feat: implement dateadd macro

README.md

@@ -27,6 +27,7 @@ This dbt package contains macros for SQL functions to run the dbt project on mul
 - [Multiple databases](#Multiple-databases)
   - [as_varchar](#as_varchar-source)
   - [create_index](#create_index-source)
+  - [date_add](#date_add-source)
   - [date_from_timestamp](#date_from_timestamp-source)
   - [datediff](#datediff-source)
   - [string_agg](#string_agg-source)
@@ -79,6 +80,12 @@ In case you want to create the index on a source table, refer to the table using
 ) }}
 ```
 
+#### dateadd ([source](macros/multiple_databases/dateadd.sql))
+This macro adds a specified number value (as a signed integer) to a specified datepart of an input date value, and then returns that modified value. The datepart can be any of the following values for SQL Server and Snowflake: year, quarter, month, week, day, hour, minute, second, millisecond. For Databricks, the datepart can be any of the following values: year, day, hour, minute, second, millisecond. The difference in weeks is calculated for weeks starting on Monday.
+
+Usage: 
+`{{ pm_utils.dateadd('[datepart]', [number], '[expression]') }}`
+
 #### date_from_timestamp ([source](macros/multiple_databases/date_from_timestamp.sql))
 This macro extracts the date part from a datetime field. 
 

macros/multiple_databases/dateadd.sql

@@ -0,0 +1,19 @@
+{%- macro dateadd(datepart, number, datetime_field) -%}
+{%- if target.type == 'snowflake' -%}
+    dateadd({{ datepart }}, {{ number }}, try_to_timestamp(to_varchar({{ datetime_field }})))
+{%- elif target.type == 'sqlserver' -%}
+    dateadd({{ datepart }}, {{ number }}, try_convert(datetime2, {{ datetime_field }}))
+{%- elif target.type == 'databricks' -%}
+    {%- if datepart == 'second' -%}
+        timestamp_millis(bigint(unix_millis({{ datetime_field }}) + {{ number }}*1000))
+    {%- elif datepart == 'minute' -%}
+        timestamp_millis(bigint(unix_millis({{ datetime_field }}) + {{ number }}*6000))
+    {%- elif datepart == 'hour' -%}
+        timestamp_millis(bigint(unix_millis({{ datetime_field }}) + {{ number }}*3600000))
+    {%- elif datepart == 'day' -%}
+        timestamp_millis(bigint(unix_millis({{ datetime_field }}) + {{ number }}*86400000))
+    {%- elif datepart == 'year' -%}
+        timestamp_millis(bigint(add_months({{ datetime_field }}, {{ number }}*12) + bigint(unix_millis({{ datetime_field }})) - bigint(unix_millis(date_trunc('DD', {{ datetime_field }})))))
+    {%- endif -%}
+{%- endif -%}
+{%- endmacro -%}