Trying to truncate table but the output is Segmentation fault (core dumped).
Following is my code to truncate.
Table Name : DEPO
Since the function del_depo_data is called from different place and database is opened from where it is called so, didn't write the code to open open DB.
void del_depo_data()
{
sqlite3 *db;
char *zErrMsg = 0;
int rc;
char *sql;
sqlite3_stmt *res;
const char* data = "Callback function called";
/* Create merged SQL statement */
sql = "DELETE FROM TABLE DEPO";
rc = sqlite3_exec(db, sql, callback, (void*)data, &zErrMsg);
sqlite3_close(db);
return;
}
Solved.
Need to Open the DB inside the del_depo_data().
In the SQL Query there is a syntactical error.
Delete from DEPO will be there.
Since the function del_depo_data is called from different place and database is opened from where it is called so, didn't write the code to open open DB.
If you've opened a database somewhere else in your code, you need to pass the database handle (the sqlite3 *) to this function somehow. As it stands, you're declaring a local variable sqlite3 *db, but never initializing it to any value. This causes SQLite to crash.
Additionally, DELETE FROM TABLE tablename is not a valid SQLite syntax. The correct syntax is simply DELETE FROM tablename.
Related
I'm trying to link sqlite3 library to CMakeList in Clion using the following code:
find_package(SQLite3)
target_link_libraries(IIWProject SQLite::SQLite3)
Library has been loaded but when i Run the code, Clion shows the following error:
SQL logic error
The database has been loaded but when sqlite3_prepare_v2(db, query, -1, &stmt, NULL) was called return SQL logic error
void get_db(sqlite3 **db){
int rc;
if ((rc = sqlite3_open("db_project.db", db)) != SQLITE_OK){
//fprintf(stderr, "Failed to open DB.\n");
fprintf(stderr,"Failed to open DB: %s\n\r", sqlite3_errstr(rc));
exit(EXIT_FAILURE);
}
}
int clear_table(sqlite3 *db){
sqlite3_stmt *stmt;
int rc;
char* query = "DELETE FROM resources";
if ((rc=sqlite3_prepare_v2(db, query, -1, &stmt, NULL)) != SQLITE_OK){
fprintf(stderr,"Failed to prepare statement: %s\n\r", sqlite3_errstr(rc));
return 1;
}
if ((rc = sqlite3_step(stmt)) != SQLITE_DONE){
fprintf(stderr,"Delete failed: %s\n\r", sqlite3_errstr(rc));
return 1;
}
return 0;
}
How can I try to fix it?
EDIT:
If I compile, without Clion manually, with gcc -lsqlite3,it work
Now that we've established that the table doesn't exist when you run your program though your IDE...
The current working directory when you run your program through a command line is different than the current working directory your IDE runs it in. Since you're using a relative path to the database file, this means you're using a different one depending on how you run your program. Only one of the databases actually has the table(s) you're trying to use.
Some solutions:
Use an absolute path to the database.
Configure your IDE to use the same working directory as when you're running your program through a command line.
I have the following code:
char const* const fileName = argv[1];
FILE* file = fopen("/home/tariq/Desktop/domainlist.txt", "r");
char path[256] ;
char subpath[128];
while (fgets(path, sizeof(path), file)) {
if (fscanf(file,"%s" ,path)==1){
memcpy(subpath, &path[23], 30);
subpath[strlen(subpath)-8] = '\0';
printf("Path %s ***** SubPath %s\n", path, subpath);
}
}
As you can see, the while loops on the domainlist.txt file (which contains a list of other text files). in the variable path I store each path from the domainlist.txt and in the variable subpath I store some text from the original path. My question is that I want (instead of the printf line) to create SQLite table with a name from variable the subpath and import the data from the file in variable path.
The SQLite database is already created and a connection is open, I just want to create tables and import data into them. I tried to use termsql but all I could do is to create separate database from each file, which I don't want, I want one DB but different tables.
I hope I could describe my case correctly.
Thanks
EDIT
The content of the files to be added to the db tables are just a list of URLs. Example below:
the file (domainlist.txt) contains a list of paths,
Example of a path:
Path (which will be in the path variable):
/home/tariq/Desktop/BL/ads/domains.txt
Subpath variable (which I want to be the table name):
ads
Content of file "domains.txt" in the path above is just a list of URLs.
Assuming you haven't gotten it working yet, looking at that bit of code in your question makes me suspect you're not that strong at C yet, because there's some strange bits that don't really make any sense (Why are you reading a line with fgets() and then immediately using fscanf() to read a single word into the same variable you just read a line into? Especially when your input seems to have one filename per line? And that memcpy() will break badly if you try using files in different directories.)
That's why I suggested using a shell script. With all your information in files, it's just so much easier even if you're fluent in C.
Here's a bash-specific one:
#!/bin/bash
database=test.db
domainsfile=domainlist.txt
coproc sqlite3 -batch -list "$database"
echo "PRAGMA journal_mode = TRUNCATE;" >&${COPROC[1]}
while read filename; do
d=$(dirname "$filename")
tablename=$(basename "$d")
cat >&${COPROC[1]} <<EOF
BEGIN TRANSACTION;
CREATE TABLE IF NOT EXISTS "$tablename"(url TEXT);
.import "$filename" "$tablename"
COMMIT;
EOF
done <$domainsfile
echo .quit >&${COPROC[1]}
wait $COPROC_PID
and a less efficient (Because it runs a new instance of the sqlite3 shell per table, instead of using a single one for all of them) but more generic portable sh version:
#!/bin/sh
database=test.db
domainsfile=domainlist.txt
while read filename; do
d=$(dirname "$filename")
tablename=$(basename "$d")
sqlite3 -batch -list "$database" <<EOF
CREATE TABLE IF NOT EXISTS "$tablename"(url TEXT);
.import "$filename" "$tablename"
EOF
done <$domainsfile
However, some hints for a C version:
For each filename in domainlist.txt, extract the table name portion (The POSIX dirname() and basename() functions would be useful). Then create the table with something like:
char *errmsg;
char *table_stmt = sqlite3_mprintf("CREATE TABLE \"%s\"(url TEXT);", tablename);
if (sqlite3_exec(db, table_stmt, NULL, NULL, &errmsg) != SQLITE_OK) {
// Error handling
}
sqlite3_free(table_stmt);
and import the contents of the current file with something like:
char *insert_stmt = sqlite3_mprintf("INSERT INTO \"%s\"(url) VALUES (?)", tablename);
sqlite3_stmt *stmt;
if (sqlite3_prepare_v2(db, insert_stmt, -1, &stmt, NULL) != SQLITE_OK) {
// Error handling
}
// Open the current file
// In a loop that reads each line in it:
sqlite3_bind_text(stmt, 1, line, -1, SQLITE_STATIC);
if (sqlite3_step(stmt) != SQLITE_DONE) {
// Error handling
}
sqlite3_reset(stmt);
// After importing the file:
sqlite3_finalize(stmt);
You'll probably want to wrap each table import in a transaction, as in the bash example, or even the entire thing, for performance reasons.
I know there have been questions asked before about this problem but none seem to shine a light on my problem which is, I am trying to compile a C application and want to access SQLite from within the code (as per test app below) using Eclips as a compile and debugging environment.
I know the .h files are being accessed. the code has as many lines commented out to do with iostream as I have tried to compile this as a C++ app as well.
I get errors one for each of 2 the SQL API.
The real question is do I have to set and How do I set a dependency in Eclipse to allow the api to resolve. Thanks
the code
#include <sqlite3.h>
int main()
{
int RetVal;
RetVal = OpenDB();
return RetVal;
}
int OpenDB()
{
sqlite3 *db; // database connection
int rc; // return code
char *errmsg; // pointer to an error string
/*
* open SQLite database file test.db
* use ":memory:" to use an in-memory database
*/
rc = sqlite3_open(":memory:", &db); //fails on this line
if (rc != SQLITE_OK)
{
goto out;
}
/* use the database... */
out:
/*
* close SQLite database
*/
sqlite3_close(db); //fails on this line
return 0;
}
You need to link the sqlite3 library along with your program:
gcc main.c -lsqlite3
I'm using SQLite 3 in a C application of mine. It has worked like a charm up until now, when I've started to write unit tests. The function in question is a pretty small. It opens an in-memory database, prepares a statement and then does some stuff with it. Problem is that the app crashes with a segmentation fault at the sqlite3_prepare_v2 function call. I've tried to debug it and check to see that all arguments are valid, which they seem to be.
Below, I've pasted a minimal example which causes segfault in the same way. The backtrace lists sqlite3LockAndPrepare as the function where it crashes (called by sqlite3_prepare_v2).
As I mentioned above, I use SQLite without any problems in the rest of my app. I just can't figure out what the difference in usage is, since it's split up in several different routines which also does other stuff. The one thing I can spot is the use of an in-memory database instead of on-disk, but I tried with it on disk, and it made no difference.
#include <stdlib.h>
#include <stdio.h>
#include <sqlite3.h>
int main(void)
{
sqlite3 *db;
sqlite3_stmt **stmt;
const char *str = "CREATE TABLE Test (t1 varchar(8) NOT NULL);";
if (SQLITE_OK != sqlite3_open(":memory:", &db)) {
printf("Can't open...\n");
return 1;
}
sqlite3_prepare_v2(db, str, -1, stmt, NULL);
return 0;
}
The fourth argument to sqlite3_prepare_v2() is supposed to be a valid pointer to an sqlite3_stmt *. You are instead passing an undefined value (since your variable stmt is never initialized). (Note, too, that even if that did not crash the program, you could not receive a pointer to the prepared statement that way.)
You should do this, instead:
int main(void)
{
sqlite3 *db;
sqlite3_stmt *stmt;
const char *str = "CREATE TABLE Test (t1 varchar(8) NOT NULL);";
/* ... create database ... */
sqlite3_prepare_v2(db, str, -1, &stmt, NULL);
return 0;
}
I'm having memory management related crashes when using SQLite. It only crashes once every 30 or so tries unless I enable Guard Malloc (a test mode) in Xcode, in which case it crashes the second time I prepare a statement, 100% of the time. I think it has to do with how I'm opening or using the database, but I can't find anything wrong, BUT I'm a newbie with SQLite. Is there anything I'm forgetting?
Wrapper function for opening:
int databaseConnect(sqlite3 **db){
int rc = sqlite3_open_v2(dbURL, db, SQLITE_OPEN_READWRITE, NULL);
if(rc!=SQLITE_OK){
fprintf(stderr, "Can't open database! Error: %s\n", sqlite3_errmsg(*db));
sqlite3_close_v2(*db);
return(SQL_ERROR);
}
return NO_ERROR;
}
Wrapper function for sending commands:
int databaseCommand(char* command, sqlite3* db){
char* error = NULL;
int ret = sqlite3_exec(db, command, NULL, 0, &error);
if (ret!=SQLITE_OK){
printf("SQL command aborted. Error: %s\n", error);
return SQL_ERROR; //EDIT: this will cause the database to close later
}
if (error) sqlite3_free(error);
return NO_ERROR;
}
How I use my opening function:
//ONCE IN MAIN THREAD, BEFORE ANY OTHER THREADS:
sqlite3* db = NULL;
databaseConnect(&db);
//call databaseCommmand a few times while creating tables...
sqlite3_close_v2(db);
//ONCE PER THREAD IN OTHER THREADS:
sqlite3* db = NULL; databaseConnect(&db);
How I use sqlite3_prepare_v2 in my non-main threads (and where it crashes):
struct LinkedList* databaseSelect(char* command, sqlite3* db){
sqlite3_stmt* stmt = NULL;
int retval = retval = sqlite3_prepare_v2(db,command,(strlen(command))*sizeof(char),&stmt,NULL); //crashes here the second time I run it
if(retval!=SQLITE_OK){
printf("Selecting data from database failed! Error: %s\n", sqlite3_errmsg(db));
sqlite3_free(stmt);
return NULL; //EDIT: this will cause the database to close later
}
// Then the function does stuff involving sqlite3_column_text and sqlite3_column_int…
sqlite3_free(stmt);
// return the linked list result
}
The error I get and the part of the SQLite3 library that causes it:
EXC_BAD_ACCESS (code=1) in this part of sqlite3.c:
/*
** Create a new virtual database engine.
*/
SQLITE_PRIVATE Vdbe *sqlite3VdbeCreate(sqlite3 *db){
Vdbe *p;
p = sqlite3DbMallocZero(db, sizeof(Vdbe) );
if( p==0 ) return 0;
p->db = db;
if( db->pVdbe ){
db->pVdbe->pPrev = p; //error is right here; db->pVdbe is pointing to invalid address
}
p->pNext = db->pVdbe;
p->pPrev = 0;
db->pVdbe = p;
p->magic = VDBE_MAGIC_INIT;
return p;
}
Whenever I use sqlite3_column_text, I copy the result immediately. I do not modify the result. In databaseCommand and databaseSelect, char* command is null-terminated and valid (I checked). Each thread uses its own database handle, each connected to the same database. However, in this test case, there is only one thread connected to the database at any given time.
If there really is nothing wrong here, I have to assume that I trampled the memory elsewhere in my program, and I can't find anything in the rest of the program that even looks a bit dangerous. Plus it's suspicious that SQLite is the one thing crashing every time.
The sqlite3_prepare_v2 documentation says:
The calling procedure is responsible for deleting the compiled SQL statement using sqlite3_finalize() after it has finished with it.
sqlite3_free() can be used only for raw memory allocated with sqlite3_alloc(), or when a function such as sqlite3_exec() is documented as requiring it.
Since you are using multiple threads operating on same database just make sure you close and reopen the database from these thread after every operation. You should also try not to neglect the error condition and add the close statement there also as shown below.
if(retval!=SQLITE_OK){
printf("Selecting data from database failed! Error: %s\n", sqlite3_errmsg(db));
sqlite3_free(stmt);
sqlite3_close(your_db_ptr);
......
}
sqlite3_prepare_v2() alone just compiles the SQL but does not run it. Call sqlite3_step() on the compiled statement to run it, or use sqlite3_exec() that combines prepare+step+finalize into one function call. From here.
Hope this helps.