Beginning SQL

Chapter 3
Even though DateOfBirth is a date column and not a character data type, if you try to execute the
same query in DB2, you get an error. For most of this book, you’ll find it easier to use the double vertical
pipe (||) to concatenate data.
That covers concatenation in Oracle and DB2. Now it’s time to look at MySQL’s way of concatenating.
MySQL
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MySQL concatenates using one of two functions. The first is the CONCAT() function, which works in a
way similar to CONCAT() used with Oracle and DB2. However, unlike under those database systems, it
can take two or more arguments. So, if you want to join three columns, you would write a query similar
to the following:
SELECT CONCAT(MemberId,FirstName,LastName) FROM MemberDetails;
Executing the query gives these results:
1KatieSmith
4SteveGee
5JohnJones
6JennyJones
7JohnJackson
8JackJohnson
9SeymourBotts
10SusieSimons
11JamieHills
12StuartDales
13WilliamDoors
14DorisNight
Notice that a numeric data type column is concatenated. MySQL’s CONCAT() function will, if possible,
convert numeric data types to string values before concatenating.
As well as columns, CONCAT() can also join string literals. Consider the following code:
SELECT CONCAT(‘The member is called ‘,FirstName,’ ‘,LastName) AS ‘Member Name’ FROM
MemberDetails;
Executing the preceding query creates the following results: