Copy data from one existing row to another existing row in SQL?

I have a table full of tracking data for as specific course, course number 6.

Now I have added new tracking data for course number 11.

Each row of data is for one user for one course, so for users assigned to both course 6 and course 11 there are two rows of data.

The client wants all users who have completed course number 6 any time after August 1st 2008 to also have completion marked for course 11. However I can't just convert the 6 to 11 because they want to preserve their old data for course 6.

So for every row that has a course number of 6, is marked as complete, and is greater than the date August 1st 2008, I want to write the completion data over the row that contains the tracking for course 11 for that specific user.

I would need to carry over the data from the course 6 row to the course 11 row so things like user score and date of posted completion is moved over.

Here is the structure of the table:

userID (int)
courseID (int)
course (bit)
bookmark (varchar(100))
course_date (datetime)
posttest (bit)
post_attempts (int)
post_score (float)
post_date (datetime)
complete (bit)
complete_date (datetime)
exempted (bit)
exempted_date (datetime)
exempted_reason (int)
emailSent (bit)

Some values will be NULL and userID/courseID obviously won't be carried over as that is already in the right place.

Solution 1:

Maybe I read the problem wrong, but I believe you already have inserted the course 11 records and simply need to update those that meet the criteria you listed with course 6's data.

If this is the case, you'll want to use an UPDATE...FROM statement:

UPDATE MyTable
SET
    complete = 1,
    complete_date = newdata.complete_date,
    post_score = newdata.post_score
FROM
    (
    SELECT
        userID,
        complete_date,
        post_score
    FROM MyTable
    WHERE
        courseID = 6
        AND complete = 1
        AND complete_date > '8/1/2008'
    ) newdata
WHERE
    CourseID = 11
    AND userID = newdata.userID

See this related SO question for more info

Solution 2:

UPDATE c11
SET
    c11.completed= c6.completed,
    c11.complete_date = c6.complete_date,
-- rest of columns to be copied
FROM courses c11 inner join courses c6 on
    c11.userID = c6.userID 
    and c11.courseID = 11 and c6.courseID = 6
     -- and any other checks

I have always viewed the From clause of an update, like one of a normal select. Actually if you want to check what will be updated before running the update, you can take replace the update parts with a select c11.*. See my comments on the lame duck's answer.

Solution 3:

Copy a value from one row to any other qualified rows within the same table (or different tables):

UPDATE `your_table` t1, `your_table` t2
SET t1.your_field = t2.your_field
WHERE t1.other_field = some_condition
AND t1.another_field = another_condition
AND t2.source_id = 'explicit_value'

Start off by aliasing the table into 2 unique references so the SQL server can tell them apart

Next, specify the field(s) to copy.

Last, specify the conditions governing the selection of the rows

Depending on the conditions you may copy from a single row to a series, or you may copy a series to a series. You may also specify different tables, and you can even use sub-selects or joins to allow using other tables to control the relationships.

Solution 4:

Use SELECT to Insert records

INSERT tracking (userID, courseID, course, bookmark, course_date, posttest, post_attempts, post_score, post_date, complete, complete_date, exempted, exempted_date, exempted_reason, emailSent) 
SELECT userID, 11, course, bookmark, course_date, posttest, post_attempts, post_score, post_date, complete, complete_date, exempted, exempted_date, exempted_reason, emailSent
FROM tracking WHERE courseID = 6 AND course_date > '08-01-2008'