PHP share 13: MySQL Things

Dirty Reads (Dirty read)

dirty reads mean that one transaction reads uncommitted data from another transaction, and this data is likely to be rolled back

Non-repeatable read (unrepeatable read)

Non-repeatable reading means that in database access, two identical queries within a transaction range return different data. This is caused by the commit of the other transaction modifications in the system during the query.

For example: Transaction B executes two times for a query, and when the first execution finishes, transaction a modifies its data. Data changes when querying again in transaction B

Phantom Read (Phantom Read)

Phantom reading is a phenomenon that occurs when a transaction is not executed independently, such as when the first transaction modifies data in a table, which involves all rows of data in the table. At the same time, the second transaction modifies the data in the table by inserting a new row of data into the table. Then the user who will be working on the first transaction in the future finds that there are no modified rows of data in the table, as if the illusion had occurred.

PHP share 13: MySQL Things