Inserting values based on another column SQL

Question

I've added the column DVDAtTime and I'm and trying to insert values using a subquery. Seems rather straight forward but I keep getting an error that I can't insert null into (I believe) an unrelated field in the table. Ultimately, DVDAtTime should be the number shown in MembershipType

My code is as follows:

Insert Into Membership(DVDAtTime)
Select LEFT(MembershipType,1)
FROM Membership

INSERT creates new rows. Because you specify only one column, those new rows have NULL for all the other columns. UPDATE, however, amends the contents of existing rows. — MatBailie
– MatBailie, Commented Jul 3, 2021 at 21:44

Gordon Linoff · Accepted Answer · 2021-07-03 21:42:07Z

2

I suspect you want to update each existing row, not insert new rows:

update membership
    set DVDAtTime = left(MembershipType, 1)

answered Jul 3, 2021 at 21:42

Gordon Linoff

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