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update the HQL chapter to acknowledge changes in JPA 3.1

This commit is contained in:
Gavin King 2022-10-05 16:21:56 +02:00
parent a7bb19a2ea
commit f70d09175a
2 changed files with 120 additions and 149 deletions
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255
documentation/src/main/asciidoc/userguide/chapters/query/hql/QueryLanguage.adoc
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@ -114,7 +114,7 @@ We don't necessarily _recommend_ leaving off the `select` list.
[NOTE]
====
JPQL requires a `select` clause, whereas HQL does not.
HQL doesn't require a `select` clause, but JPQL _does_.
Naturally, the previous query may be written with a `select` clause:
@ -429,11 +429,12 @@ Again there is some flexibility.
| Datetime | `java.sql.Timestamp` | `current_timestamp` | `current timestamp`
|===
Of these, only `local date`, `local time`, `local datetime`, `current_date`, `current_time`, and `current_timestamp` are defined by the JPQL specification.
[IMPORTANT]
====
Of these, only `current_date`, `current_time`, and `current_timestamp` are defined by the JPQL specification.
However, the use of date and time types from the `java.sql` package is strongly discouraged, so we encourage the use of the HQL extensions.
The use of date and time types from the `java.sql` package is strongly discouraged!
Always use `java.time` types in new code.
====
[[hql-duration-literals]]
@ -446,6 +447,8 @@ There are two sorts of duration in HQL:
Literal duration expressions are of form `n unit`, for example `1 day` or `10 year` or `100 nanosecond`.
The unit may be: `day`, `month`, `quarter`, `year`, `second`, `minute`, `hour`, or `nanosecond`.
[NOTE]
====
A HQL duration is considered to map to a Java `java.time.Duration`, but semantically they're perhaps more similar to an ANSI SQL `INTERVAL` type.
@ -734,6 +737,20 @@ include::{sourcedir}/HQLTest.java[tags=hql-coalesce-example]
TIP: HQL allows `ifnull()` as a synonym for `coalesce()` in the case of exactly two arguments.
[[hql-function-extract]]
===== `extract()`
Extracts a field of a datetime.
Field types include: `day`, `month`, `year`, `second`, `minute`, `hour`, `day of week`, `day of month`, `week of year`, `date`, `time` and more.
For a full list of field types, see the Javadoc for https://docs.jboss.org/hibernate/orm/{majorMinorVersion}/javadocs/org/hibernate/query/TemporalUnit.html[`TemporalUnit`].
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-extract-function-example]
----
====
===== `size()`
The number of elements of a collection or to-many association.
@ -746,6 +763,11 @@ include::{sourcedir}/HQLTest.java[tags=hql-size-example]
----
====
[[jpql-string-functions]]
==== JPQL functions for working with strings
JPQL defines a number of functions for working with strings.
===== `concat()`
Produces a string by concatenating its arguments.
@ -758,6 +780,18 @@ include::{sourcedir}/HQLTest.java[tags=hql-concat-function-example]
----
====
===== `locate()`
Locates a string within another string.
The third argument (optional) is used to specify a position at which to start the search.
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-locate-function-example]
----
====
===== `substring()`
A substring of the given string.
@ -771,28 +805,10 @@ include::{sourcedir}/HQLTest.java[tags=hql-substring-function-example]
----
====
===== `upper()`
The given string, with lowercase characters converted to uppercase.
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-upper-function-example]
----
====
===== `lower()`
The given string, with uppercase characters converted to lowercase.
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-lower-function-example]
----
====
===== `trim()`
Follows the semantics of the SQL `trim()` function.
Follows the syntax and semantics of the ANSI SQL `trim()` function.
May be used to trim `leading` characters, `trailing` characters, or both.
====
[source, JAVA, indent=0]
@ -801,87 +817,64 @@ include::{sourcedir}/HQLTest.java[tags=hql-trim-function-example]
----
====
===== `length()`
The length of a string.
Finally, there's three more functions for working with strings that are easy to understand.
|===
| JPQL Function | Purpose | Signature
| `length()` | The length of the string | `length(s)`
| `upper()` | The string, with lowercase characters converted to uppercase | `upper(s)`
| `lower()` | The string, with uppercase characters converted to lowercase | `lower(s)`
|===
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-length-function-example]
----
====
===== `locate()`
Locates a string within another string.
The third argument (optional) is used to specify a position at which to start the search.
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-locate-function-example]
include::{sourcedir}/HQLTest.java[tags=hql-upper-function-example]
----
//[source, JAVA, indent=0]
//----
//include::{sourcedir}/HQLTest.java[tags=hql-lower-function-example]
//----
====
===== `abs()`
The magnitude of a numeric value.
[[jpql-numeric-functions]]
==== JPQL numeric functions
Of course, JPQL also defines a number of functions for working with numeric values.
|===
| JPQL Function | Purpose | Signature
| `abs()` | The magnitude of a number | `abs(x)`
| `sign()` | The sign of a number | `sign(x)`
| `mod()` | Remainder of integer division | `mod(n,d)`
| `sqrt()` | Square root of a number | `sqrt(x)`
| `exp()` | Exponential function | `exp(x)`
| `power()` | Exponentiation | `power(x,y)`
| `ln()` | Natural logarithm | `ln(x)`
| `round()` | Numeric rounding | `round(number, places)`
| `floor()` | Floor function | `floor(x)`
| `ceiling()` | Ceiling function | `ceiling(x)`
|===
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-abs-function-example]
----
====
===== `mod()`
Calculates the remainder of dividing the first argument by the second.
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-mod-function-example]
----
====
===== `sqrt()`
The square root of a numeric value.
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-sqrt-function-example]
----
====
//
//CURRENT_DATE::
//Returns the database current date.
//
//====
//[source, JAVA, indent=0]
//----
//include::{sourcedir}/HQLTest.java[tags=hql-current-date-function-example]
//----
//====
//
//CURRENT_TIME::
//Returns the database current time.
//
//====
//[source, JAVA, indent=0]
//----
//include::{sourcedir}/HQLTest.java[tags=hql-current-time-function-example]
//----
//====
//
//CURRENT_TIMESTAMP::
//Returns the database current timestamp.
//
//====
//[source, JAVA, indent=0]
//----
//include::{sourcedir}/HQLTest.java[tags=hql-current-timestamp-function-example]
//----
//====
We have not included <<hql-aggregate-functions,aggregate functions>> in this list, because their purpose is more specialized.
@ -913,38 +906,6 @@ include::{sourcedir}/HQLTest.java[tags=hql-str-function-example]
----
====
[[hql-function-extract]]
===== `extract()`
Extracts a field of a datetime.
Field types include: `day`, `month`, `year`, `second`, `minute`, `hour`, `day of week`, `day of month`, `week of year`, `date`, `time` and more.
For a full list of field types, see the Javadoc for https://docs.jboss.org/hibernate/orm/{majorMinorVersion}/javadocs/org/hibernate/query/TemporalUnit.html[`TemporalUnit`].
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-extract-function-example]
----
====
The following synonyms for `extract()` are also provided:
|===
| `year(x)` | `extract(year from x)`
| `month(x)` | `extract(month from x)`
| `day(x)` | `extract(day from x)`
| `hour(x)` | `hour(year from x)`
| `minute(x)` | `minute(year from x)`
| `second(x)` | `second(year from x)`
|===
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-year-function-example]
----
====
===== `collate()`
Selects a collation to be used for its string-valued argument.
@ -963,28 +924,6 @@ The syntax is `format(datetime as pattern)`, and the pattern must be written in
For a full list of `format()` pattern elements, see the Javadoc for https://docs.jboss.org/hibernate/orm/{majorMinorVersion}/javadocs/org/hibernate/dialect/Dialect.html#appendDatetimeFormat[`Dialect#appendDatetimeFormat`].
[[hql-function-sql]]
===== `sql()`
Renders a SQL fragment by unquoting the pattern string literal arguments.
Use cases that require the use of SQL features that are unsupported in HQL,
e.g. functions with special syntax, would usually require a switch to native queries,
but the `sql` function provides a way to make use of certain SQL fragments within an HQL query.
The syntax is `sql(pattern[, argN]*)`, where pattern must be a string literal but other arguments may be of any type.
The pattern literal is unquoted and will be used for rendering the SQL fragment.
Occurrences of question marks `?` in the pattern are replaced with additional arguments passed to the function.
Examples:
```sql
-- Cast to some native type
select c from Computer c where c.ipAddress = sql('?::inet', '127.0.0.1')
-- Use some native operator
select h from Human h order by sql('(? <-> ?)', h.workLocation, h.homeLocation)
```
[[hql-list-functions]]
===== `element()` and `index()`
@ -1028,21 +967,34 @@ Next, functions for working with numeric values:
|===
| HQL Function | Purpose | Signature | Notes on naming
| `sign()` | The sign of a number | `sign(x)` | Universal in SQL dialects
| `exp()` | Exponential function | `exp(x)` | Universal in SQL dialects
| `power()` | Exponentiation | `power(x,y)` | Universal in SQL dialects
| `ln()` | Natural logarithm | `ln(x)` | Very common in SQL dialects
| `log10()` | Base-10 logarithm | `log10(x)` | Very common in SQL dialects
| `log()` | Arbitrary-base logarithm | `log(b,x)` | Very common in SQL dialects
| `pi` | &#960; | `pi` | Very common in SQL dialects
| `sin()`, `cos()`, `tan()`, `asin()`, `acos()`, `atan()`, `atan2()` | Basic trigonometric functions | `sin(theta)`, `cos(theta)`, `atan2(opposite, adjacent)` | Very common in SQL dialects
| `round()` | Numeric rounding | As usual: `round(number, places)` | Very common in SQL dialects
| `floor()` | Floor function | `floor(x)` | Universal in SQL dialects
| `ceiling()` | Ceiling function | `ceiling(x)` | Very common in SQL dialects
| `least()` | Return the smallest of the given arguments | `least(x, y, z)` | Very common in SQL dialects
| `greatest()` | Return the largest of the given arguments | `greatest(x, y, z)` | Very common in SQL dialects
|===
Next, the following functions are abbreviations for `extract()`:
|===
| HQL Function | Long form using `extract()`
| `year(x)` | `extract(year from x)`
| `month(x)` | `extract(month from x)`
| `day(x)` | `extract(day from x)`
| `hour(x)` | `extract(year from x)`
| `minute(x)` | `extract(year from x)`
| `second(x)` | `extract(year from x)`
|===
====
[source, JAVA, indent=0]
----
include::{sourcedir}/HQLTest.java[tags=hql-year-function-example]
----
====
Finally, functions that evaluate the id, version, or natural id of an entity, or the foreign key of a to-one association:
[[hql-model-functions]]
@ -1092,6 +1044,25 @@ include::{sourcedir}/HQLTest.java[tags=hql-native-function-example]
----
====
[[hql-function-sql]]
==== Embedding native SQL in HQL
The special function `sql()` allows the use of native SQL fragments inside an HQL query.
The signature of this function is `sql(pattern[, argN]*)`, where `pattern` must be a string literal but the remaining arguments may be of any type.
The pattern literal is unquoted and embedded in the generated SQL.
Occurrences of `?` in the pattern are replaced with the remaining arguments of the function.
====
[source, SQL, indent=0]
----
-- Cast to some native type
select c from Computer c where c.ipAddress = sql('?::inet', '127.0.0.1')
-- Use some native operator
select h from Human h order by sql('(? <-> ?)', h.workLocation, h.homeLocation)
----
====
[[hql-conditional-expressions]]
=== Predicates

14
documentation/src/test/java/org/hibernate/userguide/hql/HQLTest.java
View File

@ -255,11 +255,11 @@ public class HQLTest extends BaseEntityManagerFunctionalTestCase {
doInJPA(this::entityManagerFactory, entityManager -> {
//tag::hql-insert-example[]
entityManager.createQuery(
"insert Person (id, name) " +
"values (101L, 'J A Doe III'), " +
"(102L, 'J X Doe'), " +
"(103L, 'John Doe, Jr')")
.executeUpdate();
"insert Person (id, name) " +
"values (101L, 'J A Doe III'), " +
"(102L, 'J X Doe'), " +
"(103L, 'John Doe, Jr')")
.executeUpdate();
//end::hql-insert-example[]
});
}
@ -268,8 +268,8 @@ public class HQLTest extends BaseEntityManagerFunctionalTestCase {
public void hql_insert_with_sequence_example() {
doInJPA( this::entityManagerFactory, entityManager -> {
entityManager.createQuery(
"insert Person (name) values ('Jane Doe2')" )
.executeUpdate();
"insert Person (name) values ('Jane Doe2')" )
.executeUpdate();
});
}