SQL

Question 1

select data from a database

Answer 1

SELECT

Question 2

return only distinct (different) values

Answer 2

SELECT DISTINCT column1, column2, …

FROM table_name;

Question 3

extract only those records that fulfill a specified condition

Answer 3

SELECT column1, column2, …
FROM table_name
WHERE condition;

Question 4

Text Fields vs. Numeric Fields

Answer 4

SQL requires single quotes around text values

Question 5

To specify multiple possible values for a column

Answer 5

IN
SELECT * FROM Customers
WHERE City IN (‘Paris’,’London’);

Question 6

Search for a pattern

Answer 6

LIKE
SELECT * FROM Customers
WHERE City LIKE ‘s%’;

Question 7

Between a certain range

Answer 7

BETWEEN
SELECT * FROM Products
WHERE Price BETWEEN 50 AND 60;

Question 8

Not equal

Answer 8

<> or some version !=

Question 9

operator displays a record if all the conditions separated

Answer 9

AND
SELECT column1, column2, …
FROM table_name
WHERE condition1 AND condition2 AND condition3 …;

Question 10

operator displays a record if any of the conditions separated

Answer 10

OR
SELECT column1, column2, …
FROM table_name
WHERE condition1 OR condition2 OR condition3 …;

Question 11

displays a record if the condition(s) is NOT TRUE

Answer 11

NOT
SELECT column1, column2, …
FROM table_name
WHERE NOT condition;

Question 12

sorts the records in ascending order

Answer 12

ORDER BY ASC
SELECT column1, column2, …
FROM table_name
ORDER BY column1, column2, … ASC

Question 13

sorts the records in descending order

Answer 13

ORDER BY DESC
SELECT column1, column2, …
FROM table_name
ORDER BY column1, column2, … DESC;

Question 14

insert new records in a table

Answer 14

INSERT INTO
INSERT INTO table_name (column1, column2, column3, …)
VALUES (value1, value2, value3, …);

Question 15

a field with no value

Answer 15

NULL

Question 16

Test for NULL Values

Answer 16

IS NULL Syntax
or IS NOT NULL
SELECT column_names
FROM table_name
WHERE column_name IS NULL;

Question 17

modify the existing records in a table

Answer 17

UPDATE
UPDATE table_name
SET column1 = value1, column2 = value2, …
WHERE condition;

Question 18

delete existing records in a table

Answer 18

DELETE

DELETE FROM table_name WHERE condition;

Question 19

used to specify the number of records to return.

Answer 19

SELECT column_name(s)
FROM table_name
WHERE condition
LIMIT number;