01. How SQL Server reads and writes data

1. Data read/write process as a relational database, SQL Server naturally maintains the ACID feature of transactions, and the read/write conflicts of databases are controlled at the transaction isolation level. No matter whether the transaction is enabled or not, the transaction exists. Flowchart: data read/write flowchart 0. Transaction start (1) All DML statements must be based on transactions.

I. Brief data read/write process as a relational database, SQL Server naturally maintains the ACID feature of transactions, and the read/write conflicts of databases are controlled at the transaction isolation level. No matter whether the transaction is enabled or not, the transaction exists. Flowchart: data read/write flowchart 0. Transaction start (1) All DML statements must be based on transactions.

1. Brief data read/write process
As a relational database, SQL Server naturally maintains the ACID feature of transactions. The Hong Kong Server is rented and the read/write conflicts of databases are controlled at the transaction isolation level. No matter whether the transaction is enabled or not, the transaction exists. The flowchart is as follows:

Data read/write Flowchart

0. Start transaction
(1) All DML statements must be transaction-based. In the U.S. space, if the transaction is not explicitly enabled, the Hong Kong server manually writes begin tran, SQL Server regards each statement as a transaction and automatically submits the transaction.

That is to say, SQL SERVER does not enable implicit transactions by default. This is the opposite of ORACLE. ORACLE enables implicit transactions by default. Each DML statement or statement block must be manually committed.

To change the default behavior in SQL Server, you can make the following settings in the session. If no implicit transaction is opened, SQL Server automatically submits the current DML statement, manual COMMIT is required for submission.

IMPLICIT_TRANSACTIONS TEST_TRAN (id int) insert into TEST_TRAN VALUES (1) OPENTRAN ()