Select Chapter ❯
MySQL Tutorial
MySQL Clauses
MySQL have different types of clauses which are used in querying a database like WHERE, ORDER BY, GROUP BY, LIMIT, HAVING etc.
WHERE Clause
WHERE clause is used to retrieve particular rows from the database.
$sql = "SELECT * from student_info where student_name = 'Rohit' ";
It retrieve all the rows where student_name is equal to Rohit
ORDER BY Clause
ORDER BY clause is used to specify the sort order for the rows in a result set.
Syntax
ORDER BY columnName ASC/DESC
/*It retrieve and sort all the rows in ascending order*/ $sql = "SELECT * from student_info where ORDER BY student_name "; or /*It retrieve and sort all the rows in descending order*/ $sql = "SELECT * from student_info where ORDER BY student_name DESC ";
GROUP BY Clause
GROUP BY clause is used to eliminate duplicate rows and returns only unique rows.
Syntax
GROUP BY columnName
$sql = "SELECT * from student_info where GROUP BY student_name ";
It returns only unique rows
LIMIT Clause
LIMIT clause is used to specify the maximum number of rows that are returned in the result set.
Syntax
LIMIT [offset], NumberOfRows
/*It returns first five rows from student_info table*/ $sql = "SELECT * from student_info LIMIT 5"; or /*It returns five rows starting from 3rd row */ $sql = "SELECT * from student_info LIMIT 2,5";
HAVING Clause
HAVING clause is used to determine which goups are included in the final results.
$sql = "SELECT * from student_info where GROUP BY student_name HAVING course='BCA' ";