Duplicate selected row in Vertica Database - sql

Question

I have been asked to duplicate a specific row in a table. For this I used a simple SQL statment:
insert into xyz_tablename(x,y) select * from xyz_tablename where x = "something";
However, this statement copies all the row present where x = "something" which is like multipling the selected row by 2.
What I want is to control via counter the number of rows to be duplicated. Is there any function/procedure for this in Vertica?
Now what I have done uptil now:
Studied about function (I have understood this, however I cannot use this for this problem).
Studied about procedures (Have studied, but cannot understand how to make that bash file).
Learnt that there are no for-while loop in vertica.
Anyone can help me with this problem? I hope I am clear. Let me know if I am missing something. Thanks in advance.

Answer 1

Try as below :
create table mystore.xyz_tablename(
x varchar (10)
,y INT
)
;
INSERT INTO mystore.xyz_tablename VALUES('abc' ,1);
INSERT INTO mystore.xyz_tablename VALUES('abc' ,2);
INSERT INTO mystore.xyz_tablename VALUES('abc' ,3);
INSERT INTO mystore.xyz_tablename VALUES('abc' ,4);
INSERT INTO mystore.xyz_tablename VALUES('abc' ,5);
INSERT INTO mystore.xyz_tablename VALUES('abc' ,6);
INSERT INTO mystore.xyz_tablename VALUES('abc' ,7);
INSERT INTO mystore.xyz_tablename VALUES('abc' ,8);
select * from mystore.xyz_tablename;
mystore_owner=> select * from mystore.xyz_tablename;
x | y
-----+---
abc | 1
abc | 2
abc | 3
abc | 4
abc | 5
abc | 6
abc | 7
abc | 8
(8 rows)
INSERT INTO mystore.xyz_tablename(x,y)
SELECT a.*
FROM (SELECT * from mystore.xyz_tablename where y = 8 LIMIT 1) a
INNER JOIN (SELECT y FROM mystore.xyz_tablename LIMIT 5) b
ON (1=1)
;
OUTPUT
--------
5
(1 row)
mystore_owner=> select * from mystore.xyz_tablename;
x | y
-----+---
abc | 1
abc | 2
abc | 3
abc | 4
abc | 5
abc | 6
abc | 7
abc | 8
abc | 8
abc | 8
abc | 8
abc | 8
abc | 8
(13 rows)
Let us know if this works for your requirement .
The number of copies can be controlled via the limit clause which is now 5 , you can alter that to your wish . But you can select from other table also which has more rows . If the source table has < than clause then it will fail.