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CSS
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JQuery
What is jQuery? Benefits of using jQuery Include jQuery Selectors. Methods. The $ symbol and shorthand. Selecting elements Getting and setting content Adding and removing elements Modifying CSS and classes Binding and Unbinding events Common events: click, hover, focus, blur, etc Event delegation Using .on() for dynamic content Showing and hiding elements Fading elements in and out Sliding elements up and down .animate() Understanding AJAX .ajax() .load(), .get(), .post() Handling responses and errors. Parent Chlid Siblings Filtering Elements Using find Selecting form elements Getting form values Setting form values Form validation Handling form submissions jQuery plugins Sliders plugins $.each() $.trim() $.extend() Data attributes Debugging jQuery code
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Bootstrap 4
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PHP
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MY SQL
SQL Introduction Syntax Select statement Select Distinct WHERE Clause Order By SQL AND Operator SQL OR Operator SQL NOT Operator SQL LIKE SQL IN SQL BETWEEN SQL INSERT INTO SQL NULL Values SQL UPDATE SQL DELETE SQL TOP, LIMIT, FETCH FIRST or ROWNUM Clause SQL MIN() and MAX() Functions SQL COUNT() Function SQL SUM() SQL AVG() SQL Aliases SQL JOIN SQL INNER JOIN SQL LEFT JOIN SQL RIGHT JOIN SQL FULL OUTER JOIN SQL Self Join SQL UNION SQL GROUP BY SQL HAVING SQL EXISTS SQL ANY and ALL SQL SELECT INTO SQL INSERT INTO SELECT SQL CASE SQL NULL Functions SQL Stored Procedures SQL Comments SQL Operators SQL CREATE DATABASE SQL DROP DATABASE SQL BACKUP DATABASE SQL CREATE TABLE SQL DROP TABLE SQL ALTER TABLE SQL Constraints SQL NOT NULL SQL UNIQUE Constraint SQL PRIMARY KEY SQL FOREIGN KEY SQL CHECK Constraint SQL CREATE INDEX SQL AUTO INCREMENT SQL Dates SQL Views SQL Injection SQL Hosting SQL Data Types
SQL Dates
SQL provides several functions and types to work with dates and times. Here's an overview along with examples and their outputs.
Date and Time Data Types
DATE
: Stores date values (year, month, day).TIME
: Stores time values (hour, minute, second).DATETIME
: Stores date and time values.TIMESTAMP
: Stores a timestamp value that includes date and time.YEAR
: Stores a year value.
Getting the Current Date and Time
CURDATE()
: Returns the current date.CURTIME()
: Returns the current time.NOW()
: Returns the current date and time.CURRENT_TIMESTAMP()
: Synonym forNOW()
.
Example
SELECT CURDATE(); -- Output: '2024-07-25'
SELECT CURTIME(); -- Output: '14:35:06'
SELECT NOW(); -- Output: '2024-07-25 14:35:06'
Date and Time Functions
DATE()
: Extracts the date part of a datetime expression.TIME()
: Extracts the time part of a datetime expression.YEAR()
,MONTH()
,DAY()
: Extracts the year, month, and day parts respectively.
Example
SELECT DATE('2024-07-25 14:35:06'); -- Output: '2024-07-25'
SELECT TIME('2024-07-25 14:35:06'); -- Output: '14:35:06'
SELECT YEAR('2024-07-25'); -- Output: 2024
SELECT MONTH('2024-07-25'); -- Output: 7
SELECT DAY('2024-07-25'); -- Output: 25
Date Arithmetic
DATE_ADD()
,DATE_SUB()
: Adds or subtracts a date or time interval.DATEDIFF()
: Returns the number of days between two dates.
Example
SELECT DATE_ADD('2024-07-25', INTERVAL 10 DAY); -- Output: '2024-08-04'
SELECT DATE_SUB('2024-07-25', INTERVAL 10 DAY); -- Output: '2024-07-15'
SELECT DATEDIFF('2024-08-04', '2024-07-25'); -- Output: 10
Date Formatting
DATE_FORMAT()
: Formats a date according to a specified format.
Example
SELECT DATE_FORMAT('2024-07-25', '%W, %M %d, %Y'); -- Output: 'Thursday, July 25, 2024'
Practical Use Case
Suppose we have a table called orders
with a column order_date
of type DATETIME
. We want to get all orders from the last 30 days.
Example Query
SELECT * FROM orders
WHERE order_date >= DATE_SUB(NOW(), INTERVAL 30 DAY);
Combining Date and Time Functions
You can combine multiple functions to achieve complex queries. For example, finding the difference in hours between two DATETIME
values.
Example
SELECT TIMESTAMPDIFF(HOUR, '2024-07-25 10:00:00', '2024-07-25 14:00:00'); -- Output: 4
Summary
SQL provides robust support for date and time manipulation. Understanding these functions and types allows you to perform various operations, such as extracting parts of dates, formatting dates, adding/subtracting intervals, and more.
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