Basic queries

Question 1

query data in columns c1 and c2 from table t

Answer 1

SELECT c1, c2 FROM t;

Question 2

Query all data from a table

Answer 2

SELECT * FROM t;

Question 3

query data and filter rows with a condition

Answer 3

SELECT c1, c2 FROM t

WHERE condition;

Question 4

Sort result set in ascending or descending order

Answer 4

SELECT c1, c2 FROM t

ORDER BY c1 ACS [DESC];

Question 5

query distinct rows from a tale

Answer 5

SELECT DISTINCT c1, c2 FROM t

Question 6

query how many rows are in a table

Answer 6

SELECT COUNT(*) FROM t

Question 7

find number of rows in a certain value of c1

Answer 7

SELECT c1, COUNT(*) FROM t

GROUP BY c1;

Question 8

find the total number of c1

Answer 8

SELECT SUM(c1) FROM t;

Question 9

find total number c2 of every c1 type of data

Answer 9

SELECT c1, SUM(c2) FROM t

GROUP BY c1;

Question 10

find the largest or smallest value in column c2

Answer 10

SELECT MAX(c2) [MIN(c2)] FROM t

Question 11

query the names of the most downloaded apps in each category

Answer 11

SELECT name, category, MAX(downloads)
FROM fake_apps
GROUP BY category;

Question 12

get the average value in column c1

Answer 12

SELECT AVG(c1) FROM t;