C传递字符串进行查询，并检查结果是否为空(C pass string to query and also check if result is empty)

C传递字符串进行查询，并检查结果是否为空(C pass string to query and also check if result is empty)

当使用C连接到数据库时，我需要将一个字符串传递给查询内部，但由于我很长一段时间没有使用C，所以我不知道正确的方法。 我尝试了以下但是这不起作用。

if (mysql_query(conn, "select * from t1 where c1 = %s and c2 = %s", sptr->name, sptr->desc)) { fprintf(stderr, "%s\n", mysql_error(conn)); exit(1); }

还有什么是检查查询是否返回空结果集的最简单方法？

I need to pass a string to inside the query when connecting to a database using C, but since I have not been using C for a long time I don't know the correct way to do it. I tried the below but that doesn't work.

if (mysql_query(conn, "select * from t1 where c1 = %s and c2 = %s", sptr->name, sptr->desc)) { fprintf(stderr, "%s\n", mysql_error(conn)); exit(1); }

also what is the easiest method to check whether the query returned an empty result set?

最满意答案

IIRC，你不能直接在mysql_query()函数中使用格式说明符和相应的参数。

你需要做的是

分配一个临时缓冲区。 使用snprintf()在缓冲区中打印查询命令 使用缓冲区作为第二个参数调用mysql_query() 。

IIRC, you cannot use format specifiers and corresponding arguments directly inside mysql_query() function.

What you need to do is

Allocate one temporary buffer. use snprintf() to print the query command in the buffer call mysql_query() with the buffer as second argument.