feat(nocodb): add DATETIME_DIFF logic for mysql

packages/nocodb/src/lib/db/sql-data-mapper/lib/sql/functionMappings/mysql.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 mysql2 = {
@@ -61,6 +62,26 @@ const mysql2 = {
       END${colAlias}`
     );
   },
+  DATETIME_DIFF: ({ fn, knex, pt, colAlias }: MapFnArgs) => {
+    const datetime_expr1 = fn(pt.arguments[0]);
+    const datetime_expr2 = fn(pt.arguments[1]);
+
+    const unit = convertUnits(
+      pt.arguments[2] ? fn(pt.arguments[2]).bindings[0] : 'seconds',
+      'mysql'
+    );
+
+    if (unit === 'MICROSECOND') {
+      // MySQL doesn't support millisecond
+      // hence change from MICROSECOND to millisecond manually
+      return knex.raw(
+        `TIMESTAMPDIFF(${unit}, ${datetime_expr2}, ${datetime_expr1}) div 1000 ${colAlias}`
+      );
+    }
+    return knex.raw(
+      `TIMESTAMPDIFF(${unit}, ${datetime_expr2}, ${datetime_expr1}) ${colAlias}`
+    );
+  },
   WEEKDAY: ({ fn, knex, pt, colAlias }: MapFnArgs) => {
     // WEEKDAY() returns an index from 0 to 6 for Monday to Sunday
     return knex.raw(