使用 c++ 创建一个 sqlite3 表

Question

I know their is another question with this exact title but it doesn't solve my problem, so here goes.

I am following a tutorial on using SQLite with c++, but when I run my program to create the database table, I get an error;

static int create_database(const char *s);
static int create_table(const char *s);

int main(){
    const char *file = "Mafia.sqlite";
    sqlite3 *db;

    create_database(file);
    create_table(file);
}

static int create_database(const char* s){
    sqlite3 *db = NULL;
    int query = 0;

    query = sqlite3_open_v2(s, &db, SQLITE_OPEN_CREATE, NULL);
    cout << "Database created successfully!\n";
    sqlite3_close(db);

    return 0;
}

static int create_table(const char* s){
    sqlite3 *db;

    string sql = "CREATE TABLE IF NOT EXISTS USERS("
                "ID INTEGER PRIMARY KEY AUTOINCREMENT,"
                "USERNAME TEXT NOT NULL,"
                "PASSWORD TEXT NOT NULL);";

    try{
       int query = 0;
       query = sqlite3_open_v2(s, &db, SQLITE_OPEN_READWRITE, NULL);

       char *error_message;
       query = sqlite3_exec(db, sql.c_str(), NULL, 0, &error_message);

       if(query != SQLITE_OK){
           cerr << "Error occurred creating table!\n";
           sqlite3_errmsg(db);
           sqlite3_free(error_message);
       }else
           cout << "Table created successfully\n";
       sqlite3_close(db);
    }
    catch(const exception &e){
        cerr << e.what() << '\n';
    }

}

My terminal returns the following:

Database created successfully!
Error occurred creating table!
test(13698,0x109148dc0) malloc: Non-aligned pointer 0x102bd9641 being freed
test(13698,0x109148dc0) malloc: *** set a breakpoint in malloc_error_break to debug

Edit I corrected the sql error and I still have the same problem

Thanks.

Answer 1

There are couple of things,

First you need to initialize error_message to nullptr . Otherwise sqlite3_free will cause a crash since error_message is having some garbage value.

Secondly, according to the SQLITE documentation , you need to use atleast one of the three options while opening an SQLITE connection,

1. SQLITE_OPEN_READONLY
2. SQLITE_OPEN_READWRITE
3. SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE

You are not supposed to use SQLITE_OPEN_CREATE as a standalone option. If you change these two, it should work fine.