HPUNIX & SYBASE ASE12.5 ESQL多线程连接数据库有关问题

intconnect(const char* username, const char* password, const char* database){    EXEC SQL BEGIN DECLARE SECTION;    char    strUsername[DC_NAMSIZ];    char    strPassword[DC_NAMSIZ];    char    strDatabase[DC_NAMSIZ];    char    strConnection[DC_NAMSIZ];    EXEC SQL END DECLARE SECTION;    memset(strUsername, 0x00, sizeof(strUsername));    memset(strUsername, 0x00, sizeof(strPassword));    memset(strDatabase, 0x00, sizeof(strDatabase));    memset(strConnection, 0x00, sizeof(strConnection));    sprintf(strUsername, "%s", username);    sprintf(strPassword, "%s", password);    sprintf(strDatabase, "%s", database);    EXEC SQL WHENEVER SQLERROR CALL errHandler();    EXEC SQL WHENEVER SQLWARNING CALL msgHandler();    EXEC SQL WHENEVER NOT FOUND CONTINUE;    pthread_mutex_lock(&mtx);    EXEC SQL CONNECT :strUsername IDENTIFIED BY :strPassword;    EXEC SQL USE :strDatabase;    pthread_mutex_unlock(&mtx);    printf("connected.\n");       if ( sqlca.sqlcode != 0 )        return FAILURE;       EXEC SQL EXECUTE IMMEDIATE "set chained off";       return SUCCEED;}

void*qthread(void* args){    EXEC SQL BEGIN DECLARE SECTION;    char    strGroup[DC_NAMSIZ];    EXEC SQL END DECLARE SECTION;    char    strUsername[DC_NAMSIZ];    char    strPassword[DC_NAMSIZ];    char    strDatabase[DC_NAMSIZ];    int     semid = ((thread_args*)args)->semid;    int     msqid = ((thread_args*)args)->msqid;    memset(strUsername, 0x00, sizeof(strUsername));    memset(strPassword, 0x00, sizeof(strPassword));    memset(strDatabase, 0x00, sizeof(strDatabase));    sprintf(strUsername, ((thread_args*)args)->username);    sprintf(strPassword, ((thread_args*)args)->password);    sprintf(strDatabase, ((thread_args*)args)->database);    if ( FAILURE == connect(strUsername, strPassword, strDatabase) )    {        printLog(__FILE__, __LINE__, "连接数据库失败，请检查用户名/密码！");        return NULL;    }        ...