Introduction-

A blockchain is a digital ledger of transactions protected from hacking and modification by a network of computers. With the help of technology, people can transact with one another securely without the need for a middleman like a bank, government, or another third party. Cryptography is used to link together blocks, a set of records. Peer-to-peer computer networks independently verify each transaction, time-stamp it, and then add it to the ledger. Data cannot be easily changed once it has been captured. Blockchain technology has gained popularity with the increasing use of Bitcoin, Ethereum, and other cryptocurrencies, but it also has promising uses in the legal sector, real estate transactions, the medical field, and any other sector that requires the authorization and documentation of a series of actions or transactions.

How Does Block chain Work?

The name “blockchain” is not by chance: The digital ledger is sometimes depicted as a “chain” made up of distinct data “blocks.” A new “block” is made and attached to the “chain” each time new data is added to the network on a regular basis. To achieve this, all nodes must update their copies of the blockchain ledger to match one another. Blockchains are also referred to as distributed ledger technologies.

Advantages of block chain:

Higher Accuracy of Transactions:

This can lower errors because a blockchain transaction needs to be confirmed by several nodes. The other nodes would notice something is off and recognise the error if one node has a database error. In contrast, if a mistake is made in a traditional database, it may be more likely to be accepted. Additionally, each asset is uniquely identifiable and recorded on the blockchain ledger, eliminating the possibility of double spending.

No Need for Intermediaries:

Blockchain enables two parties to a transaction to confirm and finish it directly between themselves. This saves time and money on paying a middleman, such as a bank. “It has the potential to promote financial empowerment for the unbanked or under-banked populations of the world, to increase the efficiency of all digital transactions, and to fuel a new generation of internet apps,”

Extra Security:

 Theoretically, it is nearly impossible to conduct fraudulent transactions on a decentralized network like blockchain. They would have to hack each node and modify each ledger in order to add fake transactions. While not strictly impossible, many cryptocurrency blockchain systems use proof-of-stake or proof-of-work transaction verification techniques, which make it challenging and not in the participants’ best interests to add fraudulent transactions.

More Efficient Transfers:

People may move assets and money more effectively because blockchains are available around-the-clock, especially when doing so overseas. There is no need for them to wait days for a bank or a government organization to manually authenticate everything.

Conclusion:

Blockchain innovation could be very reciprocal in a chance space for the future world that incorporates both unified and decentralized models. Like any new innovation, the blockchain is a thought that at first disturbs, and over the long run it could advance the improvement of a bigger environment that incorporates both the prior way and the new development.  Hence, after some time, blockchain innovation could exist in a bigger biological system with both unified and decentralized models.

Today, I came across one of my friends who was having the misconception of oracles in Blockchain as part of Oracle database. So, I thought of writing this small article to explain what exactly oracles in Blockchain are and how they are different from inbuilt blockchain tables in oracle database.
When we talk about oracles in Blockchain technology it means that oracles in blockchain are entities who connect blockchain with external system and as per the inputs and outputs smart contracts are executed. Smart contracts are deployed on blockchain, and they execute transactions which are transparent and irreversible.

Blockchain Tables in Oracle

When we talk about blockchain tables in oracle they are the tables where we can only append the data, or we can say we can only insert the data. We can also restrict the deletion of rows either by specifying the value as shown in the below example:
SQL> CREATE BLOCKCHAIN TABLE Tryblockchain (test1 VARCHAR2(128), t NUMBER)
    NO DROP UNTIL 1 DAYS IDLE
    NO DELETE UNTIL 16 DAYS AFTER INSERT
    HASHING USING “SHA2_512” VERSION “v1”;  
Table created.

Now, in the above create table command a blockchain table will be created with parameters “No Drop until 1 days idle” means that table can be dropped after one day of no insertion of rows in the table and if we want that table not to be dropped forever we will define “No drop”. Other parameter “No delete until 16 days after insert” means that each row in the table is protected from deletion as per the specified number of days and minimum value is 16. Next parameter “Hashing Using ‘SHA2 512’” specifies the encryption, chaining up rows, validate the data and making it temper resistant.
Oracle blockchain table helps in implementing the centralized ledger model where all the users have the access to the temper proof ledger.
Blockchain tables helps in creating a centralized ledger model by reducing the overhead costs of the project, saves time in comparison to the decentralised system.
Apart from the above features while creating centralized ledger system it is easier to maintain in house like taking the backup, archiving, providing the controlled access, faster access of data and output to the end user and no additional infrastructure is required except the already installed Oracle database. 

Blockchain is a shared, peer to peer, immutable distributed ledger in which all the transactions are cryptographically secure. Blockchain provides users a decentralized public network which is not controlled by a single user or entity. It makes the system robust and secure against any sort of tempering with the data. Block chain helps peer to peer transactions without any intervention of the third party. Blockchain consists of more than one block and each block can be also referred to a node and each transaction is validated by each node. The very first block is known as Genesis block followed by n number of blocks. A single block consists of data and hash value (Unique Signature) which is depicted in the below diagram.