插入或更新时，数据库在iOS中的SQLite中被锁定错误？
我有一个CITIES表，其中存储了相同的城市名称和日期。现在，对于每个事务，如INSERT，UPDATE，都会第一次成功执行。但是，在第二次尝试时，我收到一个错误，说数据库已锁定错误。我在哪里错过了关闭和/或最终确定，我似乎不明白。造成这种混乱的原因是使用了嵌套查询，插入或更新时，数据库在iOS中的SQLite中被锁定错误？,ios,objective-c,sqlite,Ios,Objective C,Sqlite,我有一个CITIES表，其中存储了相同的城市名称和日期。现在，对于每个事务，如INSERT，UPDATE，都会第一次成功执行。但是，在第二次尝试时，我收到一个错误，说数据库已锁定错误。我在哪里错过了关闭和/或最终确定，我似乎不明白。造成这种混乱的原因是使用了嵌套查询，update/insert查询依赖于count查询的结果。代码流程如下所示 1] 读取数据库/重新查看数据已完成 2] 一旦数据以日期排序方式显示，就可以从表中选择新城市或现有城市 3] 这将调用“viewDataBaseForCi
update/insertcount //Retrieve data
-(NSMutableArray *)getCities{
const char *dbpath = [databasePath UTF8String];
@try {
if (sqlite3_open(dbpath, &citiesDB) == SQLITE_OK)
{
NSString *querySQL = [NSString stringWithFormat:@"SELECT cityname FROM CITIES ORDER BY modifieddate DESC"];
const char *query_stmt = [querySQL UTF8String];
NSMutableArray *resultArray = [[NSMutableArray alloc]init];
if (sqlite3_prepare_v2(citiesDB,
query_stmt, -1, &statement, NULL) == SQLITE_OK)
{
while (sqlite3_step(statement) == SQLITE_ROW)
{
NSString *name = [[NSString alloc] initWithUTF8String:
(const char *) sqlite3_column_text(statement, 0)];
[resultArray addObject:name];
}
sqlite3_reset(statement);
sqlite3_finalize(statement);
return resultArray;
}
}
}
@catch (NSException *exception) {
NSLog(@"SQL ERROR : %@",[exception reason]);
}
@finally {
sqlite3_close(citiesDB);
}
return nil;
}
//save our data
-(void)viewDataBaseForCity:(NSString *)cityName addedDate:(NSString *)dateAdded{
modifiedDate = dateAdded;
recentCity = cityName;
const char *dbpath = [databasePath UTF8String];
@try {
if (sqlite3_open(dbpath, &citiesDB)==SQLITE_OK)
{
NSString *querySQL = [NSString stringWithFormat:@"SELECT COUNT(CITYNAME) FROM CITIES WHERE CITYNAME ='%@'", cityName];
const char *query_stmt = [querySQL UTF8String];
if (sqlite3_prepare_v2(citiesDB, query_stmt, -1, &statement, NULL)!= SQLITE_OK)
{
NSAssert(0, @"Failed to open database");
NSLog(@"%s Prepare failure '%s' (%1d)", __FUNCTION__, sqlite3_errmsg(citiesDB), sqlite3_errcode(citiesDB));
}else{
if (sqlite3_step(statement)==SQLITE_ROW)
{
int count = sqlite3_column_int(statement, 0);
NSLog(@"Found city count is : %d",count);
if (count==0) {
//insert
[self insertNewCity];
}else{
//update
[self updateCities];
}
sqlite3_finalize(statement);
}else{
NSLog(@"Not Found");
}
}
}
}
@catch (NSException *exception) {
NSLog(@"SQlite exception : %@",[exception reason]);
}
@finally {
sqlite3_close(citiesDB);
}
}
//Insert
-(void)insertNewCity{
NSString *insert_sql = [NSString stringWithFormat:@"INSERT INTO CITIES(cityname,modifieddate)VALUES (\'%@\',\'%@\')",recentCity,modifiedDate];
const char *insert_stmt = [insert_sql UTF8String];
sqlite3_prepare_v2(citiesDB, insert_stmt, -1, &statement, NULL);
if (sqlite3_step(statement)==SQLITE_DONE)
{
NSLog(@"Insert Successfull");
NSLog(@"SQLite Entry for Cities: %s and Time : %s", sqlite3_column_text(statement, 0),sqlite3_column_text(statement, 1));
}
else{
NSLog(@"Insert Failed");
NSLog(@"%s Prepare failure '%s' (%1d)", __FUNCTION__, sqlite3_errmsg(citiesDB), sqlite3_errcode(citiesDB));
}
sqlite3_finalize(statement);
}
//Update
-(void)updateCities{
NSString *querySQL = [NSString stringWithFormat:@"UPDATE CITIES set modifieddate ='%@' WHERE cityname='%@'", modifiedDate, recentCity];
NSLog(@"Update Query : %@",querySQL);
const char *query_stmt = [querySQL UTF8String];
if (sqlite3_prepare_v2(citiesDB, query_stmt, -1, &statement, NULL) == SQLITE_OK)
{
if (sqlite3_step(statement)==SQLITE_DONE){
NSLog(@"updated successfully");
}else{
NSLog(@"%s Update failure '%s' (%1d)", __FUNCTION__, sqlite3_errmsg(citiesDB), sqlite3_errcode(citiesDB));
}
sqlite3_finalize(statement);
}
}
我解决了这个问题，首先进行计数，完成交易，然后决定是更新还是删除
-(void)viewDataBaseForCity:(NSString *)cityName addedDate:(NSString *)dateAdded{
int count =0;
modifiedDate = dateAdded;
recentCity = cityName;
const char *dbpath = [databasePath UTF8String];
@try {
if (sqlite3_open(dbpath, &citiesDB)==SQLITE_OK)
{
NSString *querySQL = [NSString stringWithFormat:@"SELECT COUNT(CITYNAME) FROM CITIES WHERE CITYNAME ='%@'", cityName];
const char *query_stmt = [querySQL UTF8String];
if (sqlite3_prepare_v2(citiesDB, query_stmt, -1, &statement, NULL)!= SQLITE_OK)
{
NSAssert(0, @"Failed to open database");
NSLog(@"%s Prepare failure '%s' (%1d)", __FUNCTION__, sqlite3_errmsg(citiesDB), sqlite3_errcode(citiesDB));
}else{
if (sqlite3_step(statement)==SQLITE_ROW)
{
count = sqlite3_column_int(statement, 0);
NSLog(@"Found city count is : %d",count);
}else{
NSLog(@"Not Found");
}
sqlite3_finalize(statement);
}
}
if (count==0) {
//insert
[self insertNewCity];
}else{
//update
[self updateCities];
}
}
@catch (NSException *exception) {
NSLog(@"SQlite exception : %@",[exception reason]);
}
@finally {
sqlite3_close(citiesDB);
}
}
你没有关闭数据库访问。我终于要关闭了。这还不够吗？因为在
viewDataBaseForCity