我正在开发一个iPad应用程序。
我的资源文件夹中有一个SQLite数据库。
当我的应用程序启动时,这些代码将数据库复制到我的NSDocumentDirectory。无法从SQLite数据库检索值
- (void) copyDatabaseIfNeeded {
NSFileManager *fileManager = [NSFileManager defaultManager];
NSError *error;
NSString *dbPath = [self getDBPath];
BOOL success = [fileManager fileExistsAtPath:dbPath];
if(!success) {
NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"Mydata.sqlite"];
success = [fileManager copyItemAtPath:defaultDBPath toPath:dbPath error:&error];
if (!success)
NSAssert1(0, @"Failed to create writable database file with message '%@'.", [error localizedDescription]);
}
}
- (NSString *) getDBPath {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory , NSUserDomainMask, YES);
NSString *documentsDir = [paths objectAtIndex:0];
return [documentsDir stringByAppendingPathComponent:@"Mydata.sqlite"];
}
在我的应用程序的另一种观点,我有这些代码来打开数据库和检索一些值。
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDir = [paths objectAtIndex:0];
if(sqlite3_open([[documentsDir stringByAppendingPathComponent:@"Mydata.sqlite"] UTF8String], &db) != SQLITE_OK){
sqlite3_close(db);
NSAssert(0, @"Failed to open database.");
}
NSString *sql = [[NSString alloc] initWithFormat:@"SELECT HOMEONE, HOMETWO, HOMETHREE, HOMEFOUR FROM STUDENTS WHERE NAME='%@'",Name];
sqlite3_stmt *statement;
if(sqlite3_prepare_v2(db, [sql UTF8String], -1, &statement, nil)== SQLITE_OK)
{
while(sqlite3_step(statement) == SQLITE_ROW){
char *one = (char *) sqlite3_column_text(statement,0);
ActionOne = [[NSString alloc] initWithUTF8String:one];
char *two = (char *) sqlite3_column_text(statement,1);
ActionTwo = [[NSString alloc] initWithUTF8String:two];
char *three = (char *) sqlite3_column_text(statement,2);
ActionThree = [[NSString alloc] initWithUTF8String:three];
char *four = (char *) sqlite3_column_text(statement,3);
ActionFour = [[NSString alloc] initWithUTF8String:four];
}
sqlite3_finalize(statement);
}
是的,使用这些代码,我可以从数据库中检索值。
但现在我需要检索更多的值,所以我编辑了我的代码。
NSString *sql = [[NSString alloc] initWithFormat:@"SELECT HOMEONE, HOMETWO, HOMETHREE, HOMEFOUR, VOICEONE, VOICETWO, VOICETHREE, VOICEFOUR FROM STUDENTS WHERE NAME='%@'",Name];
sqlite3_stmt *statement;
if(sqlite3_prepare_v2(db, [sql UTF8String], -1, &statement, nil)== SQLITE_OK)
{
while(sqlite3_step(statement) == SQLITE_ROW){
char *one = (char *) sqlite3_column_text(statement,0);
ActionOne = [[NSString alloc] initWithUTF8String:one];
char *two = (char *) sqlite3_column_text(statement,1);
ActionTwo = [[NSString alloc] initWithUTF8String:two];
char *three = (char *) sqlite3_column_text(statement,2);
ActionThree = [[NSString alloc] initWithUTF8String:three];
char *four = (char *) sqlite3_column_text(statement,3);
ActionFour = [[NSString alloc] initWithUTF8String:four];
char *vone = (char *) sqlite3_column_text(statement,4);
VoiceOne = [[NSString alloc] initWithUTF8String:vone];
char *vtwo = (char *) sqlite3_column_text(statement,5);
VoiceTwo = [[NSString alloc] initWithUTF8String:vtwo];
char *vthree = (char *) sqlite3_column_text(statement,6);
VoiceThree = [[NSString alloc] initWithUTF8String:vthree];
char *vfour = (char *) sqlite3_column_text(statement,7);
VoiceFour = [[NSString alloc] initWithUTF8String:vfour];
}
sqlite3_finalize(statement);
}
现在它甚至不检索HOMEONE,HOMETWO,HOMETHREE,HOMEFOUR值。 我试着改变我的SQL语句来检索VOICEONE,VOICETWO,VOICETHREE,VOICEFOUR值,但它也没有给我任何值。
我做了一些检查,发现该应用程序甚至没有踏进这行:
if(sqlite3_prepare_v2(db, [sql UTF8String], -1, &statement, nil)== SQLITE_OK)
这意味着sqlite3_prepare_v2不成功? 我检查了数据库字段类型。
我试图在'SQLite数据库浏览器'中执行SQL语句,并且它能够返回值。
我可以知道我的代码有什么问题吗?
我认为代码中没有主要问题请使用数据库验证下面字段的拼写。 VOICEONE,VOICETWO,VOICETHREE,VOICEFOUR – objectivecdeveloper