- . , SELECT : " , ?".
, SELECT, Browse `cities`. SELECT:
SELECT * FROM `cities` LIMIT 0,30;
" ". FROM , . LIMIT 0,30 0 ( ), 30 .
. 4
Search SELECT. Search cities, , :
`population` :
.5
phpMyAdmin :
SELECT `city_name`, `population`
FROM `cities`
WHERE 1
ORDER BY `population` DESC LIMIT 0,30;
, , . WHERE 1, phpMyAdmin-, . , . , ORDER BY, , DESC ( ASC ).
SQL-
- SQL-query: Edit, , "Query". `country`:
SELECT `city_name`, `population`
FROM `cities`
WHERE country_code = 'zh'
ORDER BY `population` DESC;
, . . - :
100000:
WHERE population > 100000 AND country_code = 'ca';
, "A":
WHERE city_name like 'A%'
. :
SELECT country_code, AVG(population)
FROM cities
GROUP BY country_code
- MIN(), MAX(), SUM() COUNT(), , , , . , :
SELECT country_code, count(city_name) FROM cities
GROUP BY country_code;
|
|
, , . . , , ; , .
, FROM , . , ( , ).
SELECT cities.city_name, cities.population, countries.country_name
FROM cities, countries
WHERE cities.country_code = countries.country_code LIMIT 0,30
PHP