-- 查询一个表共有多少列数
select count(*) 
from information_schema.COLUMNS 
where TABLE_SCHEMA=‘库名‘ and table_name=‘表名‘ 

-- 查询某个数据库中某个表的所有列名
SELECT COLUMN_NAME FROM information_schema.COLUMNS
WHERE TABLE_SCHEMA = ‘db_name‘ AND TABLE_NAME = ‘tb_name‘;

-- 查询某个数据库中某个表的所有列名,并用逗号连接
SELECT GROUP_CONCAT(COLUMN_NAME SEPARATOR ",") FROM information_schema.COLUMNS 
WHERE TABLE_SCHEMA = ‘db_name‘ AND TABLE_NAME = ‘tb_name‘;