SQL: Implement CURRENT_DATE (#38175)

Since DATE data type is now available, this implements the
`CURRENT_DATE/CURRENT_DATE()/TODAY()` similar to `CURRENT_TIMESTAMP`.

Closes: #38160

Author: matriv

docs/reference/sql/functions/date-time.asciidoc

@@ -93,6 +93,48 @@ include-tagged::{sql-specs}/docs.csv-spec[dtIntervalMul]
 
 beta[]
 
+[[sql-functions-current-date]]
+==== `CURRENT_DATE/CURDATE`
+
+.Synopsis:
+[source, sql]
+--------------------------------------------------
+CURRENT_DATE
+CURRENT_DATE()
+--------------------------------------------------
+
+*Input*: _none_
+
+*Output*: date
+
+.Description:
+
+Returns the date (no time part) when the current query reached the server.
+It can be used both as a keyword: `CURRENT_DATE` or as a function with no arguments: `CURRENT_DATE()`.
+
+[NOTE]
+Unlike CURRENT_DATE, `CURDATE()` can only be used as a function with no arguments and not as a keyword.
+
+This method always returns the same value for its every occurrence within the same query.
+
+["source","sql",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{sql-specs}/docs.csv-spec[curDate]
+--------------------------------------------------
+
+["source","sql",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{sql-specs}/docs.csv-spec[curDateFunction]
+--------------------------------------------------
+
+Typically, this function (as well as its twin <<sql-functions-today,TODAY())>> function
+is used for relative date filtering:
+
+["source","sql",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{sql-specs}/docs.csv-spec[filterToday]
+--------------------------------------------------
+
 [[sql-functions-current-timestamp]]
 ==== `CURRENT_TIMESTAMP`
 
@@ -115,7 +157,7 @@ Returns the date/time when the current query reached the server.
 As a function, `CURRENT_TIMESTAMP()` accepts _precision_ as an optional
 parameter for rounding the second fractional digits (nanoseconds).
 
-This method always returns the same value within a query.
+This method always returns the same value for its every occurrence within the same query.
 
 ["source","sql",subs="attributes,callouts,macros"]
 --------------------------------------------------
@@ -422,7 +464,8 @@ NOW()
 .Description:
 
 This function offers the same functionality as <<sql-functions-current-timestamp,CURRENT_TIMESTAMP()>> function: returns
-the datetime when the current query reached the server. This method always returns the same value within a query.
+the datetime when the current query reached the server. This method always returns the same value for its every
+occurrence within the same query.
 
 ["source","sql",subs="attributes,callouts,macros"]
 --------------------------------------------------
@@ -485,6 +528,38 @@ Extract the year quarter the date/datetime falls in.
 include-tagged::{sql-specs}/docs.csv-spec[quarter]
 --------------------------------------------------
 
+[[sql-functions-today]]
+==== `TODAY`
+
+.Synopsis:
+[source, sql]
+--------------------------------------------------
+TODAY()
+--------------------------------------------------
+
+*Input*: _none_
+
+*Output*: date
+
+.Description:
+
+This function offers the same functionality as <<sql-functions-current-date,CURRENT_DATE()>> function: returns
+the date when the current query reached the server. This method always returns the same value for its every occurrence
+within the same query.
+
+["source","sql",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{sql-specs}/docs.csv-spec[todayFunction]
+--------------------------------------------------
+
+Typically, this function (as well as its twin <<sql-functions-current-timestamp,CURRENT_TIMESTAMP())>> function is used
+for relative date filtering:
+
+["source","sql",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{sql-specs}/docs.csv-spec[filterToday]
+--------------------------------------------------
+
 [[sql-functions-datetime-week]]
 ==== `WEEK_OF_YEAR/WEEK`
 

x-pack/plugin/sql/qa/src/main/java/org/elasticsearch/xpack/sql/qa/cli/ShowTestCase.java

@@ -91,6 +91,7 @@ public void testShowFunctionsLikeInfix() throws IOException {
         assertThat(readLine(), RegexMatcher.matches("\\s*ISODAYOFWEEK\\s*\\|\\s*SCALAR\\s*"));
         assertThat(readLine(), RegexMatcher.matches("\\s*ISO_DAY_OF_WEEK\\s*\\|\\s*SCALAR\\s*"));
         assertThat(readLine(), RegexMatcher.matches("\\s*MINUTE_OF_DAY\\s*\\|\\s*SCALAR\\s*"));
+        assertThat(readLine(), RegexMatcher.matches("\\s*TODAY\\s*\\|\\s*SCALAR\\s*"));
         assertEquals("", readLine());
     }
 }

x-pack/plugin/sql/qa/src/main/resources/command.csv-spec

@@ -31,6 +31,8 @@ ISNULL           |CONDITIONAL
 LEAST            |CONDITIONAL
 NULLIF           |CONDITIONAL
 NVL              |CONDITIONAL
+CURDATE          |SCALAR
+CURRENT_DATE     |SCALAR
 CURRENT_TIMESTAMP|SCALAR
 DAY              |SCALAR
 DAYNAME          |SCALAR
@@ -65,7 +67,8 @@ MONTH_OF_YEAR    |SCALAR
 NOW              |SCALAR
 QUARTER          |SCALAR         
 SECOND           |SCALAR         
-SECOND_OF_MINUTE |SCALAR         
+SECOND_OF_MINUTE |SCALAR
+TODAY            |SCALAR
 WEEK             |SCALAR         
 WEEK_OF_YEAR     |SCALAR         
 YEAR             |SCALAR         
@@ -175,6 +178,7 @@ HOUR_OF_DAY    |SCALAR
 ISODAYOFWEEK   |SCALAR
 ISO_DAY_OF_WEEK|SCALAR
 MINUTE_OF_DAY  |SCALAR         
+TODAY          |SCALAR
 ;
 
 showTables

x-pack/plugin/sql/qa/src/main/resources/date.csv-spec

@@ -2,6 +2,73 @@
 // Date
 //
 
+currentDateKeywordWithDivision
+SELECT YEAR(CURRENT_TIMESTAMP) / 1000 AS result;
+
+    result
+---------------
+2
+;
+
+currentDateFunctionNoArgsWithDivision
+SELECT YEAR(CURRENT_TIMESTAMP()) / 1000 AS result;
+
+    result
+---------------
+2
+;
+
+todayWithDivision
+SELECT YEAR(TODAY()) / 1000 AS result;
+
+    result
+---------------
+2
+;
+
+todayIntervalSubstraction
+SELECT TRUNCATE(YEAR(TODAY() - INTERVAL 50 YEARS) / 1000) AS result;
+
+    result
+---------------
+1
+;
+
+
+currentDateFilter
+SELECT first_name FROM test_emp WHERE hire_date > CURRENT_DATE() - INTERVAL 25 YEARS ORDER BY first_name ASC LIMIT 10;
+
+    first_name
+-----------------
+Kazuhito
+Kenroku
+Lillian
+Mayumi
+Mingsen
+Sailaja
+Saniya
+Shahaf
+Suzette
+Tuval
+;
+
+currentDateFilterScript
+SELECT first_name, TRUNCATE(YEAR(hire_date) - YEAR(TODAY()) / 1000) AS filter FROM test_emp
+WHERE TRUNCATE(YEAR(hire_date) - YEAR(TODAY()) / 1000) > 1990 ORDER BY first_name ASC LIMIT 10;
+
+  first_name   |  filter
+Cristinel      |1991
+Kazuhito       |1993
+Kenroku        |1992
+Lillian        |1997
+Magy           |1991
+Mayumi         |1993
+Mingsen        |1992
+Sailaja        |1994
+Saniya         |1992
+Shahaf         |1993
+;
+
 dateExtractDateParts
 SELECT
 DAY(CAST(birth_date AS DATE)) d,
@@ -75,3 +142,23 @@ SELECT YEAR(CAST('2019-01-21' AS DATE) + INTERVAL '1-2' YEAR TO MONTH) AS y, MON
 y:i       | m:i
 2020      | 3
 ;
+
+orderByCurrentDate
+SELECT first_name FROM test_emp ORDER BY TODAY(), first_name LIMIT 5;
+
+  first_name
+---------------
+Alejandro
+Amabile
+Anneke
+Anoosh
+Arumugam
+;
+
+groupByCurrentDate
+SELECT MAX(salary) FROM test_emp GROUP BY TODAY();
+
+  MAX(salary)
+---------------
+74999
+;

x-pack/plugin/sql/qa/src/main/resources/datetime.sql-spec

@@ -120,6 +120,12 @@ SELECT DAY_OF_WEEK(birth_date) day, COUNT(*) c FROM test_emp WHERE DAY_OF_WEEK(b
 currentTimestampYear
 SELECT YEAR(CURRENT_TIMESTAMP()) AS result;
 
+orderByCurrentTimestamp
+SELECT first_name FROM test_emp ORDER BY NOW(), first_name NULLS LAST LIMIT 5;
+
+groupByCurrentTimestamp
+SELECT MAX(salary) AS max FROM test_emp GROUP BY NOW();
+
 //
 // H2 uses the local timezone instead of the specified one
 //
@@ -131,3 +137,4 @@ SELECT HOUR(CURRENT_TIMESTAMP()) AS result;
 
 currentTimestampMinute-Ignore
 SELECT MINUTE(CURRENT_TIMESTAMP()) AS result;
+

x-pack/plugin/sql/qa/src/main/resources/docs.csv-spec

@@ -208,6 +208,8 @@ ISNULL           |CONDITIONAL
 LEAST            |CONDITIONAL
 NULLIF           |CONDITIONAL
 NVL              |CONDITIONAL
+CURDATE          |SCALAR
+CURRENT_DATE     |SCALAR
 CURRENT_TIMESTAMP|SCALAR
 DAY              |SCALAR
 DAYNAME          |SCALAR
@@ -242,7 +244,8 @@ MONTH_OF_YEAR    |SCALAR
 NOW              |SCALAR
 QUARTER          |SCALAR         
 SECOND           |SCALAR         
-SECOND_OF_MINUTE |SCALAR         
+SECOND_OF_MINUTE |SCALAR
+TODAY            |SCALAR
 WEEK             |SCALAR         
 WEEK_OF_YEAR     |SCALAR         
 YEAR             |SCALAR         
@@ -365,6 +368,7 @@ HOUR_OF_DAY    |SCALAR
 ISODAYOFWEEK   |SCALAR
 ISO_DAY_OF_WEEK|SCALAR
 MINUTE_OF_DAY  |SCALAR         
+TODAY          |SCALAR
 
 // end::showFunctionsWithPattern
 ;
@@ -2227,18 +2231,50 @@ SELECT WEEK(CAST('1988-01-05T09:22:10Z' AS TIMESTAMP)) AS week, ISOWEEK(CAST('19
 ;
 
 
-currentNow
-// tag::filterNow
-SELECT first_name FROM emp WHERE hire_date > NOW() - INTERVAL 100 YEARS ORDER BY first_name ASC LIMIT 5;
 
-  first_name   
----------------
-Alejandro      
-Amabile        
-Anneke         
-Anoosh         
-Arumugam       
-// end::filterNow
+
+currentDate-Ignore
+// tag::curDate
+SELECT CURRENT_TIMESTAMP AS result;
+
+         result
+------------------------
+2018-12-12
+// end::curDate
+;
+
+currentDateFunction-Ignore
+// tag::curDateFunction
+SELECT CURRENT_TIMESTAMP() AS result;
+
+         result
+------------------------
+2018-12-12
+// end::curDateFunction
+;
+
+todayFunction-Ignore
+// tag::todayFunction
+SELECT TODAY() AS result;
+
+         result
+------------------------
+2018-12-12
+// end::todayFunction
+;
+
+filterToday
+// tag::filterToday
+SELECT first_name FROM emp WHERE hire_date > TODAY() - INTERVAL 25 YEARS ORDER BY first_name ASC LIMIT 5;
+
+ first_name
+------------
+Kazuhito
+Kenroku
+Lillian
+Mayumi
+Mingsen
+// end::filterToday
 ;
 
 currentTimestamp-Ignore
@@ -2282,6 +2318,20 @@ SELECT NOW() AS result;
 // end::nowFunction
 ;
 
+filterNow
+// tag::filterNow
+SELECT first_name FROM emp WHERE hire_date > NOW() - INTERVAL 100 YEARS ORDER BY first_name ASC LIMIT 5;
+
+  first_name
+---------------
+Alejandro
+Amabile
+Anneke
+Anoosh
+Arumugam
+// end::filterNow
+;
+
 ////////////
 // Next two queries need to have the same output, as they should be equivalent.
 // They are used in the "SQL Limitations" page.

x-pack/plugin/sql/src/main/antlr/SqlBase.g4

@@ -236,7 +236,8 @@ castTemplate
     ;
 
 builtinDateTimeFunction
-    : name=CURRENT_TIMESTAMP ('(' precision=INTEGER_VALUE? ')')?
+    : name=CURRENT_DATE ('(' ')')?
+    | name=CURRENT_TIMESTAMP ('(' precision=INTEGER_VALUE? ')')?
     ;
 
 convertTemplate
@@ -337,7 +338,7 @@ string
 // http://developer.mimer.se/validator/sql-reserved-words.tml
 nonReserved
     : ANALYZE | ANALYZED 
-    | CATALOGS | COLUMNS | CURRENT 
+    | CATALOGS | COLUMNS
     | DAY | DEBUG  
     | EXECUTABLE | EXPLAIN 
     | FIRST | FORMAT | FULL | FUNCTIONS
@@ -370,7 +371,7 @@ CATALOG: 'CATALOG';
 CATALOGS: 'CATALOGS';
 COLUMNS: 'COLUMNS';
 CONVERT: 'CONVERT';
-CURRENT: 'CURRENT';
+CURRENT_DATE : 'CURRENT_DATE';
 CURRENT_TIMESTAMP : 'CURRENT_TIMESTAMP';
 DAY: 'DAY';
 DAYS: 'DAYS';