预编译方面的声明与准备好的声明

问题描述

我了解使用Statement和PreparedStatement之间的主要区别(PreparedStatements允许传入参数).但是我读到了两者之间的细微差别-即PreparedStatement比通用语句要快，因为PreparedStatement SQL是预编译的.

I understand the main difference between using Statement and PreparedStatement (PreparedStatements allow passing in parameters). But I read about a subtle difference between the two - namely that PreparedStatements can be quicker than generic Statements, because PreparedStatement SQL is precompiled.

预编译到底是什么意思，为什么会有所作为?

What exactly does being precompiled mean, and why does it make a difference?

推荐答案

一条准备好的语句执行以下检查:

A prepared statement performs the following checks:

• 确保表和列存在
• 确保参数类型匹配其列
• 解析SQL以确保语法正确
• 编译并缓存已编译的SQL，因此无需重复这些步骤即可重新执行它

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