问题描述
在 where 子句中，如果第一个条件为 FALSE，那么在 SQL Server 中检查第二个条件?
In a where clause, if the first condition is FALSE, then the second condition is checked in SQL Server?
例如
select *
from users
where (condition 1) AND (condition 2)
如果条件 1 为 False，是否会检查条件 2?
If condition 1 is False, will condition 2 be checked?
推荐答案
它是不确定的.您不能依赖评估顺序.
It is non-deterministic. You cannot rely on order of evaluation.
SQL Server 查询优化器负责解析 T-SQL 查询并根据表大小、索引等创建执行计划.因此，针对相同数据库架构的相同 T-SQL 语句可能会根据数据库内容、配置等执行不同的操作.
SQL Server query optimizer is responsible for parsing T-SQL query and creating execution plan based on table sizes, indexes, etc. So same T-SQL statement against same database schema might be executed differently depending on database content, configuration, etc.
查询优化器优先考虑执行速度，并能够并行执行单个 T-SQL 语句.过滤子句的执行最终一个接一个执行的可能性很小.
Query optimizer prioritizes speed of execution and is able to parallelise execution of a single T-SQL statement. It is highly unlikely that execution of filter clauses ends up being executed one after another.
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