在iphone上删除数据sqllite - 数据库已锁定

Question

my app crashed when I try to delete a data from my SqlLite db.

This is the error: Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Error while deleting. 'database is locked' Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Error while deleting. 'database is locked'

This is all my code on database:

#import "Database.h"

static sqlite3 *database = nil;
static sqlite3_stmt *deleteStmt = nil;
static sqlite3_stmt *addStmt = nil;

@implementation Database

@synthesize id_poi, pathDb, arrPoi;

- (id) initWithData:(NSDictionary *) data {

    [super init];
    NSLog(@"%@",[data objectForKey:@"pathDb"]);
    NSLog(@"id_poi = %@",[data objectForKey:@"id_poi"]);
    //setto l'id nello stato dell'oggetto
    id_poi = [data objectForKey:@"id_poi"];
    pathDb = [data objectForKey:@"pathDb"];

    return self;
}

- (void) deletePoi {

    if (sqlite3_open([pathDb UTF8String], &database) == SQLITE_OK) {
        const char *sql = "delete from Poi where id_poi = ?";
        sqlite3_stmt *deleteStmt;
        if(sqlite3_prepare_v2(database, sql, -1, &deleteStmt, NULL) == SQLITE_OK) {
            //When binding parameters, index starts from 1 and not zero.
            sqlite3_bind_int(deleteStmt, 1, [id_poi integerValue]);

            if (SQLITE_DONE != sqlite3_step(deleteStmt)) {
                NSAssert1(0, @"Error while deleting. '%s'", sqlite3_errmsg(database));
                [[WPActivityIndicator sharedActivityIndicator] hide];
                return;
            }
        } else {
            NSAssert1(0, @"Error while creating delete statement. '%s'", sqlite3_errmsg(database));   
        }
        sqlite3_finalize(deleteStmt);
    } else {
        sqlite3_close(database); //Even though the open call failed, close the database connection to release all the memory.
    }


    [[WPActivityIndicator sharedActivityIndicator] hide];
}

- (BOOL) checkIdPoi {

    // lista temporanea
    NSMutableArray *listaTemp = [[NSMutableArray alloc] init];
    // Oggetto che contiene i vari elementi
    NSMutableDictionary *dictionary;

    NSMutableString *str_id_poi;//id della persona

    if (sqlite3_open([pathDb UTF8String], &database) == SQLITE_OK) {
        // query che ricava i valori
        const char *sql = "select id_poi from Poi where id_poi = ?";
        sqlite3_stmt *selectstmt;

        if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) {

            sqlite3_bind_int(selectstmt, 1 , [id_poi integerValue]);
            while(sqlite3_step(selectstmt) == SQLITE_ROW) {
                // ricaviamo i valori letti dalla query
                str_id_poi = [NSMutableString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 0)];

                // inseriamo tutti i valori letti in un unico oggetto
                dictionary = [[NSMutableDictionary alloc] initWithObjectsAndKeys:str_id_poi, @"id_poi", nil];
                //NSLog(@"str_id_poi = %@",str_id_poi);
                [listaTemp addObject:dictionary];
                [dictionary release];
                return TRUE;
            }
        } else {
            NSAssert1(0, @"Error while read data. '%s'", sqlite3_errmsg(database));
            return FALSE;
        }
    }
    else {
        sqlite3_close(database);
        return FALSE;
    }

    return FALSE;

}

- (void) addPoi {

    //NSLog(@"%@",pathDb);

    if (sqlite3_open([pathDb UTF8String], &database) == SQLITE_OK) {

        const char *sql = "insert into Poi(id_poi) Values(?)";
        sqlite3_stmt *addStmt;
        if(sqlite3_prepare_v2(database, sql, -1, &addStmt, NULL) == SQLITE_OK) {

            NSString *str_id_poi = [[NSString alloc] initWithFormat:@"%d", [id_poi integerValue]];
            sqlite3_bind_text(addStmt, 1, [str_id_poi UTF8String], -1, SQLITE_TRANSIENT);

            if(SQLITE_DONE != sqlite3_step(addStmt)) {
                NSAssert1(0, @"Error while inserting data. '%s'", sqlite3_errmsg(database));
                [[WPActivityIndicator sharedActivityIndicator] hide];
                return;
            } else {
                //SQLite provides a method to get the last primary key inserted by using sqlite3_last_insert_rowid
                //id_poi = sqlite3_last_insert_rowid(database);
            }

            //Reset the add statement.
            sqlite3_reset(addStmt);


        } else {
            NSAssert1(0, @"Error while creating add statement. '%s'", sqlite3_errmsg(database));            
        }
        sqlite3_finalize(addStmt); 

    } else {
        sqlite3_close(database); //Even though the open call failed, close the database connection to release all the memory.
    }

    sqlite3_close(database);

    [[WPActivityIndicator sharedActivityIndicator] hide];

}

// Carica i valori dal database passato come parametro
-(NSMutableArray*)getIdPOI {

    // lista temporanea
    NSMutableArray *listaTemp = [[NSMutableArray alloc] init];
    // Oggetto che contiene i vari elementi
    NSMutableDictionary *dictionary;

    NSMutableString *str_id_poi;//id della persona

    if (sqlite3_open([pathDb UTF8String], &database) == SQLITE_OK) {
        // query che ricava i valori
        const char *sql = "select id_poi from Poi";
        sqlite3_stmt *selectstmt;

        if(sqlite3_prepare_v2(database, sql, -1, &selectstmt, NULL) == SQLITE_OK) {

            while(sqlite3_step(selectstmt) == SQLITE_ROW) {
                // ricaviamo i valori letti dalla query
                str_id_poi = [NSMutableString stringWithUTF8String:(char *)sqlite3_column_text(selectstmt, 0)];

                // inseriamo tutti i valori letti in un unico oggetto
                dictionary = [[NSMutableDictionary alloc] initWithObjectsAndKeys:str_id_poi, @"id_poi", nil];
                //NSLog(@"str_id_poi = %@",str_id_poi);
                [listaTemp addObject:dictionary];
                [dictionary release];
            }

            //Reset the add statement.
            sqlite3_reset(selectstmt);

        } else {
            NSAssert1(0, @"Error while read data. '%s'", sqlite3_errmsg(database));
        }

        //ADD THIS LINE TO YOUR CODE
        sqlite3_finalize(selectstmt);
    }
    else
        sqlite3_close(database);

    sqlite3_close(database);

    return listaTemp;
}


+ (void) finalizeStatements {
    if(database) sqlite3_close(database);
    if(deleteStmt) sqlite3_finalize(deleteStmt);
    if(addStmt) sqlite3_finalize(addStmt);
}


-(void)dealloc {
    [pathDb release];
    [arrPoi release];

    [super dealloc];
}

@end

Any suggest?

Answer 1

This type of error can occur when more then one query is fired for sqlite db. When you are executing any query, you need to synchronize all calls to the database.

Wrap all your database code in a @synchronized block like so:

@synchronized(self)
{
   // database query code goes here
}

NB. this example assumes all database queries are executed from inside the 1 class. If not, you should replace 'self' with a common object instance that is shared by all classes that interface with the database. Alternatively, you can run all database statements on the main thread.

Answer 2

This usually happens when the database was opened and then not closed properly. It could be because you have the same instance of database opened from somewhere else.(Like a different class or SQLite manager).

It is usually advisable to create a singleton instance which communicates with your database rather opening and closing the database again and again.. hoping this helps.