Preceding Load is a very powerful functionality in QlikView in transforming the data.
What is Preceding load
It allows you to define multiple transformations and calculations within one load script which would otherwise will need to be created using separate load and resident load statements.
It takes input from the previous Select statement.
Preceding Load is invoked by checking the “preceding load ” while selecting the tables.
Another Advantage of Preceding Load is that it allows you to use QlikView functions in the Load script.
Let us see how your script will look when you don’t check the “preceding Load” while selecting the table.
Preceding Load not checked
Load Statement without Preceding Load
Loading table without preceding load will not allow you to use QlikView functions.
Now let us check “Preceding load” and see how the load script changes and what advantages it brings.
Load statement after checking “preceding load” check box
In this script you can see that preceding load takes the input from the previous Select Statement. You can select all the columns in the Select statement but in Load statement you can select the ones you need. Also observe Year and Month Calculations. Preceding Load allows you to use QlikView functions like Year,Month,ApplyMap etc.
There can be multiple preceding loads stacked one on the top of other.
Preceding load can be a useful tool to simplify your data transformations.
:
excellent and it is very clear explation inever saw in any another blogs
No words
Venkat:
Hope this topic was useful for you.
Though i was unable to understand your comment. Are you expecting something or am i missing something.
i am try to try multi load statement just above the SQL statement.
and it fails while reloading
—my script contains
load year(UPDATED_DATE) AS YEAR1;
LOAD MONTH(CREATED_DATE) AS DATEE;
SQL SELECT
“PRIMARY_KEY”,
“CREATED_DATE”,
“UPDATED_DATE”,
YEAR,
MONTH,
“AIRCRAFT_TYPE_ID”,
“DEPARTURES_SCHEDULED”,
“DEPARTURES_PERFORMED”,
“AVAILABLE_SEATS”,
“TRANSPORTED_PASSENGERS”,
“TRANSPORTED_FREIGHT”
FROM SCOTT.”FLIGHT_DATA_1″;
—- below is error after reload
Field not found –
SQL SELECT
“PRIMARY_KEY”,
“CREATED_DATE”,
“UPDATED_DATE”,
YEAR,
MONTH,
“AIRCRAFT_TYPE_ID”,
“DEPARTURES_SCHEDULED”,
“DEPARTURES_PERFORMED”,
“AVAILABLE_SEATS”,
“TRANSPORTED_PASSENGERS”,
“TRANSPORTED_FREIGHT”
FROM SCOTT.”FLIGHT_DATA_1″
but it was not giving any error if i have only one load statement.
Gurjeet:
Preceding load takes the input from the previous load statements and transform it.
Your correct statement should be LOAD *, MONTH(CREATED_DATE) AS DATEE;
This will include not only CREATED_DATE but also all other columns from the previous load statement.
Now you should not get any error as UPDATED_DATE will be present.
Also modify your load year(UPDATED_DATE) AS YEAR1; because this will load just the UPDATED_DATE
It should be load *, year(UPDATED_DATE) AS YEAR1;
because you want to include other columns also in the table but just want to transform UPDATED_DATE
Hi,
Good explanation for preceding load but I have a doubt here.
Just wanted know the necessity of using preceding LOAD statement, when we can do all the transformations with SQL.
Thanks
Srikanth