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deepaktibhe
Valued Contributor

difference

What is difference between peek(fieldname) and previous(fieldname).

Thanks

1 Solution

Accepted Solutions
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Not applicable

Re: difference

Hi Deepak,

Peek():

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.

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.

Previous():

previous(expression )

Returns the value of expression using data from the previous input record. 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 ...;

Source: Help from Qlikview.

Also refer to the blog post below:

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

Regards,

Pramod

View solution in original post

3 Replies
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Not applicable

Re: difference

Hi Deepak,

Peek():

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.

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.

Previous():

previous(expression )

Returns the value of expression using data from the previous input record. 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 ...;

Source: Help from Qlikview.

Also refer to the blog post below:

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

Regards,

Pramod

View solution in original post

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Re: difference

Hi,

Have a look at below post.

http://community.qlik.com/docs/DOC-4073

Regards

ASHFAQ

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MVP
MVP

Re: difference

Go thorugh the links suggested above. In brief, what I usually like to highlight is :

Peek() - Works on output

Previous() - Works on input