Look at the following table:
Orders Table
OrderId | ProductName | OrderDate |
---|---|---|
1 | Geitost | 2008-11-11 |
2 | Camembert Pierrot | 2008-11-09 |
3 | Mozzarella di Giovanni | 2008-11-11 |
4 | Mascarpone Fabioli | 2008-10-29 |
Now we want to select the records with an OrderDate of "2008-11-11" from the table above.
We use the following SELECT
statement:
The result-set will look like this:
OrderId | ProductName | OrderDate |
---|---|---|
1 | Geitost | 2008-11-11 |
3 | Mozzarella di Giovanni | 2008-11-11 |
Note: Two dates can easily be compared if there is no time component involved!
Now, assume that the "Orders" table looks like this (notice the added time-component in the "OrderDate" column):
OrderId | ProductName | OrderDate |
---|---|---|
1 | Geitost | 2008-11-11 13:23:44 |
2 | Camembert Pierrot | 2008-11-09 15:45:21 |
3 | Mozzarella di Giovanni | 2008-11-11 11:12:01 |
4 | Mascarpone Fabioli | 2008-10-29 14:56:59 |
If we use the same SELECT
statement as above:
we will get no result! This is because the query is looking only for dates with no time portion.
Tip: To keep your queries simple and easy to maintain, do not use time-components in your dates, unless you have to!
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