GaussDB: db2->gaussdb 函数转换

一、db2->gaussdb函数转换

问题描述：使用GaussDB替代DB2的方案，使用起来还是有些差别，做一下函数的映射转换。

	DB2写法	GaussDB改写语法
日期函数	days(OUTWORKDATE)	EXTRACT(epoch from outworkdate) /86400; EXTRACT(DAY FROM (OUTWORKDATE - DATE '0001-01-01' + INTEGER '1' ))
	day(OUTWORKDATE)	EXTRACT(DAY FROM outworkdate); DATE_PART('DAY', OUTWORKDATE)
	month(current_date)	EXTRACT(MONTH FROM current_date); DATE_PART('MONTH', TRUNC(CURRENT_DATE))
	year(current_date)	EXTRACT(YEAR FROM outworkdate); DATE_PART('YEAR', TRUNC(CURRENT_DATE))
	CURRENT_DATE -1 DAY/MONTH/YEAR	CURRENT_DATE - INTERVAL '1 day' AS yesterday, CURRENT_DATE - INTERVAL '1 month' AS last_month, CURRENT_DATE - INTERVAL '1 year' AS last_year; TRUNC(CURRENT_DATE) - INTERVAL '1 DAY' AS yesterday, TRUNC(CURRENT_DATE) - INTERVAL '1 MONTH' AS last_month, TRUNC(CURRENT_DATE) - INTERVAL '1 YEAR' AS last_year;
	CURRENT_DATE -1 DAY -1 MONTH	current_date - interval '1 DAY' - interval '1 MONTH'
	to_char(CURRENT_DATE,'yyyy-mm')	to_char(current_date,'yyyy-mm');to_char(trunc(current_date),'yyyy-mm')
	TIMESTAMPDIFF(2,END_TIME - START_TIME)	extract(epoch from (end_time - start_time)); trunc(extract(epoch from (end_time - start_time))); TIMESTAMPDIFF()函数只在mysql模式中可以使用
数据类型转化	dec(RATE,10,2)	rate::numeric(10,2); cast(rate as numeric(10,2));
	int(100.123)	cast(100.123 as int); 100.123::int;
	char(1)	cast(1 as char(1))
	to_date()	to_date()
	to_char()	to_char()
其他常用函数	LOCATE('\|','115\|56',1)	INSTR('115\|56', '\|', 1)
	listagg(name,',')	listagg(b,';') within group (order by b)
	nvl()	nvl()
	trim()	trim(BOTH 'x' from 'xTommxx'); trim(leading 'x' from 'xTommxx'); trim(trailing 'x' from 'xTommxx');
	substr()	substr('stringtest' from 4); substr('stringtest',4);
	VALUE()	COALESCE()
	floor()	floor()
	round()	round()
	coalesce(company,0)	coalesce(company,0)
	length()	length()
	POSSTR(EXP1,EXP2)	position(exp1,exp2)
	REPLACE (EXP1,EXP2,EXP3)	replace(exp1,exp2,exp3)

二、测试过程

日期函数

days(outworkdate) 函数转换*****************************************************************************

create table employee(id serial primary key,name varchar(100),outworkdate date);

insert into employee(name,outworkdate) values('alice','2023-01-15');

insert into employee(name,outworkdate) values('bob','2023-02-20');

insert into employee(name,outworkdate) values('david','2023-04-05');

insert into employee(name,outworkdate) values('eve','2023-05-25');

testdb_0903=> select name,outworkdate,extract(epoch from outworkdate) / 86400 as days_since_epoch from employee;

 name  |     outworkdate     | days_since_epoch

-------+---------------------+------------------

 alice | 2023-01-15 00:00:00 |            19372

 bob   | 2023-02-20 00:00:00 |            19408

 david | 2023-04-05 00:00:00 |            19452

 eve   | 2023-05-25 00:00:00 |            19502

(4 rows)

testdb_0903=> select name,outworkdate,extract(day from (outworkdate-date '1970-01-01'+integer '1'))  as days_since_epoch from employee;

 name  |     outworkdate     | days_since_epoch

-------+---------------------+------------------

 alice | 2023-01-15 00:00:00 |            19373

 bob   | 2023-02-20 00:00:00 |            19409

 david | 2023-04-05 00:00:00 |            19453

 eve   | 2023-05-25 00:00:00 |            19503

(4 rows)

day(outworkdate) 函数转换*****************************************************************************

testdb_0903=> select name,outworkdate,extract(day from outworkdate)  as day_of_month from employee;

 name  |     outworkdate     | day_of_month

-------+---------------------+--------------

 alice | 2023-01-15 00:00:00 |           15

 bob   | 2023-02-20 00:00:00 |           20

 david | 2023-04-05 00:00:00 |            5

 eve   | 2023-05-25 00:00:00 |           25

(4 rows)

testdb_0903=>

testdb_0903=>

testdb_0903=> select name,outworkdate,date_part('DAY',outworkdate) as day_of_month from employee;

 name  |     outworkdate     | day_of_month

-------+---------------------+--------------

 alice | 2023-01-15 00:00:00 |           15

 bob   | 2023-02-20 00:00:00 |           20

 david | 2023-04-05 00:00:00 |            5

 eve   | 2023-05-25 00:00:00 |           25

(4 rows)

month(current_date) 函数转换*****************************************************************************

testdb_0903=> select extract(month from current_date) from dual;

 date_part

-----------

         9

(1 row)

testdb_0903=> select date_part('MONTH',trunc(current_date)) from dual;

 date_part

-----------

         9

(1 row)

year(current_date) 函数转换*****************************************************************************

testdb_0903=> select extract(year from current_date) from dual;

 date_part

-----------

      2024

(1 row)

testdb_0903=>

testdb_0903=> select date_part('YEAR',trunc(current_date)) from dual;

 date_part

-----------

      2024

(1 row)

current_date -1 DAY/MONTH/YEAR 函数转换*****************************************************************************

testdb_0903=> select current_date as today,

current_date - interval '1 day' as yesterday,

current_date - interval '1 month' as last_month,

current_date - interval '1 year' as last_year from dual;

   today    |      yesterday      |     last_month      |      last_year

------------+---------------------+---------------------+---------------------

 2024-09-29 | 2024-09-28 00:00:00 | 2024-08-29 00:00:00 | 2023-09-29 00:00:00

(1 row)

testdb_0903=>

testdb_0903=> select trunc(current_date) - interval '1 DAY' as yesterday,

trunc(current_date) - interval '1 month' as last_month,

trunc(current_date) - interval '1 year' as last_year from dual;

      yesterday      |     last_month      |      last_year

---------------------+---------------------+---------------------

 2024-09-28 00:00:00 | 2024-08-29 00:00:00 | 2023-09-29 00:00:00

(1 row)

current_date -1 DAY -1 MONTH 函数转换*****************************************************************************

testdb_0903=> select current_date - interval '1 DAY' - interval '1 MONTH' as result_date from dual;

     result_date

---------------------

 2024-08-28 00:00:00

(1 row)

testdb_0903=>

testdb_0903=> select trunc(current_date) - interval '1 DAY' - interval '1 MONTH' as result_date from dual;

     result_date

---------------------

 2024-08-28 00:00:00

(1 row)

to_char(current_date,'yyyy-mm') 函数转换*****************************************************************************

testdb_0903=> select to_char(current_date,'yyyy-mm') from dual;

 to_char

---------

 2024-09

(1 row)

testdb_0903=> select to_char(trunc(current_date),'yyyy-mm') from dual;

 to_char

---------

 2024-09

(1 row)

timestampdiff(2,end_time-start_time) 函数转换*****************************************************************************

GaussDB同名函数仅在MySQL模式数据库中有效。

testdb_0903=> create table events(id serial primary key,start_time timestamp,end_time timestamp);

testdb_0903=> insert into events(start_time,end_time) values('2023-10-01 10:00:00','2023-10-01 10:30:00');

testdb_0903=> insert into events(start_time,end_time) values('2023-10-01 11:00:00','2023-10-01 12:15:00');

testdb_0903=> insert into events(start_time,end_time) values('2023-10-01 13:00:00','2023-10-01 13:45:00');

testdb_0903=> select id,start_time,end_time,extract(epoch from (end_time - start_time))  as diff_time from events;

 id |     start_time      |      end_time       | diff_time

----+---------------------+---------------------+-----------

  1 | 2023-10-01 10:00:00 | 2023-10-01 10:30:00 |      1800

  2 | 2023-10-01 11:00:00 | 2023-10-01 12:15:00 |      4500

  3 | 2023-10-01 13:00:00 | 2023-10-01 13:45:00 |      2700

(3 rows)

testdb_0903=>

testdb_0903=> select id,start_time,end_time,trunc(extract(epoch from (end_time - start_time))) as diff_time from events;

 id |     start_time      |      end_time       | diff_time

----+---------------------+---------------------+-----------

  1 | 2023-10-01 10:00:00 | 2023-10-01 10:30:00 |      1800

  2 | 2023-10-01 11:00:00 | 2023-10-01 12:15:00 |      4500

  3 | 2023-10-01 13:00:00 | 2023-10-01 13:45:00 |      2700

(3 rows)

数据类型转化

dec(RATE,10,2) 函数转换*****************************************************************************

create table sales(id serial primary key,rate float);

insert into sales(rate) values(123.456),(789.123456),(456.789),(12.3),(0.987654);

testdb_0903=> select id,rate,rate::numeric(10,2) as formatted_rate from sales;

 id |        rate         | formatted_rate

----+---------------------+----------------

  1 | 123.456000000000003 |         123.46

  2 | 789.123456000000033 |         789.12

  3 | 456.788999999999987 |         456.79

  4 | 12.3000000000000007 |          12.30

  5 | .987654000000000032 |            .99

(5 rows)

testdb_0903=>

testdb_0903=>

testdb_0903=> select id,rate,cast(rate as numeric(10,2)) as formatted_rate from sales;

 id |        rate         | formatted_rate

----+---------------------+----------------

  1 | 123.456000000000003 |         123.46

  2 | 789.123456000000033 |         789.12

  3 | 456.788999999999987 |         456.79

  4 | 12.3000000000000007 |          12.30

  5 | .987654000000000032 |            .99

(5 rows)

int(100.123) 函数转换*****************************************************************************

testdb_0903=> select cast(100.123 as int) as int_value from dual;

 int_value

-----------

       100

(1 row)

testdb_0903=>

testdb_0903=> select 100.123::int as int_values from dual;

 int_values

------------

        100

(1 row)

char(1) 函数转换*****************************************************************************

testdb_0903=> select cast(1 as char(1)) as char_value;

 char_value

------------

 1

(1 row)

to_char(1) 函数转换*****************************************************************************

testdb_0903=> select to_char(current_timestamp,'HH12:MI:SS');

 to_char

----------

 10:14:46

(1 row)

testdb_0903=> select to_char(125.8::real,'999D99');

 to_char

---------

  125.80

(1 row)

to_date(1) 函数转换*****************************************************************************

testdb_0903=> select to_date('2024-09-30');

       to_date

---------------------

 2024-09-30 00:00:00

(1 row)

testdb_0903=> select to_date('05 Dec 2000','DD Mon YYYY');

       to_date

---------------------

 2000-12-05 00:00:00

(1 row)

其它常用函数转换

locate('|','115|56',1) 函数转换*****************************************************************************

testdb_0903=> select instr('115|56','|',1) as position from dual;

 position

----------

        4

(1 row)

listagg(name,',') 函数转换*****************************************************************************

testdb_0903=> create table listagg_t1(a int,b text);

testdb_0903=> insert into listagg_t1 values(null,'a1'),(1,'b2'),(1,'c3'),(2,'d4'),(2,'e5'),(3,'f6');

testdb_0903=> select a,listagg(b,';') within group (order by b)  from listagg_t1 group by 1;

 a | listagg

---+---------

 1 | b2;c3

 2 | d4;e5

 3 | f6

   | a1

(4 rows)

nvl() 函数转换*****************************************************************************

testdb_0903=> select nvl(null,1);

 nvl

-----

 1

(1 row)

testdb_0903=>

testdb_0903=> select nvl('Hello world',1);

     nvl

-------------

 Hello world

(1 row)

trim() 函数转换*****************************************************************************

testdb_0903=> select trim(BOTH 'x' from 'xTommxx');

 btrim

-------

 Tomm

(1 row)

testdb_0903=> select trim(leading 'x' from 'xTommxx');

 ltrim

--------

 Tommxx

(1 row)

testdb_0903=> select trim(trailing 'x' from 'xTommxx');

 rtrim

-------

 xTomm

(1 row)

substr() 函数转换*****************************************************************************

testdb_0903=>

testdb_0903=> select substr('stringtest' from 4);

 substr

---------

 ingtest

(1 row)

testdb_0903=> select substr('stringtest',4);

 substr

---------

 ingtest

(1 row)

testdb_0903=>

testdb_0903=> select substr('teststring' from 5 for 2);

 substr

--------

 st

(1 row)

testdb_0903=> select substr('string',2,3);

 substr

--------

 tri

(1 row)

value() 函数转换*****************************************************************************

testdb_0903=> select coalesce(null,'hello');

 coalesce

----------

 hello

(1 row)

floor() 函数转换*****************************************************************************

testdb_0903=> select floor(-42.8);

 floor

-------

   -43

(1 row)

round() 函数转换*****************************************************************************

testdb_0903=> select round(42.4);

 round

-------

    42

(1 row)

coalesce() 函数转换*****************************************************************************

testdb_0903=> select coalesce(null,'hello');

 coalesce

----------

 hello

(1 row)

length() 函数转换*****************************************************************************

testdb_0903=> select length('abcd');

 length

--------

      4

(1 row)

testdb_0903=>

testdb_0903=> select length('汉字abc');

 length

--------

      5

(1 row)

posstr(exp1,exp2) 函数转换*****************************************************************************

testdb_0903=> select position('World' in 'Hello World') as pos;

 pos

-----

   7

(1 row)

replace() 函数转换*****************************************************************************

testdb_0903=> select replace('abcdefabcdef','cd','XXX');

    replace

----------------

 abXXXefabXXXef

(1 row)

testdb_0903=> select replace('abcdefabcdef','cd');

 replace

----------

 abefabef

(1 row)

GaussDB: db2->gaussdb 函数转换的更多相关文章

DB2时间函数实现时间加减
时间加减:后边记得跟上时间类型如day.HOUR TIMESTAMP ( TIMESTAMP(DEF_TIME)+1 day)+18 HOUR DB2时间函数是我们最常见的函数之一,下面就为您介绍 ...
SQLserver中用convert函数转换日期格式
SQLserver中用convert函数转换日期格式 2008-01-23 15:47 SQLserver中用convert函数转换日期格式2008-01-15 15:51SQLserver中用con ...
DB 查询分析器方便地创建DB2自定义函数
DB 查询分析器方便地创建DB2自定义函数马根峰 (广东联合电子服务股份有限公司, 广州 510300) 摘要 ...
db2 OLAP函数使用
说起 DB2 在线分析处理,可以用很好很强大来形容.这项功能特别适用于各种统计查询,这些查询用通常的SQL很难实现,或者根本就无发实现.首先,我们从一个简单的例子开始,来一步一步揭开它神秘的面纱,请看 ...
DB2 OLAP函数的使用
说起 DB2 在线分析处理,可以用很好很强大来形容.这项功能特别适用于各种统计查询,这些查询用通常的SQL很难实现,或者根本就无发实现.首先,我们从一个简单的例子开始,来一步一步揭开它神秘的面纱,请看 ...
如何将DB2的数据库转换到mySQL中？
经过几次尝试最终找到解决的办法,因为网上并没有详细说明,所以下面我将详细的步骤记录如下: 1．大前提是你已经安装好DB2服务器和mySQL服务器,现在只是借用Navicat for MySQL这个软 ...
SQLserver中用convert函数转换日期格式(1)
SQLserver中用convert函数转换日期格式2008-01-15 15:51SQLserver中用convert函数转换日期格式 SQL Server中文版的默认的日期字段datetime格式 ...
Oracle的overlaps函数转换其他数据库语法
首先,来介绍一下Oracle的overlaps函数的用法: overlaps函数是用来判断两个时间段是否有重叠的比如说计算 (a,b),(c,d) 就可以写成: select * from dual ...
mysql 时间函数转换
1 NOW() //当前时间 2 SYSDATE() //当前时间 3 CURRENT_TIMESTAMP 4 以'YYYY-MM-DD HH:MM:SS'或YYYYMMDDHHMMSS格式返回当前的 ...
DB2常用函数
1.char函数 char(current date,ISO)--转换成yyyy-mm-dd char(current date,USA)--转换成mm/dd/yyyy char(current ...

随机推荐

国产CPU（兆芯 kx-6640）播放1080p视频效果
前一阵买了一个国产CPU的主机(国产CPU,国产操作系统UOS--零刻LZX迷你主机 , 显卡驱动安装以及屏幕配置),cpu是兆芯 kx-6640,用来播放1080p的视频虽然不是那么丝滑的流畅,但 ...
Vue Vine：带给你全新的 Vue 书写体验！
你好,我是 Kagol,个人公众号:前端开源星球. 上个月和 TinyVue 的小伙伴们一起参加了 VueConf 24 大会,有幸认识沈青川大佬,并了解了他的 Vue Vine 项目,Vue Vin ...
hibernate validation，spring validation自定义参数校验
1.背景在实际开发中,我们除了会使用常用的参数判断,如字符串不为空,最大值,最小值等我们还可以自定义参数校验规则 2.实际生产问题实际生产中同步订单的时候, 假设我们要求订单状态值只能是 -1, ...
JavaScript魔法：在线Excel附件上传与下载的完美解决方案
最新技术资源(建议收藏) https://www.grapecity.com.cn/resources/ 前言在本地使用Excel时,经常会有需要在Excel中添加一些附件文件的需求,例如在Exce ...
centos7安装docker详细教程
一.准备工作 1.系统要求 docker要求centos的内核版本不低于3.10.centos7满足最低内核要求. 检查当前的内核版本 [root@zspc /]# uname -r 3.10.0-1 ...
如何切换git的HEAD分支
git remote set-head origin some_branch
Kubernetes-8：Deployment、DaemonSet、Job、CronJob等各控制器介绍及演示
前文中也都已经提及过k8s都有哪些常用的控制器,本文对这些控制器进行细剖及演示一下 RS与RC与Deployment关联 RC主要作用就是用来确保容器应用副本数保持用户的期望值数目,即如果有pod异常 ...
smiley-http-proxy-servlet 转发https至 http网页访问
转发 https -> http 网页访问正常的smiley-http-proxy-servlet 写法, 可以转发https接口到http,http接口到http,http访问转发至http ...
.NET 8.0 文档管理系统网盘功能的实现
前言大家好,今天推荐一个文档管理系统Dorisoy.Pan. Dorisoy.Pan 是一个基于 .NET 8 和 WebAPI 构建的文档管理系统,它集成了 Autofac.MediatR.JWT ...
mysql vs mongodb
Comments MongoDB 是NoSQL 数据库,适合存JSON格式数据,MySQL是关系型数据库,适合存table格式数据 MongoDB扩展性更好,MySQL支持主从和cluster但是感觉 ...

GaussDB: db2->gaussdb 函数转换

一、db2->gaussdb函数转换

二、测试过程

日期函数

数据类型转化

其它常用函数转换

GaussDB: db2->gaussdb 函数转换的更多相关文章

随机推荐

热门专题