Databases
StackOverflow2013
Postsdbo
POSQL Server IF NOT EXISTS Usage?
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POSQL Server IF NOT EXISTS Usage?
    primarykey
    data
    text
    <p>Ok, so my schema is this:</p> <p>Table: Timesheet_Hours</p> <p>Columns:</p> <ul> <li>Timesheet_Id (PK, int)</li> <li>Staff_Id (int)</li> <li>BookedHours (int)</li> <li>Posted_Flag (boolean)</li> </ul> <p>This is an extremely simplified version of the table, but it will serve for the purposes of this explaination. Assume that a person can only ever have one timesheet record.</p> <p>What I'm trying to do is add records to another table, called WorkLog. Each record here has a time associated with it. When that table is updated, I want to update Timesheet_Hours as well.</p> <p>Before I update Timesheet_Hours, I want to check first that the relevant Timesheets haven't already been posted, and then I want to check if there is in fact a record to update in the first place.</p> <p>The first part of the if statement, which checks to see that the timesheets haven't already been posted, works fine. The problem is the second part. It is checkint to see that the record it is going to update already exists. The issue is that it always raises an error.</p> <p>NB: The code below is extracted from a stored procedure run by the update, insert and delete triggers on the WorkLog table. @PersonID is one of the parameters to that table. The stored procedure works fine if I comment out the second part of this statement.</p> <pre><code>IF EXISTS ( SELECT 1 FROM Timesheet_Hours WHERE Posted_Flag = 1 AND Staff_Id = @PersonID ) BEGIN RAISERROR('Timesheets have already been posted!', 16, 1) ROLLBACK TRAN END ELSE IF NOT EXISTS ( SELECT 1 FROM Timesheet_Hours WHERE Staff_Id = @PersonID ) BEGIN RAISERROR('Default list has not been loaded!', 16, 1) ROLLBACK TRAN END </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USRyan Kirkman
    1. USRyan Kirkman
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POSQL Server IF NOT EXISTS Usage?
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POSQL Server IF NOT EXISTS Usage?
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POSQL Server IF NOT EXISTS Usage?
      1. This table or related slice is empty.
      1. VTUpMod
    1. COIs 1 a name of a column in your Timesheet_Hours table?
      singulars
      1. POSQL Server IF NOT EXISTS Usage?
      1. USSirDemon
    2. CONo, it is not. As I'm using EXISTS, I was just following what I thought was standard practice in sub-queries using EXISTS.
      singulars
      1. POSQL Server IF NOT EXISTS Usage?
      1. USRyan Kirkman
    3. CO1 in that case is just a constant. All he cares about is that a row is returned, not the value of any columns. Using a constant is usually faster than using * or a specific column list.
      singulars
      1. POSQL Server IF NOT EXISTS Usage?
      1. USRick
 

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