topic Re: when to use Join and when to use Keep ? in QlikView

when to use Join and when to use Keep ?

nikhilgarg — Mon, 25 May 2015 08:58:55 GMT

Helo,

Can anyone tell me scenarios when to use Join and when to use Keep ?

tHanks

Re: when to use Join and when to use Keep ?

simospa — Mon, 25 May 2015 09:00:05 GMT

See Understanding Join, Keep and Concatenate

Re: when to use Join and when to use Keep ?

prma7799 — Mon, 25 May 2015 09:00:53 GMT

Hi Nikhil,

Please check below

Re: Understanding Join, Keep and Concatenate

Difference between keep and joins with example

Re: when to use Join and when to use Keep ?

nikhilgarg — Mon, 25 May 2015 09:02:18 GMT

Hey,

Thanks but i have already gone thru these links. But i need to know when to use Joins na dwhen to use Keep

Thanks

Re: when to use Join and when to use Keep ?

nikhilgarg — Mon, 25 May 2015 09:02:33 GMT

Hey,

Thanks but i have already gone thru these links. But i need to know when to use Joins na dwhen to use Keep

Thanks

Re: when to use Join and when to use Keep ?

prma7799 — Mon, 25 May 2015 09:06:40 GMT

Hi Nikhil,

When using Join after joins (Left, Right, Inner, Outer) you get single table but after Keep join Join is perform but you get second table also.

Thanks

Re: when to use Join and when to use Keep ?

prma7799 — Mon, 25 May 2015 09:07:31 GMT

See below more idea.

Understanding Join, Keep and Concatenate

Re: when to use Join and when to use Keep ?

buzzy996 — Mon, 25 May 2015 09:09:47 GMT

u can use joins, u want to put ur 2 tables INPUT data into ONE OUT PUT TABLE after joins used.

u can use keep, u want to put ur 2 tables INPUT data into TWO OUT PUT TABLES after joins(KEEP) used.

Re: when to use Join and when to use Keep ?

jagan — Mon, 25 May 2015 09:24:38 GMT

Hi Nikhil,

Generally Join is used to join two tables into a single table. But sometimes it is not possible to join tables with many to many mapping.

Lets take and example:

Table1:

ID, Status, Date

1, Invoice Raised, 1/1/2015

1, Invoice Approved, 1/2/2015

DetailTable:

ID, Amount

1, 100

1, 200

1, 300

2, 200

When you use join for the above tables it creates 6 records (2 * 3) because of many to many join. Also we need to exclude ID 2 from DetailTable. If we use Sum(Amount) you will get 1200, it is incorrect. So by using Left Keep we can fix this.

Hope this helps you.

Regards,

Jagan.

Re: when to use Join and when to use Keep ?

nikhilgarg — Mon, 25 May 2015 10:09:08 GMT

Hey thanks it helps but i didn't understand dat u said total 1200 is

incorrect but for id 1 total sld be 1200 as there are 2 different status to

id 1. Can u plz explain a bit more.

Re: when to use Join and when to use Keep ?

engishfaque — Mon, 25 May 2015 10:15:37 GMT

Dear Nikhil,

Keep and Join works the same way but there is littlebit difference.

Instead of joining the result in the same table, Keep statement keeps the original table and provide us result into another table.

Kind regards,

Ishfaque Ahmed

Re: when to use Join and when to use Keep ?

vardhancse — Mon, 25 May 2015 10:26:48 GMT

Hi,

Technically both join and keep are one and the same, the one only difference is the view of the table after join what we see in data model.

In join the tables will be merged into one single table based on the join the data will be present in one single table.

In keep based on the condition the tables will be merger but in data model view we can see separate tables.

Re: when to use Join and when to use Keep ?

Mon, 25 May 2015 10:28:41 GMT

Hi,

About Join & Keep are provide similar results, but system performance is better while using KEEP function on a huge data set compare to JOIN function. Number of records gets increased using JOIN as they merge into a single table but coming to KEEP the record count remains same for each table but provides the desired results and they are in denormalized format.

With less amount of data that doesn't varies the performance if we go with JOIN or KEEP.

I hope this might gives some more information.

Regards,

Satish.

Re: when to use Join and when to use Keep ?

jagan — Tue, 26 May 2015 04:21:17 GMT

Yes, but the actual salary is 600 as per the table, we should not duplicate this, it is wrong to display 1200 instead of 600. This is just an example to understand. If there is many to many mapping between tables then Keep will be very helpful.

Re: when to use Join and when to use Keep ?

Anonymous — Wed, 08 Feb 2017 10:17:23 GMT

Like other user said

- if you have one to many or many to many relationship we should use Keep. Because if we use join we are duplicating data.

A simple example of that would be:

TableA:

load * inline

[

Key,A

1,A1

2,A2

3,A3

];

TableC:

load * inline

[

Key,C

1,C1

1,C11

1,C111

2,C2

4,C4

];

that give use to tables .

When we use a inner joing we are having that:

where of course we are duplicating the A1 value for nothing.

If we use a Keep.

Hope it helps , Enrique