Atchaya's Check Your Oracle Knowledge

You are running a pl/sql block or procedure called parent In that procedure you called another one procedure namely child and that procedure contains commit statement. After calling the child procedure the transactions done in parent procedure are also committed due to the child procedure commit statement. But you want to rollback or commit the parent procedure whole transactions based on your requirement after the calling procedure child. In this situation, you should add the "pragma autonomus transaction" in child procedure. If you add this statement then it acts as a separate. If you use commit in child procedure it will not affect the parent procedure. Example : CREATE OR REPLACE PROCEDURE parent() AS BEGIN UPDATE tab1 SET fieldname = value WHERE condition; UPDATE tab2 SET fieldname = value WHERE condition; child(); UPDATE tab4 SET fieldname = value WHERE condition; IF parentcondition COMMIT; ELSE ROLLBACK; END IF; END. CREATE OR REPLACE PROCEDURE child() AS PRAGMA AUTONO...

Suppose Database D1 contains 100 tables.. How 2 select the tables which are modified at 10am today? 1. SELECT table_name, table_owner FROM all_tab_modifications WHERE to_char(timestamp,'YYYYMMDDHH24MM') = to_char(sysdate,'YYYYMMDD')'1000' This will gives the table names which are modified (insert, update, delete, truncated) at 10 AM. 2. SELECT scn_to_timestamp(max(ora_rowscn)) FROM ;

How many number of rows, I can insert into a table simultaenously? Answer : Method 1: If you want to insert multiple rows with a single INSERT statement, you can use a subquery instead of the VALUES clause. Rows returned from the subquery will be inserted the target table. Example: INSERT INTO tablename1 SELECT fieldnamelist FROM tablename WHERE condition

The EMP table contains these columns: LAST NAME VARCHAR2(25) SALARY NUMBER(6,2) DEPARTMENT_ID NUMBER(6) You need to display the employees who have not been assigned to any department. You write the SELECT statement: SELECT LAST_NAME, SALARY, DEPARTMENT_ID FROM EMP WHERE DEPARTMENT_ID = NULL; What is true about this SQL statement? A. The SQL statement displays the desired results. B. The column in the WHERE clause should be changed to display the desired results. C. The operator in the WHERE clause should be changed to display the desired results. D. The WHERE clause should be changed to use an outer join to display the desired results. Answer: C Explanation: The operator in the WHERE clause should be changed to display the desired results. There are times when you want to substitute a value in place of NULL. Oracle provides this functionality with a special function, called NVL(). You can use operation equal with the keywords IS NULL, or you can achieve desired results using NVL() fu...

Examine the description of the STUDENTS table: STD_ID NUMBER(4) COURSE_ID VARCHARD2(10) START_DATE DATE END_DATE DATE Which two aggregate functions are valid on the START_DATE column? (Choose two) A. SUM(start_date) B. AVG(start_date) C. COUNT(start_date) D. AVG(start_date, end_date) E. MIN(start_date) F. MAXIMUM(start_date) Answer: C & E Explanation: It is possible to apply COUNT() and MIN() functions on the column with DATE data type. Incorrect Answers A: Function SUM() cannot be used with DATE data type column. B: Function AVG() cannot be used with DATE data type column. D: Function AVG() cannot be used with DATE data type column, and function AVG() just has one parameter X, not two. It averages all X column values returned by the SELECT statement. F: There is no MAXIMUM() function in Oracle, only MAX() function exists.

Examine the description of the EMPLOYEES table: EMP_ID NUMBER(4) NOT NULL LAST_NAME VARCHAR2(30) NOT NULL FIRST_NAME VARCHAR2(30) DEPT_ID NUMBER(2) JOB_CAT VARCHARD2(30) SALARY NUMBER(8,2) Which statement shows the maximum salary paid in each job category of each department? A.SELECT dept_id, job_cat, MAX(salary) FROM employees WHERE salary > MAX(salary); B.SELECT dept_id, job_cat, MAX(salary) FROM employees GROUP BY dept_id, job_cat; C. SELECT dept_id, job_cat, MAX(salary) FROM employees; D. SELECT dept_id, job_cat, MAX(salary) FROM employees GROUP BY dept_id; Answer: B Explanation: This answer provides correct syntax and semantics to show the maximum salary paid in each job category of each department. Incorrect Answers A: This query will not return any row because condition SALARY > MAX(SALARY) is FALSE. C: This query will return error because you cannot show maximum salary with DEPT_ID and JOB_CAT without grouping by these columns. D: The GROUP BY clause is missing JOB_ID col...

You are sorting data in a table in you SELECT statement in descending order. The column you are sorting on contains NULL records, where will the NULL record appears? A.At the beginning of the list. B.At the end of the list. C.In the middle of the list. D.At the same location they are listed in the unordered table. Answer: A Explanation: When sorting a column with null values in ascending order then the oracle places the Null values at the end of the list if the sorting is in descending order the oracle places the null values at the start of the list.