Isolation level isolation

Isolation level isolation (1) Data Reading phenomenon www.2cto. com1. dirty reading. Read uncommitted data. 2. Duplicate read is not allowed. In the same transaction, the same statement is read twice and the result is different. 3. Phantom read. In the same transaction, because of the addition of records in the database table, the same statement reads two different results. (2) Table locking

Isolation level of transactions isolation (1) Data Reading phenomenon www.2cto.com 1. Dirty reading. Read uncommitted data. 2. Duplicate read is not allowed. In the same transaction, the same statement is read twice and the result is different. 3. Phantom read. In the same transaction, because of the addition of records in the database table, the same statement reads two different results. (2) Table locking

Isolation level isolation

(1) Data Reading

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1. Dirty read. Read uncommitted data.

2. Duplicate read is not allowed. In the same transaction, the same statement is read twice and the result is different.

3. Phantom read. In the same transaction, because of the addition of records in the database table, the same statement reads two different results.

(2) Locking a table row

(3) transaction isolation level

1. Read uncommitted data. READ_UNCOMMITTED

Dirty reads may occur.

2. Read submitted data. READ_COMMITTED

Avoid dirty reading. But there will be non-repeated reads and Phantom reads.

3. Repeatable read. REPEATABLE_READ

Solved the problem of non-repeated reading.

4. serial port. SERIALIZABLE

Resolved phantom read.