What are some common clauses used with SELECT query in SQL?
Some common SQL clauses used in conjuction with a SELECT query are as follows:
WHERE clause in SQL is used to filter records that are necessary, based on specific conditions.
ORDER BY clause in SQL is used to sort the records based on some field(s) in ascending (ASC) or descending order (DESC).
SELECT *
FROM myDB.students
WHERE graduation_year = 2019
ORDER BY studentID DESC;
GROUP BY clause in SQL is used to group records with identical data and can be used in conjunction with some aggregation functions to produce summarized results from the database.
HAVING clause in SQL is used to filter records in combination with the GROUP BY clause. It is different from WHERE, since the WHERE clause cannot filter aggregated records.
SELECT COUNT(studentId), country
FROM myDB.students
WHERE country != "INDIA"
GROUP BY country
HAVING COUNT(studentID) > 5;
mysql> select * from books;
+------+--------+------+
| name | author | jb |
+------+--------+------+
| lkj | NULL | NULL |
| lkj | NULL | NULL |
| lkj | NULL | NULL |
+------+--------+------+
3 rows in set (0.00 sec)
mysql> select name ,author from books;
+------+--------+
| name | author |
+------+--------+
| lkj | NULL |
| lkj | NULL |
| lkj | NULL |
+------+--------+
3 rows in set (0.00 sec)
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