GaussDB(DWS)中Oracle不兼容语法修改集
1、递归语法
- 单表递归
Oracle:
create table tb_recursive(id int,parent_id int); insert into tb_recursive values(0,''); insert into tb_recursive values(1,0); insert into tb_recursive values(11,1); insert into tb_recursive values(12,1); insert into tb_recursive values(111,11); insert into tb_recursive values(2,0); insert into tb_recursive values(21,2); insert into tb_recursive values(22,2); insert into tb_recursive values(222,22); insert into tb_recursive values(211,21); insert into tb_recursive values(212,21); select id,parent_id,level lvl from tb_recursive connect by prior id=parent_id start with parent_id is null order by id; |
Gauss:
create table tb_recursive(id int,parent_id int); insert into tb_recursive values(0,''); insert into tb_recursive values(1,0); insert into tb_recursive values(11,1); insert into tb_recursive values(12,1); insert into tb_recursive values(111,11); insert into tb_recursive values(2,0); insert into tb_recursive values(21,2); insert into tb_recursive values(22,2); insert into tb_recursive values(222,22); insert into tb_recursive values(211,21); insert into tb_recursive values(212,21); with recursive r1 as ( select id,parent_id,1 as lvl from tb_recursive where parent_id is null union all select t.id,t.parent_id,t1.lvl+1 as lvl from tb_recursive t,r1 t1 where t.parent_id=t1.id) select id,parent_id,lvl from r1 order by id; |
Oracle:
select id,parent_id,level lvl from tb_recursive connect by id=prior parent_id start with parent_id is null order by id; |
Gauss:
with recursive r1 as ( select id,parent_id,1 as lvl from tb_recursive where parent_id is null union all select t.id,t.parent_id,t1.lvl+1 as lvl from tb_recursive t,r1 t1 where t.id=t1.parent_id) select id,parent_id,lvl from r1 order by id; |
- sys_connect_by_path
Oracle:
select id,parent_id,sys_connect_by_path(id,' > ') path,level lvl from tb_recursive connect by prior id= parent_id start with parent_id is null order by id; |
Gauss:
with recursive r1 as ( select id,parent_id,' > '||id path,1 as lvl from tb_recursive where parent_id is null union all select t.id,t.parent_id,t1.path||' > '||t.id path,t1.lvl+1 as lvl from tb_recursive t,r1 t1 where t.parent_id=t1.id) select id,parent_id,path,lvl from r1 order by id; |
- order siblings by
Oracle:
select id,parent_id,level lvl from tb_recursive connect by prior id=parent_id start with parent_id is null order siblings by id; |
Gauss:
with recursive r1 as ( select id,parent_id,1 as lvl,lpad(id,4,0)||lpad(ctid||xc_node_id::text,20,0) sortno from tb_recursive where parent_id is null union all select t.id,t.parent_id,t1.lvl+1 as lvl,t1.sortno||lpad(t.id,4,0)||lpad(ctid||xc_node_id::text,20,0) sortno from tb_recursive t,r1 t1 where t.parent_id=t1.id) select id,parent_id,lvl from r1 order by sortno; |
- connect_by_root
Oracle:
select id,parent_id,connect_by_root(parent_id) as rid,level lvl from tb_recursive connect by prior id=parent_id start with parent_id =2 order by id; |
Gauss:
with recursive r1 as ( select id,parent_id,parent_id rid,1 as lvl from tb_recursive where parent_id =2 union all select t.id,t.parent_id,t1.rid,t1.lvl+1 as lvl from tb_recursive t,r1 t1 where t.parent_id=t1.id) select id,parent_id,rid,lvl from r1 order by id; |
- connect by前有where
Oracle:
select id,parent_id,level lvl from tb_recursive where parent_id = 1 connect by prior id=parent_id start with parent_id is null order by id; |
Gauss:
with recursive r1 as ( select id,parent_id,1 as lvl from tb_recursive where parent_id is null union all select t.id,t.parent_id,t1.lvl+1 as lvl from tb_recursive t,r1 t1 where t.parent_id=t1.id) select id,parent_id,lvl from r1 where parent_id =1 order by id; |
2、Rownum
- select list中
Oracle:
select id,parent_id,rownum from tb_recursive order by 3; |
Gauss:
select id,parent_id,row_number() over() from tb_recursive order by 3; |
- where条件中
Oracle:
select id,parent_id from tb_recursive where rownum =1 order by id; |
Gauss:
select id,parent_id from tb_recursive order by id limit 1; |
- sql语句中有order by
Oracle:
select id from (select id,parent_id from tb_recursive order by id desc) where rownum =1; |
Gauss:
select id from tb_recursive order by id desc limit 1; |
- sql语句中有count
Oracle:
select count(1) from (select id,parent_id from tb_recursive where id = 1) where rownum =1; |
Gauss:
select count(1) from (select id,parent_id from tb_recursive where id = 1 limit 1); |
- sql语句中有max/min
Oracle:
select max(id) from tb_recursive where parent_id=21 and rownum =1; select min(id) from tb_recursive where parent_id=21 and rownum =1; |
Gauss:
select id from tb_recursive where parent_id=21 order by id limit 1; |
3、Max/Min...keep语法
- 单表max,dense_rank last
Oracle:
select max(id) keep (dense_rank last order by parent_id) from tb_recursive; |
Gauss:
select id from tb_recursive order by parent_id desc,id desc limit 1; |
- 单表max,dense_rank first
Oracle:
select max(id) keep (dense_rank first order by parent_id) from tb_recursive; |
Gauss:
select id from tb_recursive order by parent_id asc,id desc limit 1; |
- 单表min,dense_rank last
Oracle:
select min(id) keep (dense_rank last order by parent_id) from tb_recursive; |
Gauss:
select id from tb_recursive order by parent_id desc,id asc limit 1; |
- 单表min,dense_rank first
Oracle:
select min(id) keep (dense_rank first order by parent_id) from tb_recursive; |
Gauss:
select id from tb_recursive order by parent_id asc,id asc limit 1; |
4、pivot语法
测试表及数据:
drop table if exists tb_test;
create table tb_test(a int,b int);
insert into tb_test values(1,1),(1,1),(1,2),(1,3),(1,4),(2,1),(2,2),(2,3),(2,2),(2,4),(2,5),(2,6);
Oracle:
select * from (select a,b,count(*) cnt from tb_test group by a,b) t pivot (sum(cnt) for a in (1 c,2 d,3 e,4 f)); |
Gauss:
select b,sum(case a when 1 then cnt end) C, sum(case a when 2 then cnt end) D, sum(case a when 3 then cnt end) E, sum(case a when 4 then cnt end) F from (select a,b,count(*) cnt from tb_test group by a,b) group by b; |
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