Question

执行rc = sqlite3_open（“test.db”，＆amp; db）时，我“无法打开数据库文件”; ??

sqlite3 *db; // sqlite3 db struct
char *zErrMsg = 0;
int rc;

// Open the test.db file
rc = sqlite3_open("test.db", &db); // <-- creates DB if not found ??

if( rc ){
    // failed
    fprintf(stderr, "ERROR: Can't open database: %s\n", sqlite3_errmsg(db));
}

Answer 1

如果数据库尚不存在，

sqlite3_open将返回错误。要创建数据库（如果该数据库尚不存在），请使用带有sqlite3_open_v2和SQLITE_OPEN_CREATE标记的SQLITE_OPEN_READWRITE（两者都是）：

rc = sqlite3_open_v2(/* DB Path */, &db, SQLITE_OPEN_CREATE | SQLITE_OPEN_READWRITE, NULL);

Reference

要查找/* DB PATH */，您需要将文件名基于文档目录：

- (NSString *) applicationDocumentsDirectory 
{    
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *basePath = ([paths count] > 0) ? [paths objectAtIndex:0] : nil;
    return basePath;
}

您可以使用此便捷方法将文档路径与数据库名称组合在一起：

NSString *documents = [self applicationDocumentsDirectory];
NSString *dbPath = [documents stringByAppendingPathComponent:@"test.db"];

rc = sqlite3_open_v2([dbPath UTF8String], &db, SQLITE_OPEN_CREATE | SQLITE_OPEN_READWRITE, NULL);

Answer 2

#define SQLITE_OK 0
sqlite3 *db;
char *zErrMsg=0;
if(sqlite3_open("demo.db", &db) == SQLITE_OK)
{
    if(sqlite3_exec(db, "select * from Users", callback, 0, &zErrMsg) == SQLITE_OK)
            msgbox1("success");
    sqlite3_close(db);
}
else
    msgbox1("failure");

这是我使用的示例代码;

sqlite3_open：“无法打开数据库文件”

2 个答案: