一、数据类型表
二、常用的两种类型转换方式
select cast('5' as int),cast('2023-06-25' as date);
select cast(department_id as varchar),department_name from dept;
select '5'::int,'2023-06-25'::date;
select department_id::varchar,department_name from dept;
三、常用的转换函数及操作符
布尔类型操作符：https://xiaosonggong.blog.csdn.net/article/details/131416704
数学函数及操作符：https://xiaosonggong.blog.csdn.net/article/details/131416741
字符串函数及操作符：https://blog.csdn.net/songyundong1993/article/details/131416803?spm=1001.2014.3001.5501