Arduino mysql connector: char pointer value to char array

Projects Programming
1

I use the library mysql connector for arduino (you can download it from manage-libraries).

The problem is that if I put a value to char array:

char charbuffer[30] = "bbb";

I can send query like this:

char INSERT_DATA[] = "INSERT INTO arduino.sensors_data (sid, address) VALUES (%d,'%s')";

sprintf(query, INSERT_DATA, vsid, charbuffer);

BUT if I try get variable from address:

    char* getAddress() const { 
      return address;
    }

and use

strcpy(charbuffer, sensors[i]->getAddress());

It not work.

Any ideas what could affect this problem? (all other things works fine and return method has no problems. Seems that strcpy not work but also I m not sure how could i put this char const* value to char array[30]). It not also help if I use %s, not '%s'.

2

You are simply trying to load this array:
char charbuffer[30]
with a value that is in, or is pointed at by, sensor[1] ?

Can you post the code which includes the definition of sensor and, if sensor is an array of structures, the definition of that structure, and the code which updates sensor.

3

"It does not work" is not enough for us to help you.

What is the result in charbuffer of this operation...

strcpy(charbuffer, sensors[i]->getAddress());

? Nothing? Something odd?

4 
char charbuffer[30];
memset(charbuffer, '\0', sizeof(charbuffer));
strcpy(charbuffer, sensors[i]->getAddress());

Serial monitor: (it puts only the first value). I used '%s' for query.

Connected to server version 5.6.21 (this print is from mysql-connector-library that connection is ok)
0 (for loop for sensors) - Serial.println(i);
28 A8 FB 13 5 0 0 B0 - Serial.println(charbuffer);
28 A8 FB 13 5 0 0 B0 - Serial.println(charbuffer)(before sql-query)
28 A8 FB 13 5 0 0 B0 - Serial.println(charbuffer)(after all)
1
28 2B 4F 13 5 0 0 53
28 2B 4F 13 5 0 0 53 (before sql-query)
Error: 156 = 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 '[' at line 1.
28 2B 4F 13 5 0 0 53

Now it puts only the first value to a database but gets problems after that. It works fine (puts data all time to the database) if I determine char charbuffer[30] = "whatevervalue";

5

We need to see ALL of your code.

6

I figured out what was a problem. Was thinking about this why it gives error about '['. Then I was thinking that there was not enough space for query.

So when I changed

char sqlquery[200];

it started working. All examples with mysql-connector have char sqlquery[128];

So not remembered change it.

7

tolerance_zero:
I figured out what was a problem. Was thinking about this why it gives error about '['. Then I was thinking that there was not enough space for query.

So when I changed

char sqlquery[200];

it started working. All examples with mysql-connector have char sqlquery[128];

You'd do well to have a define of the max size somewhere so you can change all your character arrays at once if you need to in the future....

#define SQL_SIZE_MAX 200


char Query1[SQL_SIZE_MAX+1] ; // +1 for terminating zero
char AQuery[SQL_SIZE_MAX+1] ;
etc...

So if you ever have to change the size again all you need to do is change 200 to, for example, 250...