Web Programming - Week 7

Question 1

PHP connect to MySQL

Answer 1

$mysqli = new mysqli(“localhost”,”my_user”,”my_password”,”my_db”);

Question 2

How to check if PHP’s connection to MySQL has failed

Answer 2

if (!$conn) {
die(“Connection failed: “ . mysqli_connect_error());
}

Question 3

Create a select query

Answer 3

SELECT column_name(s) FROM table_name
OR
SELECT * FROM table_name

Question 4

How to execute a query

Answer 4

$result = mysql_query($conn, $sql);

Question 5

How to get data from a query

Answer 5

while ($row = mysqli_fetch_array($result)){

}

Question 6

Convert PHP to JSON

Answer 6

$alldata = array()
while ($row = mysqli_fetch_array($result, MYSQLI,ASSOC)){
$alldata[] =$row;
}

Question 7

How to close an opened database

Answer 7

mysqli_close($conn);

Question 8

Extract data from database

Answer 8

SELECT, FROM, WHERE

Question 9

What is WHERE used for

Answer 9

To filter records

Question 10

WHERE operators

Answer 10

AND/OR/NOT

Question 11

What is the LIKE operator used for

Answer 11

To search for a specified pattern in a where clause

Question 12

What is the COUNT function used for

Answer 12

To count the number of rows that matches a specific criterion

Question 13

Useful maths functions

Answer 13

AVG, Sum, MAX, MIN

Question 14

What is ORDER BY used for

Answer 14

To sort the result set in ascending or descending order

Question 15

What is JOIN used for

Answer 15

To combine rows from two or more tables

Question 16

What are the different types of JOIN

Answer 16

INNER, LEFT, RIGHT, FULL OUTER

Question 17

What is GROUP BY used for

Answer 17

Grouping rows that have the same values

Question 18

Convert MySQL date format YYYY-MM-DD to PHP d/m/Y

Answer 18

$mysql_date = "2021-03-15";
$convertedDate = date_format(date_create($mysql_date), "d/m/Y");

Question 19

Convert PHP date format d/m/Y to MySQL date format YYYY-MM-DD

Answer 19

$date = "15/03/2021";
$date1 = str_replace("/", "-", $date);
$convertedDate = date_format(date_create($date1), "Y-m-d";