摘要:mysql数据库迁移greenplum讲解如下
1.
locate(a,b)->position(a in b)
2.convert()函数不可以使用
3.
ifnull(null,0.00)->COALESCE(null,0.00)
4.
timestampadd(hour,24,jysj)->jysj::timestamp+'24 hour'
5.
substr()->substring()
6.
from_unixtime(unix_timestamp(jysj,'yyyy-MM-dd'))->to_date(jysj,'yyyy-MM-dd')
7.
year(jysj)->to_char(jysj,'yyyy')
8.
concat(cast(cast(nf as char),'年',jd))->nf||'年'||jd as name
9.
substr(from_unix_timestamp(jysj),1,$sjd$)->substring(jysj,1,$sjd$)
10.
instr(a,b)->position(a in b)
11.
if(a=0,1,2)->case when a=0 then 1 else 2 end
12.
if(isnull(jyye),0,jyye)->case jyye when colaesce()
13.
isnull(null,0.00)->COALESCE(null,0.00)jyye then 0 else jyye end as jyye
14.
date_format(jysj,'%y-%m-%d')->to_date(jysj,'yyyy-MM-dd')
15.
left(jyzjhm,4)->substring(jyzjhm from 0 for 4)
16.日期函数 字符串函数
18.insertselect 对于select中的字段有顺序要求,且字段不可以少,必须对应。
19.unix_timestamp(不带引号)->to_timestamp(不带引号)
20.postgresql中没有四舍五入->可以使用cast(a as numeric)来替代round()
21.
data_format(jysj,'%Y-%m')->to_date(jysj,'yyyy-MM')
22.
date_add(jysj,interval 1 day) ->jysj + interval '1 day'
23.
abs(round(unix_stamp(a.jysj)-unix_timestamp(b.jysj))) <$max_sjc$-> a.jysj>b.jysj and b.jysj + interval '$max_sjc$ second' < a.jysj
24.
isnull(a)->a is null
25.
(@rownum:=@rownum+1) -> row_number() over (order by jzje)
26.
if(@pjyhm=t2,@rank:=@rank+1,@rank:=1)->row_number() over(partition by t1.jyhm order by t1.交易总金额 desc)
27.
if(@pjyhm=t2.jymc,@rank:=@rank+1,@rank:=1)->row_number() over (partition by t1.jyhm order by t1.$pxfs$ desc)
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