- 连接字符串
select concat(1,'a',2,'b') from dual //1a2b
- 从字段左侧截取N个字符
select left('abcde',3) from dual //abc
- 从字段右侧截取N个字符
select right('abcde',3) from dual //cde
- 查看字段的字符个数
select length('abcde') from dual //5
- 将日期格式化为字符串
select date_format(curdate(),'%Y-%m-%d') from dual //2021-01-29
- 将小数转换为保留小数点后N位的小数
cast(1.123 as decimal(5,4)) //1.1230
- 查看字符N在字符串中的索引
select instr('abcde','d') from dual //4
- 从指定位置开始截取字符串
select substr('abc',2) from dual //bc
- 从指定字符开始截取字符串
select substr('1.23456',instr('1.23456','.')+1) from dual //23456
- 将字符串反转
select reverse('abcde') from dual //edcba
