Oracle-Sql-Basic_Queries

1.Get the first_day of the Month

SQL> SELECT TRUNC (SYSDATE, 'MONTH') "First day of current month"

  2      FROM DUAL;

First day

---------

01-AUG-14

2.Get the Last_day of  the Current Month

SELECT TRUNC (LAST_DAY (SYSDATE)) "Last day of current month"

    FROM DUAL;

3.Write a query that check if a table exists in the current database schema.

 SELECT table_name

   FROM user_tables

  WHERE table_name = 'EMPLOYEES'

4. Write a query that shows a Table structure.

Desc Employees;

5.Write a query to display Current User.

Show User;

6.Write a query to find last_record from a table.

 SELECT employee_id,last_name,job_id

   FROM employees

  WHERE ROWID IN (SELECT MAX (ROWID) FROM employees)

 /

7. To Check table has any data

 select count(*) from employees

Or select 1 from employees

where Rownum=1


8. How to find out table name for which this constraint  applied

sql> select owner_table-name from user_constraints
where constraints_name =<<your constraint_name>>

if you have access to the dba_constraints
sql> select owner_table-name from dba_constraints
where constraints_name =<<your constraint_name>>

9. How to get list of all tables in Oracle

sql> select owner,table_name from all_tables
NOte:- If you are only concerned with tablesthat you own,not those that you have access to, you could use user_table.
/
sql> select owner,table_name from user_tables
 

10.1. How can you convert a number into words using Oracle Sql Query?

Please see the query below:-

SELECT TO_CHAR (TO_DATE (523, 'j'), 'jsp') from dual


Output:
TO_CHAR(TO_DATE(523,'J'),
-------------------------
five hundred twenty-three