MySQL与Oracle常用函数

• 日期转字符串

// Oracle
to_char(sysdate,'yyyy-MM-dd HH24:mm:ss')

// MySQL
select date_format(now(),'%Y-%m-%d %H:%i:%s')

• 数字转字符串

//Oracle
to_char(1)

//MySQL
select cast(number as char)  / select cast(123 as char)
select concat(123,'')

• 字符串转数字

//Oracle
to_number(sort)

//MySQL
cast(sort as signed integer)

• 2个字符串返回一个非空的 (NULL)

//Oracle
select NVL(expr1,expr2)

//MySQL
select ifnull(expr1,expr2)