The ANSI/ISO standard SQL 92 refers to three different read phenomena when Transaction 1 reads data that Transaction 2 might have changed.
In the following examples, two transactions take place. In the first, Query 1 is performed. Then, in the second transaction, Query 2 is performed and committed. Finally, in the first transaction, Query 1 is performed again.
The queries use the following data table:
| id | name | age |
|---|---|---|
| 1 | Joe | 20 |
| 2 | Jill | 25 |
Read more about this topic: Isolation (database Systems)
Famous quotes containing the words read and/or phenomena:
“Tell my son how anxious I am that he may read and learn his Book, that he may become the possessor of those things that a grateful country has bestowed upon his papa—Tell him that his happiness through life depends upon his procuring an education now; and with it, to imbibe proper moral habits that can entitle him to the possession of them.”
—Andrew Jackson (1767–1845)
“The manifestation of poetry in external life is formal perfection. True sentiment grows within, and art must represent internal phenomena externally.”
—Franz Grillparzer (1791–1872)