Doubt regarding Join

[markgraham123]

Hi all,

I'm a QLikView learner.

I was just eager to know whether

Table:

Table1

Load * from Table1;

Join

Load * from Table2;

Join

Load * from Table3;

is same as-----------------------------------------------

Table1:

Load * from Table1;

Table2:

Load * from Table2;

Table3:

Load * from Table3;

Table4:

Load* Resident Table1;

Join

Load* Resident Table2;

Join

Load* Resident Table3;

Drop Tables Table1, Tabl2, Table3;

[swuehl]

As long as Table1, Table2, Table3 don't have the same fields, so they would autoconcatenate in the second case...

And your resulting table is differently named in the two cases.

[markgraham123]

I do have a key with same name in 3 tables which joins 3 of the tables.

[swuehl]

No, I was talking about autoconcatenation, QV will automatically concatenate tables when they show the same number and names of fields. This will not happen if the tables only share a subset of fields (like a single key field).

[markgraham123]

Hi,

I'm not able to understand the response.

[swuehl]

Table1:

LOAD Field1,

          Field2

FROM Table1;

Table2:

LOAD Field1,

          Field2

FROM Table2;

After script execution, there will be only Table1 in your data model, because of auto-concatenating the two tables (same number of fields and fields have same name, all fields are keys).

If you want to prevent this, use NOCONCATENATE LOAD prefix:

Table1:

LOAD Field1,

          Field2

FROM Table1;

Table2:

NOCONCATENATE

LOAD Field1,

          Field2

FROM Table2;

But now the two tables are linked by two fields --> synthetic key is created.

[sunny_talwar]

So I think swuehl‌ means that if the name of the fields between the three tables are exactly the same, they will auto-concatenate. These two can be safely considered equivalent:

Table:

Table1

Load * from Table1;

Join

Load * from Table2;

Join

Load * from Table3;

is same as-----------------------------------------------

Table1:

Load * from Table1;

Table2:

NoConcatenate

Load * from Table2;

Table3:

NoConcatenate

Load * from Table3;

Table4:

Load* Resident Table1;

Join

Load* Resident Table2;

Join

Load* Resident Table3;

Drop Tables Table1, Tabl2, Table3;

HTH

Best,

Sunny

[markgraham123]

THanq swuehl‌

[markgraham123]

THanq Sunny.

[sunny_talwar]

No problem Mark

Glad we were able to help.

Best,

Sunny