SQL Dates

SQL Dates

The most difficult part when working with dates in databases, is to be sure that the format of the date you are trying to insert/select, matches the format of the date column in the database.

SQL Date Data Types

Different SQL databases have various data types to store date and time values.

MySQL has the following date data types:

• DATE - format YYYY-MM-DD
• DATETIME - format: YYYY-MM-DD HH:MI:SS
• TIMESTAMP - format: YYYY-MM-DD HH:MI:SS
• TIME - format: HH:MI:SS
• YEAR - format YYYY or YY

SQL Server has the following date data types:

• DATE - format YYYY-MM-DD
• DATETIME - format: YYYY-MM-DD HH:MI:SS
• SMALLDATETIME - format: YYYY-MM-DD HH:MI:SS
• TIME - format: HH:MI:SS
• TIMESTAMP - format: a unique number

Note: The date data type are defined for a column upon creation of a new table in your database.

SQL Working with Dates

Look at the following table:

Orders Table

Now we want to select the records with an OrderDate of "2025-11-11" from the table above.

We use the following SELECT statement:

SELECT * FROM Orders WHERE OrderDate='2025-11-11'

The result-set will look like this:

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):

If we use the same SELECT statement as above:

SELECT * FROM Orders WHERE OrderDate='2025-11-11'

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!