topic joins in QlikView

joins

manoj217 — Wed, 25 Nov 2020 16:16:04 GMT

i have two tables for each table have 10 fields but i want to join 1 field in both table and suggest which function takes less memory and with fast operation

Re: joins

sonkumamon — Mon, 24 Jul 2017 06:22:05 GMT

Hi manoj,

Just have the fields you want to join have the same name while all the rest of the fields in both tables should have unique names.

Uri

Re: joins

stevedark — Mon, 24 Jul 2017 06:44:37 GMT

If there are different numbers of rows in each table (i.e. it is not a perfect unique key on both sides) then your best bet is certainly just to load them both in and have them associate in the data model on the single field that joins. Just make sure the field is named exactly the same on both sides.

If there are identical numbers of rows and perfect keys in the tables then a JOIN would be a better approach (ideally in SQL, but in Qlik script is fine also).

If there are only two or three columns in one of the tables then ApplyMap would be best.

These are not totally hard and fast rules - but certainly a good start point.

Steve

Re: joins

arvind_patil — Mon, 24 Jul 2017 07:00:17 GMT

Hi Manoj,

I Agree with Steve .

Thanks,

Arvind Patil

Re: joins

neha_shirsath — Mon, 24 Jul 2017 11:31:58 GMT

Hi Manoj,

There is no such rule for when to use join/concatenate or any other concept, it will change project to project according to requirement and data model.

You just have to be make sure about your data model/qvd's need to be optimized which will increase data model performance .

thanks,

Neha

Re: joins

Nagaraju_KCS — Mon, 24 Jul 2017 12:25:57 GMT

HI Manoj,

There is no such type of concepts, according to your requirement we have to follow Join/Concatenate/Keep

Join can be used to tackle the same kind of situation, but there is a difference which should be understood.

Join will combine the rows where the key values matches.

Concatenate append the rows of one table to another table. Conacetnate never merges any rows in it.

Keep two tables are not joined and will be stored in 2 separately named tables.

The keep keyword must always be preceded by one of the prefixes Inner, Left or Right