SQLITE Blob写入错误 [英] SQLITE Blob writing error
问题描述
下面是一段代码，用于在SQLITE中编写和读取blob
数据库。
我从blob结构中读取一个名为''点的问题''
任何帮助将不胜感激
Reagards
格雷格
＃ include< stdlib.h>
#include< stdio.h>
#include< string.h>
#include< ; assert.h>
#include" sqlite3.h"
typedef unsigned char uchar;
char dbname [1000];
static sqlite3 * db1;
void
exec_simple（char * stm）
{
int rc;
char * errMsg = 0;
rc = sqlite3_exec（db1，stm， NULL，0，& errMsg）;
if（rc！= SQLITE_OK）
{
fprintf（stderr，" SQL error： ％s \ n"，errMsg）;
}
}
typedef struct points
{
long numPoints;
double * x;
}积分;
int
main（int argc，char ** argv）
{
char * errMsg = 0;
int rc;
sqlite3_stmt * stmt = NULL;
积分*积分;
长numPoints;
长尺寸;
int iii;
char text [32];
uchar * pabyRec;
int nRecordSize;
int num_punkt;
int nOffset;
strcpy（dbname，" .\\test.db"）;
unlink（dbname）;
rc = sqlite3_open（dbname，& db1）;
if（rc）
{
fprintf（stderr，无法打开数据库：％s \ n，sqlite3_errmsg（db1））;
退出（1）;
}
exec_simple（" PRAGMA page_size = 8192"）;
exec_simple（" PRAGMA synchronous = OFF"）;
exec_simple（" PRAGMA count_changes = OFF"）;
exec_simple（" PRAGMA temp_ store = MEMORY"）;
exec_simple（" CREATE TABLE punkty（id INTEGER PRIMARY KEY，value BLOB）"）;
//写记录
numPoints = 5;
size = numPoints * 1 * sizeof（double）+ sizeof（int）;
pointsP = （积分*）malloc（大小）;
memcpy（pointsP，& numPoints，sizeof（int））;
nRecordSize = 4 ;
pointsP-> x =（double *）calloc（numPoints，sizeof（double））;
for（iii = 0 ; iii<为NumPoints; iii ++）
{
pointsP-> x [iii] =（double）iii * 100 + 0.01;
}
for（iii = 0; iii< numPoints; iii ++）
{
memcpy（pointsP + nRecordSize，pointsP-> x + iii，sizeof（double））;
nRecordSize + = 1 * 8;
}
rc = sqlite3_prepare（db1， 插入punkty值（1，？）;"，-1，& stmt，
NULL）;
if（rc）
{
fprintf（stderr，" ERORR：％s \ n"，sqlite3_errmsg（db1））;
exit（1）;
}
rc = sqlite3_bind_blob（stmt，1，pointsP，size，NULL）;
if（rc）
{
fprintf（stderr，" ERORR：％s \ n"，sqlite3_errmsg（db1））;
exit（1）; < br $>
}
sqlite3_step（stmt）;
rc = sqlite3_finalize（stmt）;
if（rc）
{
fprintf（stderr，" ERORR：％s \ n"，sqlite3_errmsg（db1））;
退出（1）;
}
if（pointsP-> x！= NULL）
{
免费（ pointsP-> x）;
pointsP-> x = NULL;
}
免费（pointsP）;
pointsP = NULL;
//读取记录
rc = sqlite3_prepare（db1，" select * from punkty"，-1，& stmt，NULL）;
if（rc！= SQLITE_OK）
{
fprintf（stderr，" ％s \ n"，sqlite3_errmsg（db1））;
}
while（sqlite3_step（stmt）== SQLITE_ROW）
{
if（rc！= SQLITE_OK）
{
fprintf（stderr，" SQL error：％s \ n"，errMsg）;
}
size = sqlite3_column_bytes（stmt，1）;
pointsP =（Points *）malloc（size）;
memcpy（pointsP，sqlite3_column_blob（stmt，1），size）;
printf（" size =％ld \ n"，size）;
memcpy（& num_punkt，pointsP，4）;
printf（" pointsP-> numPoints =％ld \ n"，num_punkt）;
nOffset = 4;
pointsP-> x = （double *）calloc（num_punkt，sizeof（double））;
for（iii = 0; iii< num_punkt; iii ++）
{
memcpy（pointsP-> x + iii，pointsP + nOffset + iii * 8,8）; //也许在这里
是一个错误
}
for（iii = 0; iii< num_punkt; iii ++）
{
printf（" x =％。2f \ nn"，pointsP-> x [iii]）; //这里打印垃圾
}
printf（" ID =％ld \ n"，sqlite3_column_int（stmt，0））;
}
sqlite3_finalize（stmt）;
}
Here is a piece of code below for writing and reading blobs in SQLITE
database.
I '' ve a problem to read from blob struct called ''Points''
Any help would be appreciated
Reagards
Greg
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "sqlite3.h"
typedef unsigned char uchar;
char dbname[1000];
static sqlite3 *db1;
void
exec_simple (char *stm)
{
int rc;
char *errMsg = 0;
rc = sqlite3_exec (db1, stm, NULL, 0, &errMsg);
if (rc != SQLITE_OK)
{
fprintf (stderr, "SQL error: %s\n", errMsg);
}
}
typedef struct points
{
long numPoints;
double *x;
}Points;
int
main (int argc, char **argv)
{
char *errMsg = 0;
int rc;
sqlite3_stmt *stmt = NULL;
Points *pointsP;
long numPoints;
long size;
int iii;
char text[32];
uchar *pabyRec;
int nRecordSize;
int num_punkt;
int nOffset;
strcpy(dbname,".\\test.db");
unlink (dbname);
rc = sqlite3_open (dbname, &db1);
if (rc)
{
fprintf (stderr, "Can''t open database: %s\n", sqlite3_errmsg (db1));
exit (1);
}
exec_simple ("PRAGMA page_size=8192");
exec_simple ("PRAGMA synchronous = OFF");
exec_simple ("PRAGMA count_changes = OFF");
exec_simple ("PRAGMA temp_store = MEMORY");
exec_simple ("CREATE TABLE punkty(id INTEGER PRIMARY KEY, value BLOB)");
// write record
numPoints=5;
size = numPoints * 1 * sizeof(double) + sizeof(int);
pointsP = (Points *) malloc(size);
memcpy( pointsP, &numPoints, sizeof(int));
nRecordSize = 4;
pointsP->x = (double *) calloc(numPoints, sizeof(double));
for( iii = 0; iii < numPoints; iii++ )
{
pointsP->x[iii] = (double)iii*100+0.01;
}
for( iii = 0; iii < numPoints; iii++ )
{
memcpy( pointsP + nRecordSize, pointsP->x + iii, sizeof(double));
nRecordSize += 1 * 8;
}
rc = sqlite3_prepare(db1, "insert into punkty values (1,?);", -1, &stmt,
NULL);
if (rc)
{
fprintf (stderr, "ERORR: %s\n", sqlite3_errmsg (db1));
exit (1);
}
rc =sqlite3_bind_blob(stmt, 1, pointsP, size, NULL);
if (rc)
{
fprintf (stderr, "ERORR: %s\n", sqlite3_errmsg (db1));
exit (1);
}
sqlite3_step(stmt);
rc =sqlite3_finalize(stmt);
if (rc)
{
fprintf (stderr, "ERORR: %s\n", sqlite3_errmsg (db1));
exit (1);
}
if( pointsP->x != NULL )
{
free( pointsP->x );
pointsP->x=NULL;
}
free(pointsP);
pointsP=NULL;
// read record
rc = sqlite3_prepare (db1, "select *from punkty", -1, &stmt, NULL);
if (rc != SQLITE_OK)
{
fprintf (stderr, " %s\n", sqlite3_errmsg (db1));
}
while (sqlite3_step (stmt) == SQLITE_ROW)
{
if (rc != SQLITE_OK)
{
fprintf (stderr, "SQL error: %s\n", errMsg);
}
size = sqlite3_column_bytes(stmt, 1);
pointsP= (Points *)malloc(size);
memcpy(pointsP,sqlite3_column_blob(stmt, 1),size);
printf("size=%ld\n",size);
memcpy( &num_punkt, pointsP, 4 );
printf("pointsP->numPoints=%ld\n",num_punkt);
nOffset = 4;
pointsP->x = (double *) calloc(num_punkt, sizeof(double));
for( iii = 0; iii < num_punkt; iii++ )
{
memcpy(pointsP->x + iii, pointsP + nOffset + iii * 8, 8); //maybe here
is a fault
}
for(iii=0;iii<num_punkt;iii++)
{
printf("x=%.2f\n",pointsP->x[iii]); // here prints rubbish
}
printf("ID=%ld\n", sqlite3_column_int(stmt,0));
}
sqlite3_finalize (stmt);
}
推荐答案
11月14日，5：41 * am，向导 < g ... @ wp.plwrote：
On Nov 14, 5:41*am, "wizard" <g...@wp.plwrote:
下面是一段代码，用于在SQLITE中编写和读取blob
数据库。
我从blob结构中读取一个名为''积分'的问题'
任何帮助将不胜感激
Reagards
Greg
#include< stdlib.h>
#include< stdio.h>
#include< string.h>
#include< assert.h>
#include" sqlite3.h"
typedef unsigned char uchar;
char dbname [1000];
static sqlite3 * db1;
void
exec_simple（char * stm）
{
* int rc;
* char * errMsg = 0;
* rc = sqlite3_exec（db1，stm，NULL，0，& errMsg）;
* if（rc！= SQLITE_OK）
* {
* * fprintf（stderr，SQL错误：％s \ n"，errMsg）;
* }
}
typedef struct points
{
long numPoints;
double * x;
}积分;
int
main（int argc，char ** argv）
{
* char * errMsg = 0;
* int rc;
* sqlite3_stmt * stmt = NULL;
* Points ** pointsP;
*长numPoints;
*长尺寸;
* int iii;
*字符文本[32] ;
* * uchar * pabyRec;
* * int * * * * nRecordSize;
int num_punkt;
int nOffset;
* strcpy（dbname，" .\\test.db"）;
* unlink（dbname ）;
* rc = sqlite3_open（dbname，& db1）;
* if（rc）
* {
* * fprintf（stderr，无法打开数据库：％s \ n，sqlite3_errmsg（db1））;
* *退出（1）;
*}
* exec_simple（" PRAGMA page_size = 8192"）;
* exec_simple（" ; PRAGMA同步s = OFF"）;
* exec_simple（" PRAGMA count_changes = OFF"）;
* exec_simple（" PRAGMA temp_store = MEMORY"）;
* exec_simple（" CREATE TABLE punkty（id INTEGER PRIMARY KEY，value BLOB）"）;
//写记录
* numPoints = 5;
* size = numPoints * 1 * sizeof（double）+ sizeof（int）;
* pointsP =（Points *）malloc（size）;
Here is a piece of code below for writing and reading blobs in SQLITE
database.
I '' ve a problem to read from blob struct called ''Points''
Any help would be appreciated
Reagards
Greg
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "sqlite3.h"
typedef unsigned char uchar;
char dbname[1000];
static sqlite3 *db1;
void
exec_simple (char *stm)
{
* int rc;
* char *errMsg = 0;
* rc = sqlite3_exec (db1, stm, NULL, 0, &errMsg);
* if (rc != SQLITE_OK)
* {
* * fprintf (stderr, "SQL error: %s\n", errMsg);
* }
}
typedef struct points
{
long numPoints;
double *x;
}Points;
int
main (int argc, char **argv)
{
* char *errMsg = 0;
* int rc;
* sqlite3_stmt *stmt = NULL;
* Points **pointsP;
* long numPoints;
* long size;
* int iii;
* char text[32];
* * uchar *pabyRec;
* * int * * * * nRecordSize;
int num_punkt;
int nOffset;
* strcpy(dbname,".\\test.db");
* unlink (dbname);
* rc = sqlite3_open (dbname, &db1);
* if (rc)
* {
* * fprintf (stderr, "Can''t open database: %s\n", sqlite3_errmsg (db1));
* * exit (1);
* }
* exec_simple ("PRAGMA page_size=8192");
* exec_simple ("PRAGMA synchronous = OFF");
* exec_simple ("PRAGMA count_changes = OFF");
* exec_simple ("PRAGMA temp_store = MEMORY");
* exec_simple ("CREATE TABLE punkty(id INTEGER PRIMARY KEY, value BLOB)");
// write record
* numPoints=5;
* size = numPoints * 1 * sizeof(double) + sizeof(int);
* pointsP = (Points *) malloc(size);
不要施放malloc！我不明白计算尺寸的b $ b。为什么乘以一？为什么要添加sizeof（int）？
如果你想要pointsP {能够有numPoints积分，
只需使用：
pointsP = malloc（numPoints * sizeof（* pointsP））;
Don''t cast malloc! And I don''t understand the computation
of size. Why multiply by one? why add sizeof(int)?
If you want pointsP{ to be able to have numPoints Points,
just use:
pointsP = malloc( numPoints * sizeof(*pointsP) );
>
* memcpy（pointsP，& ; numPoints，sizeof（int））;
>
* memcpy( pointsP, &numPoints, sizeof(int));
我不知道你为什么要这样做，但这可能是错的。
numPoints很长。为什么你只复制它的一部分？
I don''t know why you are doing this, but it is probably wrong.
numPoints is a long. why are you copying only part of it?
>
* nRecordSize = 4;
* * pointsP-> x =（double *）calloc（numPoints，sizeof（double））;
>
* nRecordSize = 4;
* * pointsP->x = (double *) calloc(numPoints, sizeof(double));
pointsP-> x = calloc（numPoints，sizeof（* points） - > x））;
pointsP->x = calloc(numPoints, sizeof(*points)->x) );
>
* for（iii = 0; iii< numPoints; iii ++）
* * {
* pointsP- > x [iii] =（double）iii * 100 + 0.01;
*}
* for（iii = 0; iii< numPoints; iii ++）
* {
* * memcpy（pointsP + nRecordSize，pointsP-> x + iii，sizeof（double））;
* * nRecordSize + = 1 * 8;
*}
>
*for( iii = 0; iii < numPoints; iii++ )
* * {
* pointsP->x[iii] = (double)iii*100+0.01;
*}
*for( iii = 0; iii < numPoints; iii++ )
*{
* * memcpy( pointsP + nRecordSize, pointsP->x + iii, sizeof(double));
* * nRecordSize += 1 * 8;
*}
现在你将一个双重复制到一个长的中间，
可能会破坏某些东西。你要做的是什么？
Now you are copying a double into the middle of a long,
probably clobbering something. What is it you are trying to do?
（snip）
(snip)
-
Fred Kleinschmidt
--
Fred Kleinschmidt
Fred< fr ***************** @ boeing.comwrites：
Fred <fr*****************@boeing.comwrites:
11月14日，5：41？* am，向导 < g ... @ wp.plwrote：
On Nov 14, 5:41?*am, "wizard" <g...@wp.plwrote:
< snip>
<snip>
>？*？* pointsP-> x =（double *）calloc（numPoints，sizeof（double））;
>?* ?* pointsP->x = (double *) calloc(numPoints, sizeof(double));
pointsP-> x = calloc（numPoints，sizeof（* points） - > x））;
pointsP->x = calloc(numPoints, sizeof(*points)->x) );
你可能打算输入：
pointsP-> x = calloc（numPoints，sizeof（* pointsP-> ; x）））;
-
Ben。
You probably meant to type:
pointsP->x = calloc(numPoints, sizeof(*pointsP->x)) );
--
Ben.
" wizard" < gg ** @ wp.plwrites：
"wizard" <gg**@wp.plwrites:
下面是一段代码，用于在SQLITE
数据库中编写和读取blob。
Here is a piece of code below for writing and reading blobs in SQLITE
database.
这个界面的细节在这里是偏离主题的，但我认为
你的第一个问题与C和内存有关分配。
< snip>
The details of that interface would be off-topic here, but I think
your first problems are just to do with C and memory allocation.
<snip>
typedef struct points
{
long numPoints;
double * x ;
}积分;
typedef struct points
{
long numPoints;
double *x;
}Points;
< snip>
<snip>
numPoints = 5;
size = numPoints * 1 * sizeof（double）+ sizeof（int）;
pointsP =（Points *）malloc（size）;
numPoints=5;
size = numPoints * 1 * sizeof(double) + sizeof(int);
pointsP = (Points *) malloc(size);
这都错了。首先，我将乘法乘以1和
不必要的演员。然后我将不得不问你想要的数据是什么？
写入这个blob。如果你真的需要一个双*，那么
你需要为这个结构分配空间+也许一些填充*房间
5个双打。测试程序中的一种方法是：
struct blob {
积分p;
double actual_points [5] ;
};
并分配其中一个：
struct blob * bp = malloc（sizeof * bp）;
bp-> p.numPoints = 5;
bp-> px = bp-> actual_points;
当然，你很可能在Points结构中想要双打
，在这种情况下，typedef是错误的你和
应该搜索struct hack。
This is all wrong. First, I''d remove the multiplication by 1 and the
unnecessary cast. Then I''d have to ask what data you are trying to
write into this "blob". If you really need a double * in there, then
you need to allocate space for this struct + maybe some padding * room
for 5 doubles. One way to do that in the test program is:
struct blob {
Points p;
double actual_points[5];
};
and to allocate one of these:
struct blob *bp = malloc(sizeof *bp);
bp->p.numPoints = 5;
bp->p.x = bp->actual_points;
Of course, it is just as likely that you really wanted the doubles to
in the Points struct, in which case the typedef is wrong and you
should search for the "struct hack".
memcpy（pointsP，& numPoints，sizeof（int））;
memcpy( pointsP, &numPoints, sizeof(int));
哇！ sizeof（int）并不总是sizeof（long）。为什么不：
pointsP-> numPoints = numPoints;
？
Woah! sizeof(int) is not always sizeof(long). Why not:
pointsP->numPoints = numPoints;
?
nRecordSize = 4;
pointsP-> x =（double *）calloc（numPoints，sizeof（double））;
nRecordSize = 4;
pointsP->x = (double *) calloc(numPoints, sizeof(double));
执行两次分配后，我认为您无法将
点数据转换为单个blob。现在，这可能是这样的，但是我怀疑它是怎么回事。
After doing two allocations, I think you will not be able to get the
points data into a single "blob". Now, it could be that this is how
SQLite3 works, but I doubt it.
for（iii = 0; iii< numPoints; iii ++）
{
pointsP-> x [iii] =（double）iii * 100 + 0.01;
for( iii = 0; iii < numPoints; iii++ )
{
pointsP->x[iii] = (double)iii*100+0.01;
演员是不必要的。
The cast is unnecessary.
}
for（iii = 0; iii< numPoints; iii ++）
{
memcpy（pointsP + nRecordSize，pointsP-> x + iii，sizeof（double））;
nRecordSize + = 1 * 8;
}
for( iii = 0; iii < numPoints; iii++ )
{
memcpy( pointsP + nRecordSize, pointsP->x + iii, sizeof(double));
nRecordSize += 1 * 8;
这都错了。我不能纠正它，因为我不知道是什么
" shape"您真正想要制作的数据。你首先需要告诉我们
。
and this is all wrong. I can''t correct it because I don''t know what
"shape" of data you are really trying to make. You need to tell us
that first of all.
}
}
< snip>
-
Ben。
<snip>
--
Ben.
这篇关于SQLITE Blob写入错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
