Suppose I do the following set of SQL queries (pseudocode) in a table with only one column CITY:
假设我在一个只有一列CITY的表中执行以下一组SQL查询（伪代码）：
BEGIN TRANSACTION;
INSERT INTO MyTable VALUES( 'COOLCITY' );
SELECT * FROM MyTable WHERE ALL;
COMMIT TRANSACTION;
is the SELECT guaranteed to return COOLCITY?
SELECT保证返回COOLCITY？
1 个解决方案
#1
6
Yes.
是。
The INSERT operation would take an X lock out on at least the newly added row. This won't get released until the end of the transaction thus preventing a concurrent transaction from deleting or updating this row.
INSERT操作将至少对新添加的行进行X锁定。这将在事务结束之前释放，从而防止并发事务删除或更新此行。
A transaction is not blocked by its own locks so the SELECT would return COOLCITY.
事务不会被自己的锁阻塞，因此SELECT将返回COOLCITY。
#1
6
Yes.
是。
The INSERT operation would take an X lock out on at least the newly added row. This won't get released until the end of the transaction thus preventing a concurrent transaction from deleting or updating this row.
INSERT操作将至少对新添加的行进行X锁定。这将在事务结束之前释放，从而防止并发事务删除或更新此行。
A transaction is not blocked by its own locks so the SELECT would return COOLCITY.
事务不会被自己的锁阻塞，因此SELECT将返回COOLCITY。