{"id":48952,"date":"2017-08-04T11:00:42","date_gmt":"2017-08-04T08:00:42","guid":{"rendered":"http:\/\/examples.javacodegeeks.com\/?p=48952"},"modified":"2019-03-05T13:02:43","modified_gmt":"2019-03-05T11:02:43","slug":"jdbc-nested-transactions-example","status":"publish","type":"post","link":"https:\/\/examples.javacodegeeks.com\/java-development\/core-java\/sql\/jdbc-nested-transactions-example\/","title":{"rendered":"JDBC Nested Transactions Example"},"content":{"rendered":"

A nested transaction<\/strong> is used to provide a transactional guarantee for a subset of operations performed within the scope of a larger transaction. Doing this allows us to commit and abort the subset of operations independently of the larger transaction.<\/p>\n

This operation is theoretically possible, however, in JDBC 3.0 we can\u2019t achieve this as easily as the definition looks. In JDBC, programmers can achieve this effect using savepoints<\/strong>.
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1. Introduction<\/h2>\n

In this JDBC Nested Transactions example, we will see how to achieve this phenomenon by using the JDBC Savepoints<\/em>.<\/p>\n

1.1 Why JDBC Transactions?<\/h3>\n

In the database systems, Transaction<\/strong> is a set of actions to be carried out as a single or an atomic action. Either all of the actions are carried out, or none of them.<\/p>\n

The classic example of when transactions are necessary is the example of bank accounts<\/span>. Let\u2019s say you need to transfer $100 from one account to the other. You do so by subtracting $100 from the first account, and adding $100 to the second account. If this process fails after you have subtracted the $100 from the first bank account, the $100 are never added to the second bank account and hence the money is lost in the cyber space.<\/p>\n

To solve this problem, the subtraction and addition of the $100 are grouped into a transaction<\/em>. If the subtraction succeeds, but the addition fails, you can roll-back the first subtraction. That way the database is left in the same state as before the subtraction was executed.<\/p>\n

1.2 What are JDBC Transactions?<\/h3>\n

A transaction<\/strong> is a group of operation used to perform a single task; if all operations in the group are a success then the task is finished and the transaction is successfully completed. But if anyone operation in the group is failed, then the task is failed and the transaction is failed.<\/p>\n

\"Fig.<\/a>
Fig. 1: Java Database Connectivity (JDBC) Transactions<\/figcaption><\/figure><\/p>\n

Let\u2019s consider a movie ticket booking is a transaction. This task contains 4 operations:<\/p>\n

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  1. Choose the seats.<\/li>\n
  2. Reserve the seats.<\/li>\n
  3. Payment.<\/li>\n
  4. Issue the movie tickets.<\/li>\n<\/ol>\n

    If all the above 4 operations are done successfully then a transaction is finished<\/em> successfully. But if any one operation is failed in the middle then all operations are canceled and the transaction is failed<\/em>.<\/p>\n

    1.3 Properties of Transaction Management<\/h3>\n

    Every JDBC Transaction follows some transaction properties and these are called as ACID<\/strong> properties. ACID stands for Atomicity<\/em>, Consistency<\/em>, Isolation<\/em>, and Durability<\/em>.<\/p>\n

    \"Fig.<\/a>
    Fig. 2: JDBC Transaction Management Properties<\/figcaption><\/figure><\/p>\n