Record count using Read()

问题

I am trying to figure out how to get the max record count before i populate a listview grid. I'm using the Oracle 10g DB and I've tried:

SELECT COUNT(*) as countNum, status, date, theTitle, theMessage, date2 " & _
       "FROM blah blah...

messagebox.show(dr(0))

But that makes the SQL query crash. It doesnt seem as though i am about to put anything related to "count" in my query or it will crash so is there any other way i can see how many records it returns other than that?

Thanks! :o)

David

回答1:

Use analytical count like so: SELECT COUNT(*) over () as countNum, status, date, theTitle, theMessage, date2 " & _ "FROM blah blah

回答2:

When using an aggregate function such as count you need to use a group by clause for all those fields in your result set that are not the result of an aggregate function.

回答3:

I wrote your query once in a kind of dynamic view in the WITH clause
and combine a count and select over this query in one select.

WITH query AS (
 SELECT *
 FROM foobar
 WHERE foo = 1
)
SELECT
  ( SELECT COUNT(*) FROM query ) cnt,
  status,
  date,
  theTitle,
  theMessage
FROM query

回答4:

I would use THIS to retrieve a simple count of records. Not sure why you would want to pull any other fields in this operation. If there are selection criteria, apply a WHERE or HAVING clause (as appropriate):

SELECT COUNT(YourPrimaryKey) As RecordCount
FROM YourTable
GROUP BY YourPrimaryKey

THen in your code use cmd.ExecuteScalar to retrieve the result . . .

来源：https://stackoverflow.com/questions/4829329/record-count-using-read