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* split up select.md * array-join.md basic refactoring * distinct.md basic refactoring * format.md basic refactoring * from.md basic refactoring * group-by.md basic refactoring * having.md basic refactoring * additional index.md refactoring * into-outfile.md basic refactoring * join.md basic refactoring * limit.md basic refactoring * limit-by.md basic refactoring * order-by.md basic refactoring * prewhere.md basic refactoring * adjust operators/index.md links * adjust sample.md links * adjust more links * adjust operatots links * fix some links * adjust aggregate function article titles * basic refactor of remaining select clauses * absolute paths in make_links.sh * run make_links.sh * remove old select.md locations * translate docs/es * translate docs/fr * translate docs/fa * remove old operators.md location * change operators.md links * adjust links in docs/es * adjust links in docs/es * minor texts adjustments * wip * update machine translations to use new links * fix changelog * es build fixes * get rid of some select.md links * temporary adjust ru links * temporary adjust more ru links * improve curly brace handling * adjust ru as well * fa build fix * ru link fixes * zh link fixes * temporary disable part of anchor checks
81 lines
2.0 KiB
Markdown
81 lines
2.0 KiB
Markdown
---
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machine_translated: true
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machine_translated_rev: 72537a2d527c63c07aa5d2361a8829f3895cf2bd
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---
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# AVEC la Clause {#with-clause}
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Cette section prend en charge les Expressions de Table courantes ([CTE](https://en.wikipedia.org/wiki/Hierarchical_and_recursive_queries_in_SQL)), de sorte que les résultats de `WITH` la clause peut être utilisé à l'intérieur `SELECT` clause.
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## Limitation {#limitations}
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1. Les requêtes récursives ne sont pas prises en charge.
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2. Lorsque la sous-requête est utilisée à l'intérieur avec section, son résultat doit être scalaire avec exactement une ligne.
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3. Les résultats d'Expression ne sont pas disponibles dans les sous-requêtes.
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## Exemple {#examples}
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**Exemple 1:** Utilisation d'une expression constante comme “variable”
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``` sql
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WITH '2019-08-01 15:23:00' as ts_upper_bound
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SELECT *
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FROM hits
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WHERE
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EventDate = toDate(ts_upper_bound) AND
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EventTime <= ts_upper_bound
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```
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**Exemple 2:** De les expulser, somme(octets) résultat de l'expression de clause SELECT de la liste de colonnes
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``` sql
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WITH sum(bytes) as s
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SELECT
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formatReadableSize(s),
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table
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FROM system.parts
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GROUP BY table
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ORDER BY s
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```
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**Exemple 3:** Utilisation des résultats de la sous-requête scalaire
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``` sql
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/* this example would return TOP 10 of most huge tables */
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WITH
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(
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SELECT sum(bytes)
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FROM system.parts
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WHERE active
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) AS total_disk_usage
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SELECT
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(sum(bytes) / total_disk_usage) * 100 AS table_disk_usage,
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table
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FROM system.parts
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GROUP BY table
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ORDER BY table_disk_usage DESC
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LIMIT 10
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```
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**Exemple 4:** Réutilisation de l'expression dans la sous-requête
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Comme solution de contournement pour la limitation actuelle de l'utilisation de l'expression dans les sous-requêtes, Vous pouvez la dupliquer.
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``` sql
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WITH ['hello'] AS hello
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SELECT
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hello,
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*
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FROM
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(
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WITH ['hello'] AS hello
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SELECT hello
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)
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```
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``` text
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┌─hello─────┬─hello─────┐
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│ ['hello'] │ ['hello'] │
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└───────────┴───────────┘
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```
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