Beginning SQL

Finally, if you want to use an alias that contains spaces or any other characters normally not permitted for
column names or aliases, then you must enclose the alias name inside square brackets, as shown below:
SELECT LastName AS Surname, FirstName AS [Christian Name]
FROM MemberDetails;
Using this SQL, the alias Christian Name has a space, so it’s enclosed inside the square brackets.
Square brackets allow you to use names for columns or aliases that contain characters not normally considered
legal. For example, you would receive an error if you tried to use the alias One***Two, as shown
in the following statement:
SELECT DateOfBirth AS One***Two FROM MemberDetails;
But if you put square brackets around the alias, the database system is happy:
SELECT DateOfBirth AS [One***Two] FROM MemberDetails;
Both Oracle and DB2 support a second way of concatenating: the CONCAT() function. You pass the two
things you want to join, either columns or literal strings, as arguments to the function, and the function
returns them joined. For example, to join FirstName and LastName columns, you would write the following
query:
SELECT CONCAT(FirstName, LastName) FROM MemberDetails;
Executing this query produces the following results:
KatieSmith
SusieSimons
JohnJackson
SteveGee
JohnJones
JennyJones
JackJohnson
SeymourBotts
JamieHills
StuartDales
WilliamDoors
DorisNight
Although CONCAT() does the same thing in Oracle and DB2, there are plenty of subtle differences. One
difference is that Oracle does its best to convert values into text. Although the following statement works
on Oracle, it produces an error in DB2:
SELECT CONCAT(DateOfBirth, LastName) FROM MemberDetails;
Extracting Information
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