Question

I have database, but when i tried to remove data from the database nothing happens, what should i do to make sure it works? Because when i pressed delete the dta is still in the database

This is the code:

/file path to database
    -(NSString*)filePath {
        NSArray*paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        return [[paths objectAtIndex:0]stringByAppendingPathComponent:@"bp.sql"];
    }

    //open database
    -(void)openDB {

        if(sqlite3_open([[self filePath]UTF8String], &db) !=SQLITE_OK) {
            sqlite3_close(db);
            NSAssert(0, @"Databese failed to open");
        }

        else {
            NSLog(@"database opemed");
        }


    }


    - (IBAction)del:(id)sender {

        NSString*sql = [NSString stringWithFormat:@"DELETE key, theDate, customer, code1, code2 FROM summary WHERE key=\"%@\"",customerName];
        const char* query_stmt = [sql UTF8String];
        sqlite3_stmt*statement;

        sqlite3_prepare_v2(db, query_stmt, -1, & statement, NULL);
        if (sqlite3_step(statement) == SQLITE_DONE)
        {
           NSAssert(0, @"database object delete failed");

        } else {
            NSLog(@"No error");

        }
        sqlite3_finalize(statement);
        sqlite3_close(db)

Answer 1

You can’t delete specific column values using the DELETE query. It’s for removing the entire row.

The problem is with the following query:

NSString*sql = [NSString stringWithFormat:@"DELETE key, theDate, customer, code1, code2 FROM summary WHERE key=\"%@\"",customerName];

Change it to:

NSString*sql = [NSString stringWithFormat:@"DELETE FROM summary WHERE key=\"%@\"",customerName];

If you need to remove particular column value of a row use the UPDATE query.

Please check the sqlite documentation for the details