feat(nocodb): add DATETIME_DIFF logic for pg

packages/nocodb/src/lib/db/sql-data-mapper/lib/sql/functionMappings/pg.ts

@@ -1,6 +1,7 @@
 import dayjs from 'dayjs';
 import { MapFnArgs } from '../mapFunctionName';
 import commonFns from './commonFns';
+import { convertUnits } from '../helpers/convertUnits';
 import { getWeekdayByText } from '../helpers/formulaFnHelper';
 
 const pg = {
@@ -50,6 +51,53 @@ const pg = {
       )}')::interval${colAlias}`
     );
   },
+  DATETIME_DIFF: ({ fn, knex, pt, colAlias }: MapFnArgs) => {
+    const datetime_expr1 = fn(pt.arguments[0]);
+    const datetime_expr2 = fn(pt.arguments[1]);
+    const rawUnit = pt.arguments[2]
+      ? fn(pt.arguments[2]).bindings[0]
+      : 'seconds';
+    let sql;
+    const unit = convertUnits(rawUnit, 'pg');
+    switch (unit) {
+      case 'second':
+        sql = `EXTRACT(EPOCH from (${datetime_expr1}::TIMESTAMP - ${datetime_expr2}::TIMESTAMP))::INTEGER`;
+        break;
+      case 'minute':
+        sql = `EXTRACT(EPOCH from (${datetime_expr1}::TIMESTAMP - ${datetime_expr2}::TIMESTAMP))::INTEGER / 60`;
+        break;
+      case 'milliseconds':
+        sql = `EXTRACT(EPOCH from (${datetime_expr1}::TIMESTAMP - ${datetime_expr2}::TIMESTAMP))::INTEGER / 3600`;
+        break;
+      case 'week':
+        sql = `TRUNC(DATE_PART('day', ${datetime_expr1}::TIMESTAMP - ${datetime_expr2}::TIMESTAMP) / 7)`;
+        break;
+      case 'month':
+        sql = `(
+                DATE_PART('year', ${datetime_expr1}::TIMESTAMP) - 
+                DATE_PART('year', ${datetime_expr2}::TIMESTAMP)
+               ) * 12 + (
+                DATE_PART('month', ${datetime_expr1}::TIMESTAMP) - 
+                DATE_PART('month', ${datetime_expr2}::TIMESTAMP)
+               )`;
+        break;
+      case 'quarter':
+        sql = `((EXTRACT(QUARTER FROM ${datetime_expr1}::TIMESTAMP) + 
+                    DATE_PART('year', AGE(${datetime_expr1},'1900/01/01')) * 4) - 1) - 
+                ((EXTRACT(QUARTER FROM ${datetime_expr2}::TIMESTAMP) + 
+                    DATE_PART('year', AGE(${datetime_expr2},'1900/01/01')) * 4) - 1)`;
+        break;
+      case 'year':
+        sql = `DATE_PART('year', ${datetime_expr1}::TIMESTAMP) - DATE_PART('year', ${datetime_expr2}::TIMESTAMP)`;
+        break;
+      case 'day':
+        sql = `DATE_PART('day', ${datetime_expr1}::TIMESTAMP - ${datetime_expr2}::TIMESTAMP)`;
+        break;
+      default:
+        sql = '';
+    }
+    return knex.raw(`${sql} ${colAlias}`);
+  },
   WEEKDAY: ({ fn, knex, pt, colAlias }: MapFnArgs) => {
     // isodow: the day of the week as Monday (1) to Sunday (7)
     // WEEKDAY() returns an index from 0 to 6 for Monday to Sunday