There are two concatenation operators available in Access: +
; and &
. They differ in how they deal with Null.
"foo" + Null
returns Null
"foo" & Null
returns "foo"
So if you want to update Null [My Column]
fields to contain "Prefix "
afterwards, use ...
SET [My Column] = "Prefix " & [My Column]
But if you prefer to leave it as Null, you could use the +
operator instead ...
SET [My Column] = "Prefix " + [My Column]
However, in the second case, you could revise the WHERE
clause to ignore rows where [My Column]
contains Null.
WHERE [Different Column]='someValue' AND [My Column] Is Not Null
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…