feat: implement dateadd macro

README.md

@@ -28,6 +28,7 @@ This dbt package contains macros for SQL functions to run the dbt project on mul
   - [as_varchar](#as_varchar-source)
   - [charindex](#charindex-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)
@@ -86,6 +87,12 @@ 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) of the specified datepart to an input date or datetime and then returns that modified value. The datepart can be any of the following values: year, quarter, month, week, day, hour, minute, second, millisecond.
+
+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 +1,33 @@
+{%- macro dateadd(datepart, number, date_or_datetime_field) -%}
+{%- if target.type == 'snowflake' -%}
+    dateadd({{ datepart }}, {{ number }}, try_to_timestamp(to_varchar({{ date_or_datetime_field }})))
+{%- elif target.type == 'sqlserver' -%}
+    dateadd({{ datepart }}, {{ number }}, try_convert(datetime2, {{ date_or_datetime_field }}))
+{%- elif target.type == 'databricks' -%}
+    {%- set datetime_field -%}
+        try_to_timestamp({{ date_or_datetime_field }})
+    {%- endset -%}
+    {%- set time_field -%}
+        unix_millis({{ datetime_field }}) - unix_millis(date_trunc('DD', {{ datetime_field }}))
+    {%- endset -%}
+    {%- if datepart == 'millisecond' -%}
+        timestamp_millis(unix_millis({{ datetime_field }}) + {{ number }})
+    {%- elif datepart == 'second' -%}
+        timestamp_millis(unix_millis({{ datetime_field }}) + {{ number }}*1000)
+    {%- elif datepart == 'minute' -%}
+        timestamp_millis(unix_millis({{ datetime_field }}) + {{ number }}*60000)
+    {%- elif datepart == 'hour' -%}
+        timestamp_millis(unix_millis({{ datetime_field }}) + {{ number }}*3600000)
+    {%- elif datepart == 'day' -%}
+        timestamp_millis(unix_millis(try_to_timestamp(date_add(to_date({{ datetime_field }}), {{ number }}))) + {{ time_field }})
+    {%- elif datepart == 'week' -%}
+        timestamp_millis(unix_millis(try_to_timestamp(date_add(to_date({{ datetime_field }}), {{ number }}*7))) + {{ time_field }})
+    {%- elif datepart == 'month' -%}
+        timestamp_millis(unix_millis(try_to_timestamp(add_months(to_date({{ datetime_field }}), {{ number }}))) + {{ time_field }})
+    {%- elif datepart == 'quarter' -%}
+        timestamp_millis(unix_millis(try_to_timestamp(add_months(to_date({{ datetime_field }}), {{ number }}*3))) + {{ time_field }})
+    {%- elif datepart == 'year' -%}
+        timestamp_millis(unix_millis(try_to_timestamp(add_months(to_date({{ datetime_field }}), {{ number }}*12))) + {{ time_field }})
+    {%- endif -%}
+{%- endif -%}
+{%- endmacro -%}