fix(query): forbid explain explain statement

src/query/sql/src/planner/binder/binder.rs

@@ -212,6 +212,9 @@ impl<'a> Binder {
             }
 
             Statement::ExplainAnalyze {partial, graphical, query } => {
+                if let Statement::Explain { .. } | Statement::ExplainAnalyze { .. } = query.as_ref() {
+                    return Err(ErrorCode::SyntaxException("Invalid statement"));
+                }
                 let plan = self.bind_statement(bind_context, query).await?;
                 Plan::ExplainAnalyze { partial: *partial, graphical: *graphical, plan: Box::new(plan) }
             }

src/query/sql/src/planner/binder/explain.rs

@@ -76,6 +76,9 @@ impl Binder {
         inner: &Statement,
     ) -> Result<Plan> {
         let mut builder = ExplainConfigBuilder::new();
+        if let Statement::Explain { .. } | Statement::ExplainAnalyze { .. } = inner {
+            return Err(ErrorCode::SyntaxException("Invalid statement"));
+        }
 
         // Rewrite `EXPLAIN RAW` to `EXPLAIN(LOGICAL)`
         if matches!(kind, ExplainKind::Raw) {

tests/sqllogictests/suites/mode/standalone/explain/explain.test

@@ -10,6 +10,18 @@ create table t1 as select number as a, number as b from numbers(1)
 statement ok
 create table t2 as select number as a, number as b from numbers(5)
 
+statement error 1005
+explain explain select t1.a from t1 where a > 0
+
+statement error 1005
+explain explain analyze select t1.a from t1 where a > 0
+
+statement error 1005
+explain analyze explain select t1.a from t1 where a > 0
+
+statement error 1005
+explain analyze explain analyze select t1.a from t1 where a > 0
+
 query T
 explain select t1.a from t1 where a > 0
 ----