fix(query): panic if explaining complex joins (#18538)

Author: dqhl76

src/query/service/src/interpreters/interpreter_explain.rs

@@ -625,7 +625,7 @@ impl ExplainInterpreter {
             return Ok(None);
         }
         let meta = metadata.read();
-        let table_entry = meta.table(source.scan_id);
+        let table_entry = meta.table(source.table_index);
         if let Some(fuse_table) = table_entry.table().as_any().downcast_ref::<FuseTable>() {
             let mut dummy_pipeline = Pipeline::create();
             let prune_pipeline = fuse_table.do_build_prune_pipeline(

tests/sqllogictests/suites/ydb/select1-1.test

@@ -1589,6 +1589,20 @@ order by col2,col6,col3,col5,col4,col1
 222 0 -1 240 28 723
 444 0 2 249 29 743
 
+# issues: https://github.com/databendlabs/databend/issues/18536
+statement ok
+explain SELECT CASE a+1 WHEN b THEN 111 WHEN c THEN 222
+          WHEN d THEN 333  WHEN e THEN 444 ELSE 555 END AS col1,
+         (SELECT COUNT(*) FROM t1 AS x WHERE x.c>t1.c AND x.d<t1.d) AS col2,
+         d-e AS col3,
+         b AS col4,
+         (SELECT COUNT(*) FROM t1 AS x WHERE x.b<t1.b) AS col5,
+         a+b*2 AS col6
+  FROM t1
+  WHERE EXISTS(SELECT 1 FROM t1 AS x WHERE x.b<t1.b)
+      OR (a>b-2 AND a<b+2)
+  ORDER BY col2,col6,col3,col5,col4,col1
+
 query III
 select a as col1,
        c-d as col2,