Retrieving Data

Question 1

SQL Statement and Case

Answer 1

– SQL statements are not case-sensitive.

Question 2

Use of White Space

Answer 2

– All extra white space within a SQL statement is ignored when that statement is processed.

Question 3

How Retrieve Top 5 rows in different DBMS (MS SQL Server, DB2, Oracle, MySQL, MariaDB, PostgreSQL, SQLite)

Answer 3

• MS SQL Server – SELECT TOP 5 prod_name FROM Products;
• DB2 – SELECT prod_name FROM Products FETCH FIRST 5 ROWS ONLY;
• ORACLE – SELECT prod_name FROM Products WHERE ROWNUM ≤5;
• MySQL, MariaDB, PostgreSQL, SQLite - SELECT prod_name FROM Products LIMIT 5; - to get 5 next rows - SELECT prod_name FROM Products LIMIT 5 OFFSET 5;
  LIMIT 4 OFFSET 3 = LIMIT3,4 → Yes, they are reversed, so be careful

Question 4

Entire Line Comment

Answer 4

#

Question 5

Multiline Comment

Answer 5

/* smth */

Question 6

SELECT уник

Answer 6

SELECT DISTINCT