Atchaya's Check Your Oracle Knowledge

Oracle - The self documenting dictionary Oracle's Data dictionary is itself self documenting. we can query DICTIONARY AND DICT_COLUMNS views for descriptions of the data dictionary views and their columns. The following query gives the descriptions of all of the data dictionary views. SELECT table_name, comments FROM dictionary ORDER BY table_name; It gives the large amount of output. By using where class we can focus a smaller set of views as like the following query. SELECT table_name, comments FROM dictionary WHERE table_name LIKE '%TABLE%' ORDER BY table_name It returns all views containing the word 'TABLE' Like wise We can query the DICT_COLUMNS view also. It gives the descriptions for the columns for all views. Following query retrieves descriptions for the columns in ALL_TAB_COLUMNS. SELECT column_name, comments FROM dict_columns WHERE table_name = 'ALL_TAB_COLUMNS'; This is a sample one. We can learn lot about oracle through data d...

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 STUDENT_GRADES table has these columns: STUDENT_ID NUMBER(12) SEMESTER_END DATE GPA NUMBER(4,3) The registrar has requested a report listing the students grade point averages (GPA), sorted from highest grade point average to lowest within each semester, starting from the earliest date. Which statement accomplishes this? A.SELECT student_id, semester_end, gpa FROM student_grades ORDER BY semester_end DESC, gpa DESC; B.SELECT student_id, semester_end, gpa FROM student_grades ORDER BY semester_end ASC, gpa ASC; C. SELECT student_id, semester_end, gpa FROM student_grades ORDER BY semester_end, gpa DESC; D. SELECT student_id, semester_end, gpa FROM student_grades ORDER BY gpa DESC, semester_end DESC; Answer :C Explanation: This answer shows correct syntax and semantics to receive desired result. Incorrect Answers A: Semesters will be sorted started from the oldest date, not the earliest. B: GPA data will be sorted in ascending order, what is opposite to our task. D: Semester...

Question 1. You need to display the last names of those employees who have the letter "A" as the second character in their names. Which SQL statement displays the required results? A. SELECT last_nameFROM EMPWHERE last_name LIKE '_A%'; B. SELECT last_nameFROM EMPWHERE last name ='*A%' C. SELECT last_nameFROM EMPWHERE last name ='_A%'; D. SELECT last_nameFROM EMPWHERE last name LIKE '*A%' Answer: A Explanation: Statement in this answer will show correct results because usage of operator LIKE and format mask '_A%' extract the last names of those employees who have the letter 'A' as the second character in their names. Symbol '_' in format mask substitute exactly one symbol and cannot be NULL. Incorrect Answers B: This statement will return only names starting from symbol '*'. It cannot be used as substitution symbol. C: Usage of equity operator here is not appropriate in this case: query will look exact for fi...