mysql、clickhouse查询数据库所有的表以及字段信息

mysql查询数据库所有的表以及字段信息

SELECT
    table_schema 数据库名,
  table_name 表名,
  COLUMN_NAME 列名,
  COLUMN_TYPE 数据类型,
  DATA_TYPE 字段类型,
  CHARACTER_MAXIMUM_LENGTH 长度,
  IS_NULLABLE 是否为空,
  COLUMN_DEFAULT 默认值,
  COLUMN_COMMENT 备注 
FROM
 INFORMATION_SCHEMA.COLUMNS
where
-- table_schema 为库名
table_schema ='XXX'
AND
-- table_name为表名
table_name  in (SELECT table_name FROM (SELECT table_name, table_comment, create_time, update_time FROM information_schema.tables
WHERE table_schema = (SELECT DATABASE())
ORDER BY create_time DESC) as t )

clickhouse导出表信息

SELECT
    database AS `数据库名`,
    table AS `表名`,
    name AS `列名`,
    type AS `类型`,
    default_expression AS `默认值`,
    numeric_precision AS `数字精度`,
    numeric_scale AS `小数位数`,
    comment AS `字段说明` 
FROM
    system.columns
WHERE
    database='default'