Basic SQL Statement Definitions

Question 1

What does SQL stand for?

Answer 1

Structured Query Language

Question 2

SELECT

Answer 2

The SELECT statement is used to select data from a database.

Question 3

SELECT DISTINCT

Answer 3

The SELECT DISTINCT statement is used to return only distinct (different) values.

Question 4

WHERE

Answer 4

The WHERE clause is used to filter records. It is used to extract only those records that fulfill a specified condition.

Question 5

AND

Answer 5

The AND operator displays a record if all the conditions separated by AND are TRUE.

Question 6

OR

Answer 6

The OR operator displays a record if any of the conditions separated by OR is TRUE.

Question 7

NOT

Answer 7

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

Question 8

ORDER BY

Answer 8

The ORDER BY keyword is used to sort the result-set in ascending or descending order. The ORDER BY keyword sorts the records in ascending order by default.

Question 9

DESC

Answer 9

Used with the ORDER BY keyword to sort the records in descending order.

Question 10

INSERT INTO

Answer 10

The INSERT INTO statement is used to insert new records in a table.

Question 11

NULL

Answer 11

A field with a NULL value is a field with no value.

Question 12

UPDATE

Answer 12

The UPDATE statement is used to modify the existing records in a table.

Question 13

DELETE

Answer 13

The DELETE statement is used to delete existing records in a table.

Question 14

SELECT TOP

Answer 14

The SELECT TOP clause is used to specify the number of records to return.

Question 15

MAX()

Answer 15

The MAX() function returns the largest value of the selected column.

Question 16

MIN()

Answer 16

The MIN() function returns the smallest value of the selected column.

Question 17

COUNT()

Answer 17

The COUNT() function returns the number of rows that matches a specified criterion.

Question 18

AVG()

Answer 18

The AVG() function returns the average value of a numeric column.

Question 19

SUM()

Answer 19

The SUM() function returns the total sum of a numeric column.

Question 20

LIKE

Answer 20

The LIKE operator is used in a WHERE clause to search for a specified pattern in a column.

Question 21

What are 2 wildcards often used in conjunction with the LIKE operator?

Answer 21

The percent sign (%) represents zero, one, or multiple characters.

The underscore sign (_) represents one, single character.

Question 22

Wildcard: *

Answer 22

Represents zero or more characters.

Question 23

Wildcard: ?

Answer 23

Represents a single character.

Question 24

Wildcard: []

Answer 24

Represents any single character within the brackets. Used with brackets [].

Question 25

Wildcard: !

Answer 25

Represents any character not in the brackets. Used with brackets [].

Question 26

Wildcard: -

Answer 26

Represents any single character within the specified range. Used with brackets [].

Question 27

Wildcard: #

Answer 27

Represents any single numeric character.

Question 28

Wildcard: %

Answer 28

Represents zero or more characters.

Question 29

Wildcard: _

Answer 29

Represents a single character.

Question 30

Wildcard: ^

Answer 30

Represents any character not in the brackets.

Question 31

IN

Answer 31

The IN operator allows you to specify multiple values in a WHERE clause.

Question 32

BETWEEN

Answer 32

The BETWEEN operator selects values within a given range. The values can be numbers, text, or dates.

Question 33

AS

Answer 33

Stands for Aliases. Aliases are used to give a table, or a column in a table, a temporary name.

Question 34

JOINS

Answer 34

A JOIN clause is used to combine rows from two or more tables, based on a related column between them.

Question 35

INNER JOIN

Answer 35

The INNER JOIN keyword selects records that have matching values in both tables.

Question 36

LEFT JOIN

Answer 36

The LEFT JOIN keyword returns all records from the left table (table1), and the matching records from the right table (table2). The result is 0 records from the right side, if there is no match.

Question 37

RIGHT JOIN

Answer 37

The RIGHT JOIN keyword returns all records from the right table (table2), and the matching records from the left table (table1). The result is 0 records from the left side, if there is no match.

Question 38

FULL JOIN (FULL OUTER JOIN)

Answer 38

The FULL OUTER JOIN keyword returns all records when there is a match in left (table1) or right (table2) table records.

Question 39

SELF JOIN

Answer 39

A self join is a regular join, but the table is joined with itself.

Question 40

UNION

Answer 40

The UNION operator is used to combine the result-set of two or more SELECT statements.

Question 41

GROUP BY

Answer 41

The GROUP BY statement groups rows that have the same values into summary rows, like “find the number of customers in each country”.

Question 42

HAVING

Answer 42

The HAVING clause was added to SQL because the WHERE keyword cannot be used with aggregate functions.

Question 43

EXISTS

Answer 43

The EXISTS operator is used to test for the existence of any record in a subquery.

Question 44

ANY

Answer 44

Allow you to perform a comparison between a single column value and a range of other values.

ANY means that the condition will be true if the operation is true for any of the values in the range.

Question 45

ALL

Answer 45

Allow you to perform a comparison between a single column value and a range of other values.

ALL means that the condition will be true only if the operation is true for all values in the range.

Question 46

SELECT INTO

Answer 46

The SELECT INTO statement copies data from one table into a new table.

Question 47

INSERT INTO SELECT

Answer 47

The INSERT INTO SELECT statement copies data from one table and inserts it into another table.

Question 48

CASE

Answer 48

The CASE expression goes through conditions and returns a value when the first condition is met (like an if-then-else statement). So, once a condition is true, it will stop reading and return the result. If no conditions are true, it returns the value in the ELSE clause.

If there is no ELSE part and no conditions are true, it returns NULL.

Question 49

ISNULL()

Answer 49

The SQL Server ISNULL() function lets you return an alternative value when an expression is NULL.

Question 50

Stored Procedure

Answer 50

A stored procedure is a prepared SQL code that you can save, so the code can be reused over and over again.

So if you have an SQL query that you write over and over again, save it as a stored procedure, and then just call it to execute it.

You can also pass parameters to a stored procedure, so that the stored procedure can act based on the parameter value(s) that is passed.