在PostgreSQL中对AND和OR条件进行分组 [英] Grouping AND and OR conditionals in PostgreSQL

问题描述

我总是在SQL查询中使用方括号.但是我有一个例子:

I always use brackets in sql queries. But I have example:

DELETE FROM prog 
WHERE prog_start >= $1 AND prog_start < $2
   OR prog_end > $1 AND prog_end <= $2

等于:

DELETE FROM prog
WHERE ( prog_start >= $1 AND prog_start < $2 )
   OR ( prog_end > $1 AND prog_end <= $2 ) 

还是不?

推荐答案

在SQL中，AND运算符比OR运算符具有优先级". PostgreSQL遵守这里的规范.您可以在docs 词汇中确定PostgreSQL中的确切优先级.结构:运算符优先级.

In SQL the AND operator takes "precedence" over OR operator. PostgreSQL adheres to the spec here. You can the exact precedence in PostgreSQL in the docs Lexical Structure: Operator Precedence.

因此，在您的情况下，结果将是相同的.但是，简单地使用括号会更容易，更清洁.

So in your case, the result will be the same. However, it's much easier, and cleaner to simply use the parentheses.

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