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for it in the INSERT statement. For now, we’re just taking advantage of the fact that the Address column
is not a required column — that is, it accepts NULLs. Since we’re not providing a value for this column and
since it has no default (we’ll see more on defaults later on), this column will be set to NULL when we perform
our INSERT. Let’s verify that by rerunning our test SELECT statement with one slight modification:
SELECT *
FROM Stores
WHERE StoreCode = ‘TST2’;
Now we see something a little different:
StoreCode Name Address City State Zip
--------- ----------- --------------- ------- -------- ------
TST2 Test Store NULL Here NY 00319
(1 row(s) affected)
Notice that a NULL was inserted for the column that we skipped.
Note that the columns have to be nullable in order to do this. What does that mean? Pretty much what it
sounds like: It means that you are allowed to have NULL values for that column. Believe me, we will be
discussing the nullability of columns at great length in this book, but for now, just realize that some columns
allow NULLs and some don’t. We can always skip providing information for columns that allow NULLs.
If, however, the column is not nullable, then one of three conditions must exist, or we will receive an
error and the INSERT will be rejected:
❑ The column has been defined with a default value. A default is a constant value that is inserted if
no other value is provided. We will learn how to define defaults in Chapter 7.
❑ The column is defined to receive some form of system-generated value. The most common of
these is an IDENTITY value (covered more in the design chapter), where the system typically
starts counting first at one row, increments to two for the second, and so on. These aren’t really
row numbers, as rows may be deleted later on and numbers can, under some conditions, get
skipped, but they serve to make sure each row has its own identifier.
❑ We supply a value for the column.
Just for completeness, let’s perform one more INSERT statement. This time, we’ll insert a new sale into
the Sales table. To view the properties of the Sales table, we can either open its Properties dialog as we
did with the Stores table, or we can run a system-stored procedure called sp_help. sp_help will
report information about any database object, user-defined data type, or SQL Server data type. The syntax
for using sp_help is as follows:
EXEC sp_help
To view the properties of the Sales table, we just have to type the following into the Query window:
EXEC sp_help Sales;
Chapter 3: The Foundation Statements of T-SQL
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