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,
    "table": {
      "table_name": "t1",
      "access_type": "ALL",
      "rows": 2,
      "filtered": 100
    },
    "subqueries": [
      {
        "query_block": {
          "select_id": 2,
          "table": {
            "table_name": "tbl_alias1",
            "access_type": "ALL",
            "rows": 1,
            "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": "9",
            "used_key_parts": ["c", "b"],
            "ref": [
              "test.tbl_alias1.column_name_2",
              "test.tbl_alias1.column_name_1"
            ],
            "rows": 1,
            "filtered": 100,
            "attached_condition": "(tbl_alias2.c = tbl_alias1.column_name_2)",
            "using_index": true
          }
        }
      }
    ]
  }
}
drop table t1,t2,t3;