Solved. Malplaced memset.... Op 07-01-2024 om 19:39 schreef Jogchum Reitsma via discuss:
Hi,
Using server version: 11.2.2, I try to extract data from a database with this C-code:
#include
#include #include #include define MAXFLEN 66
char *bo_src = "SELECT FILENAMME, FILENUM FROM BOEK WHERE TOKENS IS NULL ORDER BY UDC_KOADE, FILENUM";
char filename[MAXFLEN], stavering[3];
long filenum;
int fetch_result;
MYSQL *bo_src_sql; MYSQL_ST MT *bo_src_stmt; MYSQL_RES *bo_src_res; MYSQL_BIND bo_src_bind[2], bo_src_bind_result[2];
int main (argc, argv)
int argc; char *argv[];
{ bo_src_sql = mysql_init(bo_src_sql) ; if ((bo_src_stmt = mysql_stmt_init(bo_src_sql))==NULL) printf ("Can't initialize %s:\n %s/n", bo_src, mysql_error(bo_src_sql)) ; if (!mysql_real_connect(bo_src_sql,"localhost","<user>","<passwd>","tdb",0,NULL,0)) fprintf(stderr, "Failed to connect to book table for select: Error: %s\n", mysql_error(bo_src_sql)) ; if (mysql_stmt_prepare(bo_src_stmt, bo_src, strlen(bo_src))) printf ("Can't prepare %s:\n %s\n", bo_src, mysql_error(bo_src_sql)) ; bo_src_bind_result[0].buffer_type = MYSQL_TYPE_STRING ; bo_src_bind_result[0].buffer = filename ; bo_src_bind_result[0].buffer_length = 100 ; bo_src_bind_result[1].buffer_type = MYSQL_TYPE_LONG ; bo_src_bind_result[1].buffer = (long *)&filenum ; bo_src_bind_result[1].buffer_length = sizeof (filenum) ; memset (bo_src_bind, 0, sizeof (bo_src_bind)) ; memset (bo_src_bind_result, 0, sizeof (bo_src_bind_result)) ; if (mysql_stmt_bind_param (bo_src_stmt, bo_src_bind)) fprintf(stderr, "Failed to bind parameters in %s: \n Error: %s\n", bo_src, mysql_error(bo_src_sql)) ; if (mysql_stmt_bind_result(bo_src_stmt, bo_src_bind_result)) fprintf(stderr, "Failed to bind result in %s: \n Error: %s\n", bo_src, mysql_error(bo_src_sql)) ; if (!mysql_stmt_execute (bo_src_stmt)) { fetch_result = mysql_stmt_fetch(bo_src_stmt) ; if (fetch_result == 0) printf ("%ld %s %s\n", filenum, filename, stavering) ; else if (fetch_result == MYSQL_NO_DATA) printf ("No data found\n") ; else if (fetch_result == MYSQL_DATA_TRUNCATED) printf ("Data truncated.\n%d/n", fetch_result) ; else printf ("Something else! %d \n%s/n", fetch_result, mysql_error(bo_src_sql)); } ; mysql_stmt_close(bo_src_stmt) ; mysql_close(bo_src_sql); }
The definition of the table is
describe BOEK; +-----------+-------------------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra | +-----------+-------------------------------+------+-----+---------+----------------+
| FILENUM | smallint(4) | NO | PRI | NULL | auto_increment | | TITEL | varchar(50) | YES | | NULL | | | UDC_KOADE | varchar(10) | YES | | NULL | | | ISBN | bigint(13) | YES | | NULL | | | FILENAMME | varchar(20) | YES | | NULL | | | SKR_NUM | smallint(5) | YES | | NULL | | | UTJ_NUM | smallint(5) | YES | | NULL | | | UTJ_DATUM | date | YES | | NULL | | | OERSET | tinyint(1) | YES | | NULL | | | PRINTINGE | smallint(3) | YES | | NULL | | | YNL_DATUM | date | YES | | NULL | | | STAVERING | enum('ald','mid','nij','int') | YES | | NULL | | | TOKENS | smallint(6) | YES | | NULL | | | TYPES | smallint(5) | YES | | NULL | | | MAXTOKENS | smallint(6) | YES | | NULL | | | MAXTYPES | smallint(5) | YES | | NULL | | | TIID | time | YES | | NULL | | +-----------+-------------------------------+------+-----+---------+----------------+
So the size of FILENAMME, varchar20, is much smaller than the buffer length specified in the code:
; bo_src_bind_result[0].buffer_type = MYSQL_TYPE_STRING ; bo_src_bind_result[0].buffer = filename ; bo_src_bind_result[0].buffer_length = 100
Yet I get a MYSQL_DATA_TRUNCATED fetching the result of the query.
Debugging, only the integer filenum gets its value.
The statement (SELECT FILENAMME, FILENUM FROM BOEK WHERE TOKENS IS NULL ORDER BY UDC_KOADE, FILENUM;) gives the expected result when entered in a terminal session.
I obviously do something wrong, but I can't find out what. Googling gets me no answer.
Anyone who can spot the error?
Many thanks in advance,
best regards, Jogchum
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