[fix](planner) ctas should not change any meta of column in source ta…

…ble (#24767)

if previous PR #22770. we try to fix incorrect nullable in target table.
However we changed nullable info of column in source table unexpectly

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

@@ -17,6 +17,7 @@
 
 package org.apache.doris.analysis;
 
+import org.apache.doris.catalog.Column;
 import org.apache.doris.common.ErrorCode;
 import org.apache.doris.common.ErrorReport;
 import org.apache.doris.common.UserException;
@@ -78,8 +79,9 @@ public void analyze(Analyzer analyzer) throws UserException {
         Preconditions.checkArgument(outputs.size() == queryStmt.getResultExprs().size());
         for (int i = 0; i < outputs.size(); ++i) {
             if (queryStmt.getResultExprs().get(i).getSrcSlotRef() != null) {
-                queryStmt.getResultExprs().get(i).getSrcSlotRef().getColumn()
-                        .setIsAllowNull(outputs.get(i).isNullable());
+                Column columnCopy =  new Column(queryStmt.getResultExprs().get(i).getSrcSlotRef().getColumn());
+                columnCopy.setIsAllowNull(outputs.get(i).isNullable());
+                queryStmt.getResultExprs().get(i).getSrcSlotRef().getDesc().setColumn(columnCopy);
             }
         }
         ArrayList<Expr> resultExprs = getQueryStmt().getResultExprs();

regression-test/suites/ddl_p0/test_ctas.groovy

@@ -228,10 +228,14 @@ suite("test_ctas") {
         sql 'insert into a values(1, \'ww\'), (2, \'zs\');'
         sql 'insert into b values(1, 22);'
 
-        sql 'create table c properties("replication_num"="1") as select a.id, a.name, b.age from a left join b on a.id = b.id;'
+        sql 'set enable_nereids_planner=false'
+
+        sql 'create table c properties("replication_num"="1") as select b.id, a.name, b.age from a left join b on a.id = b.id;'
 
-        String desc = sql 'desc c'
-        assertTrue(desc.contains('Yes'))
+        String descC = sql 'desc c'
+        assertTrue(descC.contains('Yes'))
+        String descB = sql 'desc b'
+        assertTrue(descB.contains('No'))
     } finally {
         sql 'drop table a'
         sql 'drop table b'