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minor language changes to HQL doc

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Gavin King 2023-09-01 08:55:39 +02:00
parent 32f635e752
commit f9a0065976
1 changed files with 6 additions and 6 deletions
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documentation/src/main/asciidoc/querylanguage/Concepts.adoc
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@ -1,7 +1,7 @@
[[basic-concepts]]
== Basic concepts
This document describes Hibernate Query Language (HQL), which is, I suppose we could say, a dialect of the Java (now Jakarta) Persistence Query Language (JPQL).
This document describes Hibernate Query Language (HQL), which is, I suppose we could say, a "dialect" of the Java (now Jakarta) Persistence Query Language (JPQL).
[NOTE]
====
@ -95,7 +95,7 @@ In hindsight, it might have been better to define the whole language as case-sen
[%unbreakable]
[NOTE]
====
Incidentally, it's standard practice to use lowercase keywords in HQL and JPQL.
Incidentally, it's standard practice to use lowercase keywords in HQL.
The use of uppercase keywords indicates an endearing but unhealthy attachment to the culture of the 1970's.
====
@ -207,8 +207,8 @@ This rule is the source of the famous (and controversial) _ternary logic_ of SQL
A logical expression like `firstName='Gavin' and team='Hibernate'` isn't restricted to the values `true` and `false`.
It may also be `null`.
This can in principle lead to some quite unintuitive results: we can't use the law of the excluded middle to reason about logical expressions in SQL!
But in practice, we've once never run into a case where this caused us problems.
This can, in principle, lead to some quite unintuitive results: we can't use the law of the excluded middle to reason about logical expressions in SQL!
But in practice, we've never once run into a case where this caused us problems.
As you probably know, when a logical predicate occurs as a <<where-clause,restriction>>, rows for which the predicate evaluates to `null` are _excluded_ from the result set.
That is, in this context at least, a logical null is interpreted as "effectively false".
@ -325,7 +325,7 @@ For example:
delete Author author where is empty author.books
----
As in SQL, the presence or absence of the `from` keyword has absolutely no effect on the semantics of the `update` statement.
As in SQL, the presence or absence of the `from` keyword has absolutely no effect on the semantics of the `delete` statement.
Just like update statements, delete statements are polymorphic, and affect mapped subclasses of the given entity class.
Therefore, a single HQL `delete` statement might result in multiple SQL delete statements executed against the database.
@ -708,7 +708,7 @@ But at least we don't have to write them explicitly.
[[select-new]]
==== Instantiation
In JPA, and in older versions of Hibernate, this functionality required more ceremony.
In JPQL, and in older versions of Hibernate, this functionality required more ceremony.
[cols="25,~,~,^15"]
|===