fix(cubesql): Incorrect CASE WHEN generated during ungrouped filtered count (#7859)

Fixes #7858

Author: paveltiunov

packages/cubejs-schema-compiler/src/adapter/BaseQuery.js

@@ -2005,7 +2005,8 @@ export class BaseQuery {
     }
     if (this.ungrouped) {
       if (symbol.type === 'count' || symbol.type === 'countDistinct' || symbol.type === 'countDistinctApprox') {
-        return evaluateSql === '*' ? '1' : this.caseWhenStatement([{ sql: `(${evaluateSql}) IS NOT NULL`, label: `1` }]);
+        const sql = symbol.type === 'countDistinct' || symbol.type === 'countDistinctApprox' ? evaluateSql : this.caseWhenStatement([{ sql: `(${evaluateSql}) IS NOT NULL`, label: `1` }]);
+        return evaluateSql === '*' ? '1' : sql;
       } else {
         return evaluateSql;
       }

packages/cubejs-schema-compiler/test/integration/postgres/sql-generation.test.ts

@@ -212,6 +212,13 @@ describe('SQL Generation', () => {
             sql: \`\${visitors}.source = 'google'\`
           }]
         },
+        unique_google_sourced_checkins: {
+          type: 'countDistinct',
+          sql: 'id',
+          filters: [{
+            sql: \`\${visitors}.source = 'google'\`
+          }]
+        },
         minDate: {
           type: 'min',
           sql: 'created_at'
@@ -1459,6 +1466,30 @@ describe('SQL Generation', () => {
     { visitor_checkins__created_at_day: '2017-01-05T00:00:00.000Z', visitor_checkins__google_sourced_checkins: 1 },
   ]));
 
+  it('ungrouped filtered distinct count', () => runQueryTest({
+    measures: [
+      'visitor_checkins.unique_google_sourced_checkins',
+    ],
+    timezone: 'America/Los_Angeles',
+    order: [{
+      id: 'visitor_checkins.created_at',
+    }],
+    timeDimensions: [{
+      dimension: 'visitor_checkins.created_at',
+      granularity: 'day',
+      dateRange: ['2016-12-01', '2017-03-30'],
+    }],
+    ungrouped: true,
+    allowUngroupedWithoutPrimaryKey: true,
+  }, [
+    { visitor_checkins__created_at_day: '2017-01-02T00:00:00.000Z', visitor_checkins__unique_google_sourced_checkins: null },
+    { visitor_checkins__created_at_day: '2017-01-03T00:00:00.000Z', visitor_checkins__unique_google_sourced_checkins: null },
+    { visitor_checkins__created_at_day: '2017-01-04T00:00:00.000Z', visitor_checkins__unique_google_sourced_checkins: null },
+    { visitor_checkins__created_at_day: '2017-01-04T00:00:00.000Z', visitor_checkins__unique_google_sourced_checkins: null },
+    { visitor_checkins__created_at_day: '2017-01-04T00:00:00.000Z', visitor_checkins__unique_google_sourced_checkins: null },
+    { visitor_checkins__created_at_day: '2017-01-05T00:00:00.000Z', visitor_checkins__unique_google_sourced_checkins: 6 },
+  ]));
+
   it('builds geo dimension', () => runQueryTest({
     dimensions: [
       'visitors.location'