CREATE TABLE test_id (
    ID int,
    PRIMARY KEY (`ID`)
  )
  SELECT * FROM test_id WHERE id=1;

  fix explain NULL able column bug

  +----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+--------------------------------+
  | id | select_type | table | partitions | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra                          |
  +----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+--------------------------------+
  |  1 | SIMPLE      | NULL  | NULL       | NULL | NULL          | NULL | NULL    | NULL | NULL |     NULL | no matching row in const table |
  +----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+--------------------------------+

  sleep(), benchmark(), get_lock, release_lock() are
  dangerous function may not be used in online.

  SHOW TABLE STATUS

  Rows
  AvgRowLength
  DataLENGTH
  MaxDataLength
  IndexLength
  DataFree

* import bats for cli test

  https://github.com/sstephenson/bats

* add simple test case for cli use bats

* format main.bats add env

* replace main_test.sh with main.bats

  make explain suggestion sorted
  make index suggestion sorted

* add test database world_x

* update bats golden result

* make docker add 180s timeout

  1. add timeout for docker start
  2. add not explain able sql test case into explain_test.go

* explain info Using index VS Using index condition

  remove nonappearence key from explain extra info

* add timeout for test

* fix #178  JSON datatype only support utf8mb4 now

* splitstatement support optimizer hint

  https://dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html
  https://dev.mysql.com/doc/refman/8.0/en/comments.html

* vendor daily update

* format explain suggestion content

  1. update vendor
  2. `use db` can't be explain, it will print err log at explain.go

* fix #176

  JSON datatype only support utf8mb4 now

* splitstatement support optimizer hint

  https://dev.mysql.com/doc/refman/8.0/en/optimizer-hints.html
  https://dev.mysql.com/doc/refman/8.0/en/comments.html

* vendor daily update

  JSON datatype only support utf8mb4 now

  compatibly with old version(<0.10.0)

  we change mymysql to go-sql-driver and use insert unhex()
  for any dangerous data type.

  1. remove Index_Comment in ShowIndex function
  2. remove mysql client deps in Makefile

not fix too many connections yet

  go test ./... -update

  COL.015 text/blob default value only tobe `NULL`;
  COL.012 text/blob `NOT NULL` CONSTRAINT may be danagerous;