Insert character into MYSQL table using C++

Question

The codes below inserts values into MYSQL database. If i use "sprintf(Query, "INSERT into t(d) values (%c)", a);" it wont insert the word hello into my database. i have also tried using (%s) in the above statement. However, if i use "sprintf(Query, "INSERT into t(d) values (%d)", b);" it inserts the values 1234 into the database.

What is happening? Why wont it insert character's or string into my database but only integers?

The column d is my database is defined as char type.

Thanks.

#include "stdafx.h"
#include <stdio.h>
#include <mysql.h> 
//#include <string>
//using std::string;
//#include <atlstr.h>

MYSQL *pConnection;
MYSQL_RES *pResult=NULL; 
MYSQL_ROW Row;
char Query[256];

int main(int argc, char* argv[])
{
    pConnection = mysql_init(NULL);

    mysql_real_connect(pConnection,"localhost","root","y123","test",0,NULL,0); 

char a[] ="Hello"; 
int b = 1234;
printf("%s", a);

sprintf(Query, "INSERT into t(d) values (%s)", a);
mysql_query(pConnection, Query);

}

What types is you column You trying to insert?

aambrozkiewicz
– aambrozkiewicz

2012-03-12 14:20:12 +00:00
Commented Mar 12, 2012 at 14:20 — aambrozkiewicz
– aambrozkiewicz, Commented Mar 12, 2012 at 14:20

Marc B · Accepted Answer · 2012-03-12 14:20:23Z

4

You still need to write properly formatted queries. Yours is lacking strings around the inserted value:

sprintf(Query, "INSERT into t(d) values ('%s')", a);
                                         ^--^-- missing

Your version was generating something like

INSERT INTO t(d) values (foo);

almost certainly your table does not have a field named foo, so the query would fail and return a 'false' value. Since you had no error checking whatsoever, you'd never have noticed things were failing.

NEVER assume a query succeeds. ALWAYS check return values for success/failure. Even if your SQL is 100% perfect and valid, it can still fail for any number of other reasons.

answered Mar 12, 2012 at 14:20

Marc B

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Comments

Some programmer dude · Accepted Answer · 2012-03-12 14:20:08Z

2

SQL strings needs to be inside single quotes:

sprintf(Query, "INSERT into t(d) values ('%s')", a);
// Note the single quotes ---------------^--^

answered Mar 12, 2012 at 14:20

Some programmer dude

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