Mysql

CREATE TABLE YH  (
    id int PRIMARY KEY COMMENT '主键id',
    name varchar(50) NOT NULL COMMENT '姓名',
    age int COMMENT '年龄'
) COMMENT '用户表';

SELECT
    TABLE_COMMENT AS '表注释',
    TABLE_ROWS AS '表中的行数（估计值）',
    CREATE_TIME AS '表创建时间',
    UPDATE_TIME  AS '表最后修改时间'
FROM
    INFORMATION_SCHEMA.TABLES 
WHERE
    TABLE_SCHEMA = 'test' 
    AND TABLE_NAME = 'YH';

SELECT
    ORDINAL_POSITION AS '序号',
    COLUMN_NAME AS '列名',
    DATA_TYPE AS '类型',
    COLUMN_TYPE AS '详细类型',
    CASE COLUMN_KEY WHEN 'PRI' THEN '主键'    WHEN 'UNI' THEN '唯一索引'    WHEN 'MUL' THEN '非唯一索引' ELSE COLUMN_KEY END AS '索引',
    IS_NULLABLE AS '是否为 NULL',
    COLUMN_COMMENT  AS '注释'
FROM
    INFORMATION_SCHEMA.COLUMNS 
WHERE
    TABLE_SCHEMA = 'test' 
    AND TABLE_NAME = 'YH';