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我有一个SQLite数据库为我的应用程序。从db中检索实体我使用这种方法:objective-c sqlite3数据库更改不持久
- (sqlite3*) openDatabaseNamed:(NSString*)databaseName
{
if(![databaseName isEqualToString:kTopInternationalDatabaseName] &&
![databaseName isEqualToString:kTop500RODatabaseName]){
NSAssert(nil, @"Database does not exist!");
}
sqlite3 * dataBase;
NSString * path;
path = [[NSBundle mainBundle] pathForResource:databaseName ofType:@"sqlite3"];
if (sqlite3_open([path UTF8String], &dataBase) != SQLITE_OK) {
NSString * errorString = [NSString stringWithFormat:@"[SQLITE] Unable to open database <%@> ",databaseName];
NSAssert(nil,errorString);
}
return dataBase;
}
- (NSArray *) getAllEntitiesForDatabaseNamed:(NSString*)databaseName
{
(...)
sqlite3 * database = [self openDatabaseNamed:databaseName];
NSMutableArray *retval = [[NSMutableArray alloc] init];
NSString *query = [NSString stringWithFormat:@"SELECT * FROM %@",databaseName];
NSArray *properties = [entityClass classProperties];
if (sqlite3_prepare_v2(database, [query UTF8String], -1, &statement, nil)
== SQLITE_OK) {
while (sqlite3_step(statement) == SQLITE_ROW) {
for (int i=2; i<countLimit; i++){
chars = (char *) sqlite3_column_text(statement,i+1);
if(chars != NULL)
{
containerString = [NSString stringWithUTF8String:chars];
if(containerString && containerString.length>0){
[entityModel setValue:containerString forKey:properties[i]];
}
}
}
[retval addObject:entityModel];
}
sqlite3_finalize(statement);
}
sqlite3_close(database);
return retval.copy;
}
一切都按预期工作。为了将实体的自定义字段设置为数据库中的特定值,我使用此方法:
- (void)setEntity:(EntityModel *)entity favorite:(BOOL)favorite
{
NSString *query = [NSString stringWithFormat:@"UPDATE %@ SET favorite = %i WHERE position = '%i';",kDatabaseName,favorite?1:0,entity.positionInTop];
sqlite3_stmt *statement;
sqlite3 * database = [self openDatabaseNamed:kTop500RODatabaseName];
if (sqlite3_prepare_v2(database, [query UTF8String], -1, &statement, nil)
== SQLITE_OK) {
sqlite3_step(statement);
sqlite3_finalize(statement);
}
sqlite3_close(database);
}
发生的事情有点奇怪。如果我使用更新方法并且在使用getAllEntitiesForDatabaseNamed
的所有实体的应用查询的同一生命周期中,我对setEntity:Favorite:
所做的更改仍然存在。另一方面,如果我使用更新方法,然后关闭应用程序并重新启动它,则使用setEntity:Favorite:
所做的更改将丢失。任何想法是为什么?
PS:我也用sqlite3_exec
试过,仍然结果是相同的:
if (sqlite3_exec(database, [query UTF8String], NULL, NULL, NULL) != SQLITE_OK) {
// deal with error...
NSLog(@" -- ERROR!");
}
你能再详细一点吗? – Teo
@Theo。查看代码示例。 – Rob
我相信虽然断言是错误的,并且它会在复制成功时使应用程序崩溃。 – Teo