "," + $cost + ");";

这是错误日志：

Error: 103.5
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '103.5' at line 1

我使用的是PHP版本5.6.3和MySQL版本5.6.21

我无法弄清楚，问题是什么：（

Answer 1

您正在使用+来连接字符串，这在PHP中不起作用。您必须使用.。

可能有一些奇怪的算术会产生103.5，就像2.5 + "," + 100一样。将","转换为int(1)或其他内容的位置。