drop table if exists t0,t1,t2;
#
# MDEV-7266: Assertion `!element_started' failed in Json_writer& Json_writer::add_member
# 
CREATE TABLE t1 (a INT) ENGINE=InnoDB;
INSERT INTO t1 VALUES (1),(2);
CREATE TABLE t2 (column_name_1 INT, column_name_2 VARCHAR(52)) ENGINE=InnoDB;
INSERT INTO t2 VALUES (3,'United States');
CREATE TABLE t3 (b INT, c VARCHAR(3), PRIMARY KEY (c,b)) ENGINE=InnoDB;
INSERT INTO t3 VALUES (4,'USA'),(5,'CAN');
EXPLAIN FORMAT=JSON SELECT * FROM t1 WHERE 0 < ALL ( 
SELECT tbl_alias1.column_name_1 FROM t2 AS tbl_alias1, t3 AS tbl_alias2 
WHERE tbl_alias2.b = tbl_alias1.column_name_1 AND tbl_alias2.c = tbl_alias1.column_name_2 
);
EXPLAIN
{
  "query_block": {
    "select_id": 1,
    "cost": "COST_REPLACED",
    "nested_loop": [
      {
        "table": {
          "table_name": "t1",
          "access_type": "ALL",
          "loops": 1,
          "rows": 2,
          "cost": "COST_REPLACED",
          "filtered": 100
        }
      }
    ],
    "subqueries": [
      {
        "query_block": {
          "select_id": 2,
          "cost": "COST_REPLACED",
          "nested_loop": [
            {
              "table": {
                "table_name": "tbl_alias1",
                "access_type": "ALL",
                "loops": 1,
                "rows": 1,
                "cost": "COST_REPLACED",
                "filtered": 100,
                "attached_condition": "tbl_alias1.column_name_2 is not null and tbl_alias1.column_name_1 is not null"
              }
            },
            {
              "table": {
                "table_name": "tbl_alias2",
                "access_type": "eq_ref",
                "possible_keys": ["PRIMARY"],
                "key": "PRIMARY",
                "key_length": "18",
                "used_key_parts": ["c", "b"],
                "ref": [
                  "test.tbl_alias1.column_name_2",
                  "test.tbl_alias1.column_name_1"
                ],
                "loops": 1,
                "rows": 1,
                "cost": "COST_REPLACED",
                "filtered": 100,
                "attached_condition": "tbl_alias2.c = tbl_alias1.column_name_2"
              }
            }
          ]
        }
      }
    ]
  }
}
drop table t1,t2,t3;