我正在创建一个使用sqlite数据库的iPhone应用程序。我的数据库中有一个表。最初我的表中没有行。我希望通过我的iPhone模拟器插入新记录时，该记录应自动更新到我的数据库。怎么可能这样呢？请有人帮我解决这个问题。
+ (void) getInitialDataToDisplay:(NSString *)dbPath
{
SQLAppDelegate *appDelegate = (SQLAppDelegate *)[[UIApplication sharedApplication] delegate];
if (sqlite3_open([dbPath UTF8String], &database) == SQLITE_OK) {
const char *sql = "select coffeeID, coffeeName from coffee";
sqlite3_stmt *selectstmt;
if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) {
while(sqlite3_step(selectstmt) == SQLITE_ROW) {
NSInteger primaryKey = sqlite3_column_int(selectstmt, 0);
Coffee *coffeeObj = [[Coffee alloc] initWithPrimaryKey:primaryKey];
coffeeObj.coffeeName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 1)];
coffeeObj.isDirty = NO;
[appDelegate.coffeeArray addObject:coffeeObj];
[coffeeObj release];
}
}
}
else
sqlite3_close(database); //Even though the open call failed, close the database connection to release all the memory.
}
+ (void) finalizeStatements
{
if (database) sqlite3_close(database);
if (deleteStmt) sqlite3_finalize(deleteStmt);
if (addStmt) sqlite3_finalize(addStmt);
if (detailStmt) sqlite3_finalize(detailStmt);
if (updateStmt) sqlite3_finalize(updateStmt);
}
- (id) initWithPrimaryKey:(NSInteger) pk
{
[super init];
coffeeID = pk;
coffeeImage = [[UIImage alloc] init];
isDetailViewHydrated = NO;
return self;
}
- (void) deleteCoffee
{
if(deleteStmt == nil) {
const char *sql = "delete from Coffee where coffeeID = ?";
if(sqlite3_prepare_v2(database, sql, -1, &deleteStmt, NULL) != SQLITE_OK)
NSAssert1(0, @"Error while creating delete statement. '%s'", sqlite3_errmsg(database));
}
//When binding parameters, index starts from 1 and not zero.
sqlite3_bind_int(deleteStmt, 1, coffeeID);
if (SQLITE_DONE != sqlite3_step(deleteStmt))
NSAssert1(0, @"Error while deleting. '%s'", sqlite3_errmsg(database));
sqlite3_reset(deleteStmt);
}
- (void) addCoffee
{
if(addStmt == nil) {
const char *sql = "insert into Coffee(CoffeeName, Price) Values(?, ?)";
if(sqlite3_prepare_v2(database, sql, -1, &addStmt, NULL) != SQLITE_OK)
NSAssert1(0, @"Error while creating add statement. '%s'", sqlite3_errmsg(database));
}
sqlite3_bind_text(addStmt, 1, [coffeeName UTF8String], -1, SQLITE_TRANSIENT);
sqlite3_bind_double(addStmt, 2, [price doubleValue]);
if(SQLITE_DONE != sqlite3_step(addStmt))
NSAssert1(0, @"Error while inserting data. '%s'", sqlite3_errmsg(database));
else
//SQLite provides a method to get the last primary key inserted by using sqlite3_last_insert_rowid
coffeeID = sqlite3_last_insert_rowid(database);
//Reset the add statement.
sqlite3_reset(addStmt);
}
- (void) hydrateDetailViewData
{
//If the detail view is hydrated then do not get it from the database.
if(isDetailViewHydrated) return;
if(detailStmt == nil) {
const char *sql = "Select price, CoffeeImage from Coffee Where CoffeeID = ?";
if(sqlite3_prepare_v2(database, sql, -1, &detailStmt, NULL) != SQLITE_OK)
NSAssert1(0, @"Error while creating detail view statement. '%s'", sqlite3_errmsg(database));
}
sqlite3_bind_int(detailStmt, 1, coffeeID);
if(SQLITE_DONE != sqlite3_step(detailStmt)) {
//Get the price in a temporary variable.
NSDecimalNumber *priceDN = [[NSDecimalNumber alloc] initWithDouble:sqlite3_column_double(detailStmt, 0)];
//Assign the price. The price value will be copied, since the property is declared with "copy" attribute.
self.price = priceDN;
NSData *data = [[NSData alloc] initWithBytes:sqlite3_column_blob(detailStmt, 1) length:sqlite3_column_bytes(detailStmt, 1)];
if(data == nil)
NSLog(@"No image found.");
else
self.coffeeImage = [UIImage imageWithData:data];
//Release the temporary variable. Since we created it using alloc, we have own it.
[priceDN release];
}
else
NSAssert1(0, @"Error while getting the price of coffee. '%s'", sqlite3_errmsg(database));
//Reset the detail statement.
sqlite3_reset(detailStmt);
//Set isDetailViewHydrated as YES, so we do not get it again from the database.
isDetailViewHydrated = YES;
}
- (void) saveAllData
{
if(isDirty)
{
if(updateStmt == nil)
{
const char *sql = "update Coffee Set CoffeeName = ?, Price = ?, CoffeeImage = ? Where CoffeeID = ?";
if(sqlite3_prepare_v2(database, sql, -1, &updateStmt, NULL) != SQLITE_OK)
NSAssert1(0, @"Error while creating update statement. '%s'", sqlite3_errmsg(database));
}
sqlite3_bind_text(updateStmt, 1, [coffeeName UTF8String], -1, SQLITE_TRANSIENT);
sqlite3_bind_double(updateStmt, 2, [price doubleValue]);
NSData *imgData = UIImagePNGRepresentation(self.coffeeImage);
int returnValue = -1;
if(self.coffeeImage != nil)
returnValue = sqlite3_bind_blob(updateStmt, 3, [imgData bytes], [imgData length], NULL);
else
returnValue = sqlite3_bind_blob(updateStmt, 3, nil, -1, NULL);
sqlite3_bind_int(updateStmt, 4, coffeeID);
if(returnValue != SQLITE_OK)
NSLog(@"Not OK!!!");
if(SQLITE_DONE != sqlite3_step(updateStmt))
NSAssert1(0, @"Error while updating. '%s'", sqlite3_errmsg(database));
sqlite3_reset(updateStmt);
isDirty = NO;
}
//Reclaim all memory here.
[coffeeName release];
coffeeName = nil;
[price release];
price = nil;
isDetailViewHydrated = NO;
}
- (void)setCoffeeName:(NSString *)newValue
{
self.isDirty = YES;
[coffeeName release];
coffeeName = [newValue copy];
}
- (void)setPrice:(NSDecimalNumber *)newNumber
{
self.isDirty = YES;
[price release];
price = [newNumber copy];
}
- (void)setCoffeeImage:(UIImage *)theCoffeeImage
{
self.isDirty = YES;
[coffeeImage release];
coffeeImage = [theCoffeeImage retain];
}
答案 0 :(得分：0)
好吧，因为我看到你有这个功能+(void) finalizeStatements;，你关闭你的数据库并完成准备好的查询。
首先，你不要从任何地方调用这个函数。无论如何，如果你以某种方式调用此函数，代码来自不正确，因为你应该首先完成所有语句，然后才关闭连接。
阅读 sqlite3_close 和 sqlite3_finalize 的文档。文档中有关 sqlite3_close 的内容：
应用程序必须[sqlite3_finalize |完成所有[准备好的陈述]和[sqlite3_blob_close |关闭]在尝试关闭对象之前，与[sqlite3]对象关联的所有[BLOB句柄]。
如果这对您没有帮助，请尝试在您准备的每个方法结束时完成语句。
希望这会对你有所帮助。
答案 1 :(得分：0)
当您尝试添加addCoffee时，我不确定您在getInitialDataToDisplay中打开的数据库变量是否仍然可用。为什么不关闭该连接，并在addCoffee开头打开一个新连接（并在完成时关闭它）