sqlite错误数据库被锁定 [英] sqlite error database is locked

问题描述

我在我写的iPhone应用程序中有一个sqlite数据库。我得到一个错误与下面的代码，我在后台线程中运行。在后台线程中，我调用此方法：

I am have a sqlite database in the iPhone application I am writing. I get an error with following code that I am running in a background thread. In the background thread, I call this method:

 - (BOOL) songIsInDatabase:(NSString *)songTitle
{
NSString *docsDir;
NSArray *dirPaths;

dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
docsDir = [dirPaths objectAtIndex:0];


//Build the path to the database file
NSString *databasePath = [[NSString alloc] initWithString:[docsDir stringByAppendingPathComponent:@"Database.db"]];

const char *dbpath = [databasePath UTF8String];

sqlite3_stmt *statement;

if(sqlite3_open(dbpath, &DB) == SQLITE_OK){

    NSString *insertSQL = [NSString stringWithFormat:@"select * from Bpm_Table where song_title = '%@'", songTitle];

    const char *insert_stmt = [insertSQL UTF8String];
    if(sqlite3_prepare_v2(DB, insert_stmt, -1, &statement, NULL) == SQLITE_OK)
    {
        while (sqlite3_step(statement) == SQLITE_ROW)
        {
            return YES;
            break;
        }
    }else{
        NSLog(@"the error is %s", sqlite3_errmsg(DB));
    }
    sqlite3_finalize(statement); 
}

[databasePath release];
return NO;
}

然后我调用这个方法：

- (void) addSongToDatabase: (NSString *) songTitle andBPM: (int)bpm andGenre: (NSString *) genre
{
NSString *docsDir;
NSArray *dirPaths;

dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
docsDir = [dirPaths objectAtIndex:0];


//Build the path to the database file
NSString *databasePath = [[NSString alloc] initWithString:[docsDir stringByAppendingPathComponent:@"Database.db"]];

const char *dbpath = [databasePath UTF8String];

sqlite3_stmt *statement;

if(sqlite3_open(dbpath, &DB) == SQLITE_OK){

    NSString *insertSQL = [NSString stringWithFormat:@"insert or replace into Bpm_Table (song_title, bpm, genre) values (\"%@\", \"%d\", \"%@\")", songTitle, bpm, genre];

    const char *insert_stmt = [insertSQL UTF8String];
    if(sqlite3_prepare(DB, insert_stmt, -1, &statement, NULL) == SQLITE_OK){
        if(sqlite3_step(statement) == SQLITE_DONE)
        {

        } else {
            NSLog(@"error: %s", sqlite3_errmsg(DB));
        }
    }sqlite3_finalize(statement);
}

[databasePath release];
}

如果我运行这两种方法，表示数据库已锁定的错误。我添加了 sqlite3_finalize 语句后poking google，希望能解决这个问题。如果我注释掉任何一种方法，我没有得到这个错误。

If I run both these methods, one right after the other, I get an error that says database is locked. I added the sqlite3_finalize statements after poking around google in hopes that would fix the issue. If I comment out either of the methods, I don't get this error.

有人知道发生了什么问题吗？

Does anyone know what's wrong?

推荐答案

sqlite数据库使用后...所以添加这行 sqlite3_close（DB）; 刚刚之后的sqlite3_finalize（语句）;

you must always close the sqlite database after using it ... so add this line sqlite3_close(DB); just after sqlite3_finalize(statement);

更新 -

您在一个while循环中返回YES -

You are returning YES in one of your while loop -

        while (sqlite3_step(statement) == SQLITE_ROW)
        {
            return YES;
            break;
        }

所以这里你要完成或关闭数据库。如果你每次打开它

so here you are nither finalizing nor closing the database.. you need to close if everytime you open it

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