support CTE statement without use db

fe/fe-core/src/main/java/org/apache/doris/analysis/SelectStmt.java

@@ -25,6 +25,7 @@
 import org.apache.doris.catalog.OlapTable;
 import org.apache.doris.catalog.Table.TableType;
 import org.apache.doris.catalog.Type;
+import org.apache.doris.catalog.View;
 import org.apache.doris.cluster.ClusterNamespace;
 import org.apache.doris.common.AnalysisException;
 import org.apache.doris.common.ColumnAliasGenerator;
@@ -289,6 +290,9 @@ public void getDbs(Analyzer analyzer, Map<String, Database> dbs) throws Analysis
                 } else {
                     dbName = ClusterNamespace.getFullName(analyzer.getClusterName(), tblRef.getName().getDb());
                 }
+                if(withClause_ != null && isViewTableRef(tblRef)){
+                    continue;
+                }
                 if (Strings.isNullOrEmpty(dbName)) {
                     ErrorReport.reportAnalysisException(ErrorCode.ERR_NO_DB_ERROR);
                 }
@@ -313,6 +317,16 @@ public void getDbs(Analyzer analyzer, Map<String, Database> dbs) throws Analysis
         }
     }
 
+    private boolean isViewTableRef(TableRef tblRef) {
+        List<View> views = withClause_.getViews();
+        for(View view : views){
+            if(view.getName().equals(tblRef.getName().toString())){
+                return true;
+            }
+        }
+        return false;
+    }
+
     // Column alias generator used during query rewriting.
     private ColumnAliasGenerator columnAliasGenerator = null;
 

fe/fe-core/src/test/java/org/apache/doris/analysis/SelectStmtTest.java

@@ -520,4 +520,11 @@ public void testSelectHintSetVar() throws Exception {
         planner = dorisAssert.query(sql).internalExecuteOneAndGetPlan();
         Assert.assertEquals(8589934592L, planner.getPlannerContext().getQueryOptions().mem_limit);
     }
+
+    @Test
+    public void testWithWithoutDatabase() throws Exception {
+        String sql = "with tmp as (select count(*) from db1.table1) select * from tmp;";
+        dorisAssert.withoutUseDatabase();
+        dorisAssert.query(sql).explainQuery();
+    }
 }

fe/fe-core/src/test/java/org/apache/doris/utframe/DorisAssert.java

@@ -73,6 +73,11 @@ public DorisAssert useDatabase(String dbName) {
         return this;
     }
 
+    public DorisAssert withoutUseDatabase() {
+        ctx.setDatabase("");
+        return this;
+    }
+
     public DorisAssert withTable(String sql) throws Exception {
         CreateTableStmt createTableStmt = (CreateTableStmt) UtFrameUtils.parseAndAnalyzeStmt(sql, ctx);
         Catalog.getCurrentCatalog().createTable(createTableStmt);