Thursday, July 15, 2010

SQL Wildcards

SQL wildcards can be used when searching for data in a database.


SQL WILDCARDS

SQL wildcards can substitute for one or more characters when searching for data in a database.
SQL wildcards must be used with the SQL LIKE operator.
With SQL, the following wildcards can be used:
WildcardDescription
%A substitute for zero or more characters
_A substitute for exactly one character
[charlist]Any single character in charlist
[^charlist]
or
[!charlist]
Any single character not in charlist



SQL WILDCARD EXAMPLES

We have the following "Persons" table:
P_IdLastNameFirstNameAddressCity
1HansenOlaTimoteivn 10Sandnes
2SvendsonToveBorgvn 23Sandnes
3PettersenKariStorgt 20Stavanger



USING THE % WILDCARD

Now we want to select the persons living in a city that starts with "sa" from the "Persons" table.
We use the following SELECT statement:
SELECT * FROM Persons
WHERE City LIKE 'sa%'
The result-set will look like this:
P_IdLastNameFirstNameAddressCity
1HansenOlaTimoteivn 10Sandnes
2SvendsonToveBorgvn 23Sandnes
Next, we want to select the persons living in a city that contains the pattern "nes" from the "Persons" table.
We use the following SELECT statement:
SELECT * FROM Persons
WHERE City LIKE '%nes%'
The result-set will look like this:
P_IdLastNameFirstNameAddressCity
1HansenOlaTimoteivn 10Sandnes
2SvendsonToveBorgvn 23Sandnes



USING THE _ WILDCARD

Now we want to select the persons with a first name that starts with any character, followed by "la" from the "Persons" table.
We use the following SELECT statement:
SELECT * FROM Persons
WHERE FirstName LIKE '_la'
The result-set will look like this:
P_IdLastNameFirstNameAddressCity
1HansenOlaTimoteivn 10Sandnes
Next, we want to select the persons with a last name that starts with "S", followed by any character, followed by "end", followed by any character, followed by "on" from the "Persons" table.
We use the following SELECT statement:
SELECT * FROM Persons
WHERE LastName LIKE 'S_end_on'
The result-set will look like this:
P_IdLastNameFirstNameAddressCity
2SvendsonToveBorgvn 23Sandnes



USING THE [CHARLIST] WILDCARD

Now we want to select the persons with a last name that starts with "b" or "s" or "p" from the "Persons" table.
We use the following SELECT statement:
SELECT * FROM Persons
WHERE LastName LIKE '[bsp]%'
The result-set will look like this:
P_IdLastNameFirstNameAddressCity
2SvendsonToveBorgvn 23Sandnes
3PettersenKariStorgt 20Stavanger
Next, we want to select the persons with a last name that do not start with "b" or "s" or "p" from the "Persons" table.
We use the following SELECT statement:
SELECT * FROM Persons
WHERE LastName LIKE '[!bsp]%'
The result-set will look like this:
P_IdLastNameFirstNameAddressCity
1HansenOlaTimoteivn 10Sandnes

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