Card transaction system and method on on-line and /or off-line

A method of processing a card transaction, comprising the steps of:

• (a) checking the balance of a card account, which is used for settling payment for transactions using a card;
• (b) generating a positive flag indicating that the card can be used when the balance of the card account is at least a negative amount which is set to a predetermined amount of money;
• (c) when the balance of the card account is larger than the negative amount and is less than a yellow amount, which is set to be larger than the negative amount, attempting to transfer money from an account of an owner of the card to the card account so that the balance of the card account is at least the yellow amount;
• and
• (d) when receiving information about the details of a card transaction, adjusting the charge for the card transaction from the balance of the card account and then repeating the steps starting from step (b) to update flag information corresponding to the card.

The method of maintaining data coherency between a server and a terminal, each of the server and the terminal including a fixed table, in which a memory area is divided into blocks, flag information corresponding to individual card numbers is sequentially stored in each block according to the card numbers, and version information indicating the data update history of each block is stored;

• and a variable table, which stores data regarding card numbers, for which flag information is changed, when there are changes in data regarding flag information stored in the fixed table, and version information indicating the data update history of the variable table, the method comprising:
• comparing the version information of each block of a fixed table included in the terminal with the version information of each block of a fixed table included in the server;
• when the version information of a certain block is not the same, updating data of the corresponding block of the fixed table in the terminal with data of the corresponding block of the fixed table in the server;
• comparing the version information of a variable table included in the terminal with the version information of a variable table included in the server;
• and
• when the version information is not the same, updating data stored in the variable table of the terminal with data stored in the variable table of the server.

A method of determining whether a card can be used, comprising:

• providing a fixed table, in which a memory area is divided into blocks, and flag information corresponding to individual card numbers is stored, and a variable table, which stores data regarding card numbers, for which flag information is changed, when there are changes in data regarding flag information stored in the fixed table;
• when there is a request to use a card, reading a card number from the card;
• checking whether the variable table includes data regarding the card number;
• if the variable table includes data regarding the card number, determining whether the card can be used according to flag information, which is stored in the variable table corresponding to the card number, and if the variable table does not include data regarding the card number, checking data in the fixed table;
• and
• reading flag information corresponding to the card number from the fixed table and determining whether the card can be used according to the read flag information.

A card terminal comprising:

• a fixed table database which stores flag information, which indicates whether each card can be used, corresponding to each card number;
• a variable table database which stores data regarding card numbers, for which flag information is changed, when there are changes in data regarding flag information stored in the fixed table database;
• a card reader which reads a card number from a given card when there is a request to use the card;
• and
• a card controller which checks whether the variable table database includes data regarding the card number of a given card, determining whether the card can be used according to flag information in the variable table database when the variable table database includes the data, and checking data in the fixed table database to read flag information corresponding to the card number from the fixed table database to determine whether the card can be used according to the read flag information when the variable table database does not include the data regarding the card number.

A data table for both on-line and off-line card transactions, comprising:

• a fixed table in which a memory area is divided into blocks, flag information corresponding to individual card numbers is sequentially stored in each block according to the card numbers, and version information indicating the data update history of each block is stored;
• and
• a variable table which stores data regarding card numbers, for which flag information is changed, when there are changes in data regarding flag information stored in the fixed table, and version information indicating the data update history of the variable table,
• wherein data stored in the fixed and variable tables is updated based on the version information of ach block in the fixed table and the version information of the variable table, and the data stored in the fixed table is updated in units of blocks based on the data stored in the variable table.