SQL Sequence Subseq Function

The seq_subseq() function is used to extract a segment of the input sequence by specifying integer position arguments “from” and “to”.

The beginning position number ("from") can be greater than the ending position number ("to"). This allows iterating in reverse order. However, the input sequence should be fetched from the database directly, and the result should be used for fetching elements only in such case.

Following is an example script demonstrating the seq_subseq() function:

 
    SELECT symbol, seq_subseq(seq_search(day, 20130101, 20131231),1,4) as "2013_1-4"
    FROM Quote WHERE symbol='SYM0';
     
    symbol
    2013_1-4{}
    -------------------------------------------------
    SYM0
    {20130104, 20130106, 20130110, 20130123}
     

The example above returns the sequence containing elements 1 through 4 of the input sequence which contains the day values for year 2013.

Sample script

A sample script to demonstrate this select statement using xSQL can be run from the samples/xsql/scripts/financial directory with the following command:

     
    g 11