topic Re: Peek & Previous in QlikView

Peek & Previous

NavinReddy — Fri, 02 Aug 2013 06:59:43 GMT

Hi All

Give me some examples

peek and previous with inline load simple under standing

Thank in advance

rohith

Re: Peek & Previous

tresB — Fri, 02 Aug 2013 07:06:55 GMT

Have a look here

Basically, Peek() works on OUTPUT of load and the Previous() works on INPUT of load. The difference can be seen if you load a table with and without some WHERE condition for filtereing data.

Re: Peek & Previous

Fri, 02 Aug 2013 07:15:58 GMT

previous(expression )

Returns the value of expression using data from the previous input record that was not discarded due to a where clause. In the first record of an internal table the function will return NULL. The previous function may be nested in order to access records further back. Data are fetched directly from the input source, making it possible to refer also to fields which have not been loaded into QlikView, i.e. even if they have not been stored in its associative database.

Examples:

Load *, Sales / previous(Sales) as Increase from ...;

Load A, previous(previous( A )) as B from ...;

peek(fieldname [ , row [ , tablename ] ] )

Returns the contents of the fieldname in the record specified by row in the internal table tablename. Data are fetched from the associative QlikView database.

Fieldname must be given as a string (e.g. a quoted literal).

Row must be an integer. 0 denotes the first record, 1 the second and so on. Negative numbers indicate order from the end of the table. -1 denotes the last record read.

If no row is stated, -1 is assumed.

Tablename is a table label, see Table Labels, without the ending colon. If no tablename is stated, the current table is assumed. If used outside the load statement or referring to another table, the tablename must be included.

Examples:

peek( 'Sales' )
returns the value of Sales in the previous record read ( equivalent to previous(Sales) ).

peek( 'Sales', 2 )
returns the value of Sales from the third record read from the current internal table.

peek( 'Sales', -2 )
returns the value of Sales from the second last record read into the current internal table.

peek( 'Sales', 0, 'Tab1' )
returns the value of Sales from the first record read into the input table labeled Tab1.

Load A, B, numsum( B, peek( 'Bsum' ) ) as Bsum...;
creates an accumulation of B in Bsum.

Re: Peek & Previous

er_mohit — Fri, 02 Aug 2013 07:17:26 GMT

Go to this link

http://community.qlik.com/blogs/qlikviewdesignblog/2013/04/08/peek-vs-previous-when-to-use-each

http://qlikshare.com/172

The main difference is that Previous() fetches data from previous input record, whereas Peek() fetches data from previous output record. (Input to the Load statement and output of the Load statement.)

In addition, Peek() can be used to fetch data from other records than the previous and from other tables than the current, if the second and third parameters are used.

Re: Peek & Previous

Siva_Sankar — Fri, 02 Aug 2013 07:18:04 GMT

Check out this document. http://community.qlik.com/docs/DOC-4073 Regards. siva

Re: Peek & Previous

Fri, 02 Aug 2013 07:18:43 GMT

for more clear, see link

http://community.qlik.com/blogs/qlikviewdesignblog/2013/04/08/peek-vs-previous-when-to-use-each

http://community.qlik.com/thread/11135