| Author: Ashutosh 31 Aug 2007 | Member Level: Gold | Rating:  Points: 2 |
Hi
COUNT(ColumnName)==> Returns the count of rows in a table by eliminating NULL values;
COUNT(*) ==>returns the cardinality (total number of rows) for an entire table.
The fact that COUNT(*) and COUNT(column) treat NULLs differently can be used to your advantage in many situations such as calculating the NULLRows
Hope this gives you differece.
- Regards
Ashutosh
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| Author: Bindu Rajkumar 31 Aug 2007 | Member Level: Bronze | Rating: Points: 2 |
Let b_table having one column name
the following is result of select * from b_table
name
----------
raja
bindu
Null
kumar
1.select count(*) from b_table
result is
4
2. select count(name) from b_table
result is
3
here the thing is in second query the null value is not taken. in the 1 query all rows will returns no matter which value it may contains whether null or any value
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| Author: sriram 10 Sep 2007 | Member Level: Silver | Rating: Points: 2 |
select count(*) from emp- it will count null values also
select count(empid) from emp it wont count null values
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