select会被DML干扰吗
当使用干净读取（读取已提交）时...选择查询是否会受到另一个 DML（插入、更新、删除）查询的干扰？如果是的话，能否提供一些案例。我正在使用 SQL Server 2005。
以下查询有可能产生不正确的数据。该查询不使用任何联接，它只是根据某些特定条件从单个表中获取数据。
Select PracticeCode, AccountNo, ProcCd, Modifier , ChargeDos, Paid as Amt, CreatedDate,
case When Paid > 0 then 'P'
When Paid = 0 and WrittenOff = DueAmt then 'A'
Else 'O'
End as Status
From Trn_Postings
Where CreatedDate between @StartDateTime and @EndDateTime
and ManualOverride not in ('F','S','X','G','O')
When using clean read (Read committed)... Will a select query be interfered by another DML (Insert, Update, Delete) query ? If yes, can you provide some cases. I'm using SQL Server 2005.
What is the possiblity the below query will be yield incorrect data. The query does not use any joins, it just fetches data from a single table based on some creteria.
Select PracticeCode, AccountNo, ProcCd, Modifier , ChargeDos, Paid as Amt, CreatedDate,
case When Paid > 0 then 'P'
When Paid = 0 and WrittenOff = DueAmt then 'A'
Else 'O'
End as Status
From Trn_Postings
Where CreatedDate between @StartDateTime and @EndDateTime
and ManualOverride not in ('F','S','X','G','O')
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读已提交隔离级别使用行级别的共享锁来避免读取脏数据。但是，由于锁定是在行级别，因此在事务完成之前其他行可能会发生更改，从而导致不可重复读取或幻像数据。
请参阅有关 设置事务隔离级别 了解更多详细信息和此博客文章就是一个很好的例子。
Read committed isolation level uses shared locks at the row level to avoid reading dirty data. However, since the locking is at the row level, other rows may change before the transaction completes, resulting in nonrepeatable reads or phantom data.
See the Microsoft documentation on SET TRANSACTION ISOLATION LEVEL for additional details and this blog post for a good example.