Question

I am using MySQL C API.
Now I have some Double Typed data in C, and I want to insert them to a database.
All I know now is to use mysql_real_query() with a statement string to do this.
I am worrying about losing precision, since the process above involves double to string then to double. Is there a way to avoid this? Like sending double binary data directly to MySQL? I assume MySQL implements double the same as C does.

Answer 1

You should use a prepared statement with a placeholder for your double and then you can bind a double without converting anything to a string. Something like this:

char *insert = "insert into pancakes (d) values (?)";
MYSQL_BIND b;
MYSQL_STMT *stmt = mysql_stmt_init(mysql);
mysql_stmt_prepare(stmt, insert, strlen(insert));

b.buffer_type = MYSQL_TYPE_DOUBLE;
b.buffer = &your_double;
/* Fill in the rest of b...*/
mysql_stmt_bind_param(stmt, &b);

References:

• mysql_stmt_init
• mysql_stmt_prepare
• Type Codes
• mysql_stmt_bind_param