There are four database isolation levels, namely: 1. "Read Uncommitted" uncommitted read; 2. "Read Committed" committed read; 3. "Repeated Read" repeatable read; 4. "Serializable" Serial read.
The operating environment of this article: Windows 7 system, Dell G3 computer, mysql8 version.
There are four database isolation levels, as follows:
1. Uncommitted read (Read Uncommitted): allows dirty reads, that is, possible reads Get data modified by uncommitted transactions in other sessions
2. Read Committed: Only committed data can be read. Most databases such as Oracle default to this level (no repeated reads)
3. Repeated Read: Repeatable Read. Queries within the same transaction are consistent at the start of the transaction, InnoDB default level. In the SQL standard, this isolation level eliminates non-repeatable reads, but phantom reads still exist, but innoDB solves phantom reads
4. Serializable: Completely serialized reads, each time Both reading and writing need to obtain table-level shared locks, and reading and writing will block each other
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