Oracle 到 MySQL 函数替换方案汇总

常用函数和语法转换

 

 

NVL函数

• Oracle语法: NVL(COUNT(*), 0)
• MySQL语法: IFNULL(COUNT(*), 0)

 

转字符串

• Oracle语法: to_char(字段)
• MySQL语法: CONVERT(字段, CHAR)

 

Rownum递增

• Oracle语法: SELECT rownum num FROM SYS_ENUM
• MySQL语法: SELECT (@i:=@i+1) num FROM sys_enum, (SELECT @i:=0) AS it

 

Delete增加表别名

• Oracle语法: DELETE from sys_menus s WHERE s.MENU_ID in (86,87,88);
• MySQL语法: DELETE s from sys_menus s WHERE s.MENU_ID in (86,87,88);

 

日期和字符转换

• Oracle语法: to_char(), to_date();
• MySQL语法: DATE_FORMAT(date, '%Y-%m-%d'), STR_TO_DATE(date, '%Y-%m-%d %H:%i:%s')

 

UUID

• Oracle语法: sys_guid()
• MySQL语法: REPLACE(UUID(), _utf8'-', _utf8'')

 

特殊字符转换

• Oracle语法: to_char(SALARY_NUM, 'fm99999999999990.00')
• MySQL语法: CONVERT(FORMAT(SALARY_NUM, 2), CHAR)

 

按拼音首字母排序

• Oracle语法: nlssort(enterprise_name, 'NLS_SORT=SCHINESE_PINYIN_M')
• MySQL语法: convert(name using gbk) ASC

 

Trunc函数截取月初

• Oracle语法: trunc(sysdate, 'yyyy-MM-dd'), 'mm')
• MySQL语法: DATE_ADD(sysdate(), INTERVAL -DAY(sysdate()) +1 DAY)

 

Trunc函数

• Oracle语法: trunc(sysdate)
• MySQL语法: SELECT STR_TO_DATE(DATE_FORMAT(SYSDATE(), '%Y%m%d'), '%Y%m%d%H')

 

Rownum日期操作

• Oracle语法: sysdate-1
• MySQL语法: set @dt =SYSDATE(); select date_add(@dt, interval 1 day) from dual;

 

Decode

• Oracle语法: DECODE(t.CARD_STATUS, 1, '01', 6, '06', 2, '02', 4, '04', null) as CWR_CARD_STATUS
• MySQL语法: (CASE WHEN t.CARD_STATUS = 1 THEN '01' WHEN t.CARD_STATUS = 6 THEN '06' WHEN t.CARD_STATUS = 2 THEN '02' WHEN t.CARD_STATUS = 4 THEN '04' ELSE null END) as CWR_CARD_STATUS

 

Nulls Last

• Oracle语法: nulls last
• MySQL语法: order by IF(ISNULL(my_field), 1, 0), my_field;

 

Nulls First

• Oracle语法: nulls first
• MySQL语法: order by IF(ISNULL(my_field), 0, 1), my_field;

 

To_char（数字格式化）

• Oracle语法: to_char（数据, 'FM9999990.00'）
• MySQL语法: format(数据, 2)

 

Merge Into

• Oracle语法: merge into
• MySQL语法: `-- 修改成UPDATE 和 INSERT

 

文本拼接

• Oracle语法: ||
• MySQL语法: CONCAT('1','2''3')

 

substr

• 注意: MySQL中不能将0作为起始点，需要改成1。

 

时间的计算

• Oracle语法: 可以直接相减（默认单位：天）
• MySQL语法:使用 TIMESTAMPDIFF（需指定默认单位）

row number over

• Oracle语法:

SELECT a.*,
ROW_NUMBER() OVER(partition by a.orderchildId order by a.CheckEndTime desc) as rum_num
FROM biz_qa_check_first a

• MySQL语法:

select @rownum:=@rownum+1 rownum,a.*,
if(@orderchildId=a.orderchildId,@rank:=@rank+1,@rank:=1) as rum_num,
@orderchildId:=a.orderchildId
from(SELECT * from biz_qa_check_first order by orderchildId,CheckEndTimedesc)a,
(select @rownum:=0,@orderchildId:=null,@rank:=0)b