A method of storing data in a database, the database defining a table and the data comprising at least one record. Each record comprises values for at least one field. The method comprises storing a plurality of schemas, each schema defining a respective set of fields associated with said table, wherein each of said records is associated with identification data identifying one of said schemas.
CLAIMS 1 . A method of storing data in a database, the database defining a table of data relations and the data comprising a plurality of records, each record comprising a data value for at least one field according to data relations of said table, the method comprising: storing a plurality of schemas, each schema defining a respective set of fields of data associated with said table; and associating each of said records with identification data identifying one of said schemas. 2. A method according to claim 1 , wherein each of said schemas has an associated schema identifier, and said identification data comprises a schema identifier. 3. A method according to any preceding claim, wherein said plurality of schemas are stored in a data dictionary of said database. 4. A method according to any preceding claim, further comprising: creating a further schema defining a further set of fields of data associated with said table; and storing said further schema. 5. A method according to any preceding claim, further comprising: reading one of said records; and modifying identification data associated with said read record to identify another of said plurality of schemas. 6. A method according to any preceding claim, wherein a plurality of records have common associated identification data. 7. A method according to claim 6, wherein said plurality records are stored in one or more pages, and wherein associating each of said records with identification data identifying one of said schemas comprises: associating identification data with each page; and storing in each page on ly records associated with one of said schemas identified by the identification data associated with that page. 8. A method according to claim 7, further comprising: reading a first record from a first page of records, said first page of records being associated with identification data identifying a first schema; receiving update data to be used to update said first record; and storing a second record in a second page of records, said second record being based upon said first record and said update data and said second page being associated with identification data identifying a second schema. 9. A method according to any one of claims 1 to 4 wherein associating each record with identification data identifying one of said schemas comprises storing in each record the respective identification data. 10. A method according to claim 9, further comprising: reading a record, said record being associated with identification data identifying a first schema; receiving update data to be used to update said record; and u pdating the said record based u pon said u pdate data and mod ifying identification data stored on said record to identify a second schema. 1 1 . A method according to any preceding claim, wherein a first schema of said plurality of schemas comprises a first plurality of fields of data and a second schema of said plurality of schemas comprises a second plurality of fields of data, said second plurality of fields including said first plurality of fields and at least one further field of data. 12. A method according to claim 1 1 wherein said at least one further field of said second schema is associated with at least one default value. 13. A method of reading a record from a database, the database defining a table and the data comprising a plurality of records, each record comprising values for at least one field, the database storing a plurality of schemas, each schema defining a respective set of fields associated with said table, the method comprising: reading identification data associated with said record to identify one of said schemas; and reading said at least one record based upon said identified schema. 14. A computer readable medium carrying computer readable instructions configured to carry out a method according to any preceding claim. 15. Computer apparatus for storing data, the apparatus comprising: a memory storing processor readable instructions; and a processor configured to read and execute instruction stored in said memory; wherein said processor readable instructions comprise instructions controlling the processor to carry out a method according to any one of claims 1 to 13.