From 210efe162113d74f3894bacd8e6a4b4a5fce975c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Kudzia?=
 <30438339+pakud@users.noreply.github.com>
Date: Mon, 15 Apr 2024 08:50:01 +0200
Subject: [PATCH] documenting alternative syntax that's supported for DATE_ADD,
 DATE_SUB

this is related to issue https://github.com/ClickHouse/ClickHouse/issues/25815

i'm adding examples for:
date_add(date, INTERVAL value unit) and date_sub(date, INTERVAL value unit)

both are covered with a test from https://github.com/ClickHouse/ClickHouse/blob/e3c09e97034b7d26b2280487fa8422a8037caa51/tests/queries/0_stateless/02160_special_functions.sql#L33 ; i think it's worth documenting them as the syntax is familiar to MySQL users [ https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date-add ]
---
 .../functions/date-time-functions.md          | 40 +++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/docs/en/sql-reference/functions/date-time-functions.md b/docs/en/sql-reference/functions/date-time-functions.md
index 3bb9d4e7dbe..7c790e739e0 100644
--- a/docs/en/sql-reference/functions/date-time-functions.md
+++ b/docs/en/sql-reference/functions/date-time-functions.md
@@ -1902,6 +1902,12 @@ If the addition results in a value outside the bounds of the data type, the resu
 date_add(unit, value, date)
 ```
 
+Alternative syntax:
+
+``` sql
+date_add(date, INTERVAL value unit)
+```
+
 Aliases: `dateAdd`, `DATE_ADD`.
 
 **Arguments**
@@ -1941,6 +1947,20 @@ Result:
 └───────────────────────────────────────────────┘
 ```
 
+```sql
+SELECT date_add(toDate('2018-01-01'), INTERVAL 3 YEAR);
+```
+
+Result:
+
+```text
+┌─plus(toDate('2018-01-01'), toIntervalYear(3))─┐
+│                                    2021-01-01 │
+└───────────────────────────────────────────────┘
+```
+
+
+
 **See Also**
 
 - [addDate](#addDate)
@@ -1957,6 +1977,13 @@ If the subtraction results in a value outside the bounds of the data type, the r
 date_sub(unit, value, date)
 ```
 
+Alternative syntax:
+
+``` sql
+date_sub(date, INTERVAL value unit)
+```
+
+
 Aliases: `dateSub`, `DATE_SUB`.
 
 **Arguments**
@@ -1997,6 +2024,19 @@ Result:
 └────────────────────────────────────────────────┘
 ```
 
+``` sql
+SELECT date_sub(toDate('2018-01-01'), INTERVAL 3 YEAR);
+```
+
+Result:
+
+``` text
+┌─minus(toDate('2018-01-01'), toIntervalYear(3))─┐
+│                                     2015-01-01 │
+└────────────────────────────────────────────────┘
+```
+
+
 **See Also**
 
 - [subDate](#subDate)