如何通过变量的mysql_query [英] How to pass variable in mysql_query

问题描述

我试图执行MySQL查询传递变量。这里是我的code

I try to execute mysql query passing variable. Here is my code

char str[100] = "My String";

mysql_query(conn, printf("INSERT INTO table VALUES %s"), str);

我得到在编译过程中警告

I get that warning during compile process

warning: passing argument 2 of ‘mysql_query’ makes pointer from integer without a cast

我错过了什么？

推荐答案

您不能这样做。 的printf（）返回打印的字符数。您有的mysql_query（）调用之前创建字符串：

You cannot do that. printf() returns the number of characters printed. You have to create the string before calling mysql_query():

char statement[512], *my_str = "MyString";
snprintf(statement, 512, "INSERT INTO table VALUES ('%s')", str);
mysql_query(conn, statement);

此外，在创建这些查询字符串时要小心。不要使用类似函数的sprintf（）如果你不能确定得到的字符串有多长。不要过度的内存段的边界写。

Also, be careful when creating those query strings. Don't use functions like sprintf() if you cannot be sure how long the resulting string is. Don't write over the boundaries of the memory segment.

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