Problem with left join

[#1]

Hi,

I have one load and one left join. After that i do a concatenate and then a left join. Now the last left join doesn't have any effect. In this example, I expect George to have a place of 'par'. I have attached the script. Very easy to load and run at your end. Please help.

Thanks,

Ram

[#2 · Accepted solution]

Hi,

load * inline

[

name, age

ram,30

raj,40

ramji,50

];

left join

load * inline

[

name,place

ram,kmu

ramji,pap

];

gives

name	age	place
raj	40
ram	30	kmu
ramji	50	pap

concatenate

load * inline

[

name,age

george,25

Donald,28

];

gives

name	age	place
Donald	28
george	25
raj	40
ram	30	kmu
ramji	50	pap

now u do left join on the table above:

left join

load * inline

[

name, place

george,par

];

note that now the join takes place on the combination of two fields name+place as these are the two common fields in the two tables and not only on name.

So u dnt get what u need

To get the desired result, use:

tab1:

load * inline

[

name, age

ram,30

raj,40

ramji,50

];

left join

load * inline

[

name,place

ram,kmu

ramji,pap

];

tab2:

load * inline

[

name,age

george,25

Donald,28

];

left Join(tab2)

load * inline

[

name, place

george,par

];

Concatenate(tab2)

LOAD * Resident tab1;

DROP Table tab1;