Beginning SQL

Chapter 5
184
SELECT FirstName,
LastName, City,
COALESCE(FirstName + ‘ ‘ + LastName + ‘ lives in ‘ + City,
‘We have no details for ‘ + FirstName + ‘ ‘ + LastName,
‘No data available’)
FROM MemberDetails;
For the other database systems — IBM DB2, MySQL, and Oracle — the query should read as follows:
SELECT FirstName, LastName, City,
COALESCE(
CONCAT( CONCAT(FirstName,’ ‘), CONCAT(CONCAT(LastName, ‘ lives in ‘), City)),
CONCAT(‘We have no details for ‘,CONCAT(CONCAT(FirstName,’ ‘),LastName)),
‘No data available’)
FROM MemberDetails;
Running either query gives the following results:
FirstName LastName City COALESCE(
CONCAT( CONCAT(FirstName,’ ‘),
CONCAT(CONCAT(LastName, ‘ lives in ‘), City)),
CONCAT(‘We have no details for
‘,CONCAT(CONCAT(FirstName,’ ‘),LastName)),
‘No data available’)
Katie Smith Townsville Katie Smith lives in Townsville
Steve Gee New Town Steve Gee lives in New Town
John Jones Orange Town John Jones lives in Orange Town
Jenny Jones Orange Town Jenny Jones lives in Orange Town
John Jackson Orange Town John Jackson lives in Orange Town
Jack Johnson Big City Jack Johnson lives in Big City
Seymour Botts Windy Village Seymour Botts lives in Windy Village
Susie Simons Townsville Susie Simons lives in Townsville
Jamie Hills Orange Town Jamie Hills lives in Orange Town
Stuart Dales Windy Village Stuart Dales lives in Windy Village
William Doors Big City William Doors lives in Big City
Doris Night Dover Doris Night lives in Dover
Catherine Hawthorn NULL We have no details for Catherine Hawthorn
To explain this relatively complex SQL, consider the three arguments passed to the COALESCE() function.
The first argument appears below:
CONCAT( CONCAT(FirstName,’ ‘), CONCAT(CONCAT(LastName, ‘ lives in ‘), City)),