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new 1d49dc9 Add doc for EXTRACT, date_part (#1991)
1d49dc9 is described below
commit 1d49dc9e5ff7b81226cb8f59e89e977ce2af1435
Author: Yang Jiang <[email protected]>
AuthorDate: Wed Mar 16 12:14:16 2022 +0800
Add doc for EXTRACT, date_part (#1991)
* add doc for EXTRACT, date_part
* add
* prettier
* fix comment
---
docs/source/user-guide/sql/datafusion-functions.md | 22 ++++++++++++++++++++++
docs/source/user-guide/sql/sql_status.md | 1 +
2 files changed, 23 insertions(+)
diff --git a/docs/source/user-guide/sql/datafusion-functions.md
b/docs/source/user-guide/sql/datafusion-functions.md
index aa80012..0c50208 100644
--- a/docs/source/user-guide/sql/datafusion-functions.md
+++ b/docs/source/user-guide/sql/datafusion-functions.md
@@ -84,3 +84,25 @@ Note that `CAST(.. AS Timestamp)` converts to Timestamps
with Nanosecond resolut
- Other Timestamp() columns or values
Note that `CAST(.. AS Timestamp)` converts to Timestamps with Nanosecond
resolution; this function is the only way to convert/cast to seconds resolution.
+
+## `EXTRACT, date_part`
+
+`EXTRACT(field FROM source)`
+
+- The `extract` function retrieves subfields such as year or hour from
date/time values.
+ `source` must be a value expression of type timestamp, Data32, or Data64.
`field` is an identifier that selects what field to extract from the source
value.
+ The `extract` function returns values of type u32.
+ - `year` :`EXTRACT(year FROM to_timestamp('2020-09-08T12:00:00+00:00')) ->
2020`
+ - `month`:`EXTRACT(month FROM to_timestamp('2020-09-08T12:00:00+00:00')) ->
9`
+ - `week` :`EXTRACT(week FROM to_timestamp('2020-09-08T12:00:00+00:00')) ->
23`
+ - `day`: `EXTRACT(day FROM to_timestamp('2020-09-08T12:00:00+00:00')) -> 8`
+ - `hour`: `EXTRACT(hour FROM to_timestamp('2020-09-08T12:00:00+00:00')) ->
12`
+ - `minute`: `EXTRACT(minute FROM to_timestamp('2020-09-08T12:01:00+00:00'))
-> 1`
+ - `second`: `EXTRACT(second FROM to_timestamp('2020-09-08T12:00:03+00:00'))
-> 3`
+
+`date_part('field', source)`
+
+- The `date_part` function is modeled on the postgres equivalent to the
SQL-standard function `extract`.
+ Note that here the field parameter needs to be a string value, not a name.
+ The valid field names for `date_part` are the same as for `extract`.
+ - `date_part('second', to_timestamp('2020-09-08T12:00:12+00:00')) -> 12`
diff --git a/docs/source/user-guide/sql/sql_status.md
b/docs/source/user-guide/sql/sql_status.md
index 0df14e5..a8ecc5e 100644
--- a/docs/source/user-guide/sql/sql_status.md
+++ b/docs/source/user-guide/sql/sql_status.md
@@ -84,6 +84,7 @@
- [x]
[to_timestamp_millis](docs/user-guide/book/sql/datafusion-functions.html#to_timestamp_millis)
- [x]
[to_timestamp_micros](docs/user-guide/book/sql/datafusion-functions.html#to_timestamp_micros)
- [x]
[to_timestamp_seconds](docs/user-guide/book/sql/datafusion-functions.html#to_timestamp_seconds)
+ - [x] [extract,
date_part](docs/user-guide/book/sql/datafusion-functions.html#`EXTRACT,
date_part`)
- nested functions
- [x] Array of columns
- [x] Schema Queries
