What would be the best way to save arrays in SQLite?

Question

I'm trying to add an array into an SQLite Database on an iPhone. The thing is, I do not know how many array objects the user will want to use. It may be 1, it may be 10. If I allocated 10 fields in a SQLite Table, that would be 9 wastes if the user was to use one, and it would put an upper bound to 10 entries.

Thus I thought of using a single VARCHAR type field, and adding each object of the array with a special character between each objects. How would this be performance wise? Any better ideas?

Answer 1

My guess will be to use the NSCoder framework. As NSArray conforms to NSCoding protocol, the serialization is already done to you:

  NSMutableData *data = [[NSMutableData alloc] init];
  NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
  [archiver encodeObject:myArray forKey:myArchiveKey];
  [archiver finishEncoding];
  [archiver release];

  // write here data object to a BLOB field of your SQLite db

Decoding will be very similar

Answer 2

您可以将它们保存为OBJECT列。

Answer 3

您可以将数组条目存储为行。

Answer 4

您可以将数组保存为json对象格式，同时检索将json对象转换为数组。