I'm a DB newbie, and am struggling with this. I have an existing table with the followi开发者_StackOverflow社区ng columns:
Showroom, Salesperson, Time1, Time2, Time3, Dte
I'm trying to delete all rows within the table that have either null or zero values in all 3 time columns. I tried the following:
DELETE FROM myTable
WHERE EXISTS(
SELECT *
FROM myTable
WHERE (Time1 IS NULL OR Time1 = 0)
AND (Time2 IS NULL OR Time2 = 0)
AND (Time3 IS NULL OR Time3 = 0)
)
Thankfully I'm working on a test version of the database, as I wiped out all of the data. Any help would truly be appreciated.
The query should be formatted like this:
DELETE
FROM myTable
WHERE (Time1 IS NULL OR Time1 = 0)
AND (Time2 IS NULL OR Time2 = 0)
AND (Time3 IS NULL OR Time3 = 0)
When doing DELETE
statements I think it is always best to first create your SELECT
statement, and then change it.
SELECT * --If this returns the correct records, simply change to DELETE
FROM myTable
WHERE (Time1 IS NULL OR Time1 = 0)
AND (Time2 IS NULL OR Time2 = 0)
AND (Time3 IS NULL OR Time3 = 0)
What you want is just;
DELETE myTable
WHERE
(Time1 IS NULL OR Time1 = 0)
AND (Time2 IS NULL OR Time2 = 0)
AND (Time3 IS NULL OR Time3 = 0)
The EXISTS
is superfluous (as is the FROM
- it isn't needed for DELETE
s):
DELETE myTable
WHERE ((Time1 IS NULL OR Time1 = 0)
AND (Time2 IS NULL OR Time2 = 0)
AND (Time3 IS NULL OR Time3 = 0))
Try this instead:
DELETE
FROM myTable
WHERE
(Time1 IS NULL OR Time1 = 0) AND
(Time2 IS NULL OR Time2 = 0) AND
(Time3 IS NULL OR Time3 = 0)
The reason all of your records are being deleted is because the EXISTS result is true as long as there exists a single record that has NULL or 0 for all three columns. Since your WHERE clause of the delete statement doesn't identify which records to delete, it is essentially the same as DELETE FROM myTable WHERE 1=1
DELETE myTable WHERE
(ISNULL(Time1,0) = 0) AND (ISNULL(Time2,0) = 0) AND (ISNULL(Time3,0) = 0)
Here is the query to delete blank rows as well as NULL
DELETE FROM table_name WHERE COL_NAME='' OR COL_NAME IS NULL;
What you can do is to create a select query in MS automatically, then find and replace symbols [
with (ISNULL([
, ]
with ],0) = 0)
.
and to get AND
condition for all numeric fields (ISNULL(Time1,0) = 0) AND
.
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