Databases
StackOverflow2013
Postsdbo
POUpdate with nested case for previous dates
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POUpdate with nested case for previous dates
    primarykey
    data
    text
    <p>I have a table with following columns:</p> <pre><code>Document_ID, Customer_ID, Date, LoanedMoney. </code></pre> <p>I've created a new <code>LoanedDate</code> column. I want to fill dates to <code>LoanedDate</code> in the following way: </p> <ol> <li>If the previous <code>Date</code> or previous date doesn't exists (it doesn't means always -1 day) with the same <code>Document_ID</code> and <code>Customer_ID</code> is null -> copy <code>LoanedMoney</code> value and update with that value; </li> <li>If the previous <code>Date</code> (it doesn't means always -1 day) with the same <code>Document_ID</code> and <code>Customer_ID</code> is not null -> copy it and update with that value; </li> <li>Else set <code>NULL</code> to <code>LoanedDate</code> </li> </ol> <p>My approximate logic to determine the previous Date (don't know how to put it in case statement):</p> <pre><code>SELECT TOP 1 Z1.Date FROM DBANME Z1 LEFT JOIN DBNAME Z2 ON Z1.Document_ID = Z2.Document_ID AND Z1.Customer_ID = Z2.Customer_ID AND CONVERT(CHAR(8), Z1.Date, 112) &lt; CONVERT(CHAR(8), Z2.Date, 112) ORDER BY Date DESC </code></pre> <p>I have done something like this:</p> <pre><code>DECLARE @Min datetime, @Prev datetime SELECT @Min = MIN(Date) FROM DBNAME UPDATE DBNAME SET LoanedDate CASE WHEN (LoanedMoney &gt; 0) -- SET @Prev = CASE WHEN @Prev IS NULL THEN Date ELSE @Prev ELSE NULL </code></pre> <p>What's the best way to implement it?</p> <p>What I have:</p> <pre><code>Document_ID, Customer_ID, Date, LoanedMoney, LoanedDate 1, 1, 2012-04-30, 30, NULL 1, 1, 2012-04-29, 50, NULL 1, 1, 2012-04-28, 50, NULL 1, 1, 2012-04-27, 0, NULL 1, 1, 2012-04-26, 20, NULL </code></pre> <p>What I expect:</p> <pre><code>Document_ID, Customer_ID, Date, LoanedMoney, LoanedDate 1, 1, 2012-04-30, 30, 2012-04-28 1, 1, 2012-04-29, 50, 2012-04-28 1, 1, 2012-04-28, 50, 2012-04-28 1, 1, 2012-04-27, 0, NULL -- Because LoanedMoney = 0 1, 1, 2012-04-26, 20, 2012-04-26 </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USuser1464922
    1. USuser1464922
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. COCan you add a few rows of sample data and expected results to your question?
      singulars
      1. POUpdate with nested case for previous dates
      1. USNenad Zivkovic
    2. COUpdate your question, please. Don't write additional data in comments, it's so unreadable this way.
      singulars
      1. POUpdate with nested case for previous dates
      1. USNenad Zivkovic
    3. COSorry, done. Please have a look above.
      singulars
      1. POUpdate with nested case for previous dates
      1. USuser1464922
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload