iOS数据库追加字段方法例子

-(void) addColoumOfUserNameWithModel:(id)model{    NSString *tableName = NSStringFromClass([model class]);    [self alertDataWithTableName:tableName addColumn:@{@"userName":@"text"}.mutableCopy];    }    -(NSInteger)alertDataWithTableName:(NSString *)tableName addColumn:(NSMutableDictionary *)dicColumn{        [self openDataBase];if ([self.DB open])    {        NSMutableString *paraStr = [[NSMutableString alloc] initWithString:[NSString stringWithFormat:@"alter table '%@'",tableName]];if (dicColumn.count)          [dicColumn.allKeys enumerateObjectsUsingBlock:^(NSString * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {    if(![self.DB columnExists:obj inTableWithName:tableName]) {                    [paraStr appendFormat:@"add column '%@' '%@' default '0',", obj, dicColumn[obj]];            }        }];if ([paraStr containsString:@"add column"]) {   [paraStr replaceCharactersInRange:NSMakeRange(paraStr.length - 1, 1) withString:@";"];    }else{  [self.DB close];            return -1;    }        BOOL res = [self.DB executeUpdate:paraStr];          [self.DB close];        if (res)        return 1;            else        return 0;} else    return -1;}