Difference between revisions of "SELECT names"
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Revision as of 18:37, 30 April 2015
name | continent |
---|---|
Afghanistan | Asia |
Albania | Europe |
Algeria | Africa |
Andorra | Europe |
Angola | Africa |
.... |
Pattern Matching Strings
This tutorial uses the LIKE operator to check names. We will be using the SELECT command on the table world:
You can use WHERE name LIKE 'B%'
to find the countries that start with "B".
- The % is a wild-card it can match any characters
Find the country that start with Y
SELECT name FROM world
WHERE name LIKE 'F%'
SELECT name FROM world
WHERE name LIKE 'Y%'
Find the countries that end with y
SELECT name FROM world
WHERE name LIKE 'T%'
SELECT name FROM world
WHERE name LIKE '%y'
Luxembourg has an x - so does one other country. List them both.
Find the countries that contain the letter x
SELECT name FROM world
WHERE name LIKE 'T%'
SELECT name FROM world
WHERE name LIKE '%x%'
Iceland, Switzerland end with land - but are there others?
Find the countries that end with land
SELECT name FROM world
WHERE name LIKE 'T%'
SELECT name FROM world
WHERE name LIKE '%land'
Columbia starts with a C and ends with ia - there are two more like this.
Find the countries that start with C and end with ia
SELECT name FROM world
WHERE name LIKE 'T%'
SELECT name FROM world
WHERE name LIKE 'C%ia'
Greece has a double e - who has a double o?
Find the country that has oo in the name
SELECT name FROM world
WHERE name LIKE '%ee%'
SELECT name FROM world
WHERE name LIKE '%oo%'
Bahamas has three a - who else?
Find the countries that have three or more a in the name
SELECT name FROM world
WHERE name LIKE 'T%'
SELECT name FROM world
WHERE name LIKE '%a%a%a%'
India and Angola have an n as the second character. You can use the underscore as a single character wildcard.
SELECT name FROM world
WHERE name LIKE '_n%'
ORDER BY name
Find the countries that have "t" as the second character.
SELECT name FROM world
WHERE name LIKE '_n%'
ORDER BY name
SELECT name FROM world
WHERE name LIKE '_t%'
ORDER BY name
Lesotho and Moldova both have two o characters separated by two other characters.
Find the countries that have two "o" characters separated by two others.
SELECT name FROM world
WHERE name LIKE '_n%'
SELECT name FROM world
WHERE name LIKE '%o__o%'
Cuba and Togo have four characters names.
Find the countries that have exactly four characters.
SELECT name FROM world
WHERE name LIKE 'Cu%'
SELECT name FROM world
WHERE name LIKE '____'
Harder Questions
Well done for getting this far.
The next questions are optional and only for students who are finding the basic questions too easy.
The capital of Luxembourg is Luxembourg. Show all the countries where the capital is the same as the name of the country
Find the country where the name is the capital city.
SELECT name, capital, continent
FROM world
WHERE name LIKE '%x%'
SELECT name FROM world
WHERE name = capital
The capital of Mexico is Mexico City. Show all the countries where the capital has the country together with the word "City".
Find the country where the capital is the country plus "City".
The function concat is short for concatenate - you can use it to combine two or more strings.
SELECT name, concat(name, 'town')
FROM world
WHERE name LIKE '%ina%'
SELECT name FROM world
WHERE capital = concat(name, ' City')
Find the capital and the name where the capital includes the name of the country.
SELECT name, capital FROM world
WHERE capital LIKE concat('%', name, '%')