improve error message on unknown placeholder

Author: r1b

datafusion/sql/src/expr/value.rs

@@ -134,7 +134,7 @@ impl<S: ContextProvider> SqlToRel<'_, S> {
                             format!("${}", pos + 1),
                             param_data_types.get(pos).cloned(),
                         ))),
-                        None => plan_err!("Invalid placeholder: {param}"),
+                        None => plan_err!("Unknown placeholder: {param}"),
                     }
                 };
             }

datafusion/sql/tests/cases/params.rs

@@ -105,7 +105,7 @@ fn test_prepare_statement_to_plan_panic_param_format() {
     assert_snapshot!(
         logical_plan(sql).unwrap_err().strip_backtrace(),
         @r###"
-        Error during planning: Invalid placeholder: $foo
+        Error during planning: Unknown placeholder: $foo
         "###
     );
 }

datafusion/sqllogictest/test_files/prepare.slt

@@ -34,7 +34,7 @@ statement error DataFusion error: SQL error: ParserError
 PREPARE AS SELECT id, age  FROM person WHERE age = $foo;
 
 # param following a non-number, $foo, not supported
-statement error Invalid placeholder: \$foo
+statement error Unknown placeholder: \$foo
 PREPARE my_plan(INT) AS SELECT id, age  FROM person WHERE age = $foo;
 
 # not specify table hence cannot specify columns