除了在同一个session,可以看到自己没有提交的数据外，其他的session不可以看到没有提交的数据。 允许其他用户看到未提交的数据的隔离级别是READ UNCOMMITED. 但是oracle不支持这种隔离级别，SQLSERVER和DB2支持READ UNCOMMITED. 以下来自oracle:READ UNCOMMITTED. The READ UNCOMMITTED isolation level allows dirty reads. [del]Oracle Database doesn't use dirty reads, nor does it even allow them[/del]. The basic goal of a READ UNCOMMITTED isolation level is to provide a standards-based definition that allows for nonblocking reads. As you've seen, Oracle Database provides for nonblocking reads by default. You'd be hard-pressed to make a SELECT query block and wait in the database (as noted earlier, there is the special case of a distributed transaction). Every single query, be it a SELECT, INSERT, UPDATE, MERGE, or DELETE, executes in a read-consistent fashion. It might seem funny to refer to an UPDATE statement as a query, but it is. UPDATE statements have two components: a read component as defined by the WHERE clause, and a write component as defined by the SET clause. UPDATE statements read and write to the database, as do all DML statements. The case of a single row INSERT using the VALUES clause is the only exception to this, because such statements have no read component—just the write component.
允许其他用户看到未提交的数据的隔离级别是READ UNCOMMITED.
但是oracle不支持这种隔离级别，SQLSERVER和DB2支持READ UNCOMMITED.
以下来自oracle:READ UNCOMMITTED. The READ UNCOMMITTED isolation level allows dirty reads.
[del]Oracle Database doesn't use dirty reads, nor does it even allow them[/del]. The basic goal of a READ UNCOMMITTED isolation level is to provide a standards-based definition that allows for nonblocking reads. As you've seen, Oracle Database provides for nonblocking reads by default. You'd be hard-pressed to make a SELECT query block and wait in the database (as noted earlier, there is the special case of a distributed transaction). Every single query, be it a SELECT, INSERT, UPDATE, MERGE, or DELETE, executes in a read-consistent fashion. It might seem funny to refer to an UPDATE statement as a query, but it is. UPDATE statements have two components: a read component as defined by the WHERE clause, and a write component as defined by the SET clause. UPDATE statements read and write to the database, as do all DML statements. The case of a single row INSERT using the VALUES clause is the only exception to this, because such statements have no read component—just the write component.