최신 1Z0-909 무료덤프 - Oracle MySQL 8.0 Database Developer

문제1

Which two statements are true about aggregate functions?

A. SUM () returns o if there are no rows to aggregate.

B. MIN () cannot use distinct when it executes as a Windows function.

C. COUNT (distinct) returns a count of the number of rows with different values including Null.

D. MAX () returns null if there are no rows to aggregate.

E. AVG () does not allow use of the distinct option.

정답: E

문제2

Examine the output:

Which explain command will obtain the output?

A. EXPLAIN PARTITIONS

B. EXPLAIN ANALYZE

C. EXPLAIN FORMAT=TREE

D. EXPLAIN PORMAT^TRADITIONAL

E. EXPLAIN PORMAT=JSON

정답: E

문제3

Examine these commands which execute successfully in the sequence shown in Sessions S1 and S2:

Now, examine this statement that execute successfully in s1:
S1> SELECT * FROM emp;
Which is true about the result of the select statement?

A. The inserted row is not returned because the isolation level is READ COMMITTED in S2.

B. The inserted row is returned because the transaction is auto committed in S2.

C. The inserted row is not returned because the transaction still active in s2.

D. The inserted row is returned because the isolation level is RPEATABLE READ in S1.

정답: C

문제4

You must reclaim memory used by a prepared statement named prep. Which two achieve this?

A. DROP PROCEDURE prep;

B. SET @prep = NULL;

C. DEALLOCATE PREPARE prep?

D. SET @a = ''; EXECUTE prep USING @a;

E. PREPARE prep FROM '';

F. DROP PREPARE prep;

정답: A,B

문제5

Examine this statement which executes successfully:
CREATE TABLE 'fshop' ('product' JSON DEFAULT NULL ) ENGINE=InnoDB;
Now, examine a json value contained in the table:
{"name" : "orange", "varieties" : [{"VarietyName":"Clementine", "Origin" : ["PA", "BU"] }, {"VarietyName": "tangerine", "Origin" : ["CH","JP"]>]> Which will cause documents to be indexed over the 'name' key?

A. ALTER TABLE fshop ADD COLUMN name VARCHAR(100) AS (product->' S - varieties' ) VIRTUAL, ADD KEY idx_name (name) ;

B. ALTER TABLE fshop ADD COLUMN name VARCHAR(20) AS (product-
>* S .varieties. VarietyName ' ) VIRTUAL, ADD KEY idx_name (name.) ;

C. ALTER TABLE fshop ADD COLUMN name VARCHAR(20) AS (product->' S - name' ) VIRTUAL, ADD KEY idx_name (name) ;

D. ALTER TABLE fshop ADD COLUMN name VARCHAR(20), ADD KEY idx_name (name) ;

E. ALTER TABLE fshop ADD name VARCHAR(20) AS (JSON_ONQUOTE (product->"S.varieties.VarietyName")), ADD INDEX (name);

정답: A

문제6

Examine the appointments table definition which contains one million rows:

Now, examine this statement which executes successfully:

Which statement will improve query performance?

A. ALTER TABLE appointments add index IX_1(credit,payment)

B. ALTER TABLE appointments add index IX_4<attendant_id, payment, credit)

C. ALTER TABLE appointments add index IX_2(attendant_session_id, created_by)

D. ALTER TABLE appointments add index IX_3(attendant_id, created_by)

정답: B

문제7

You must write a statement that combines the first_name and last_name columns from the employees table as "last_name, first_name." Which two statements will do this?

A. SELECT CONCAT_WS(', ',last_name,first_name) FROM employees;

B. SELECT GROUP_CONCAT(last_name, first_name) FROM employees;

C. SELECT CONCAT(last name,', ',first_name) FROM employees;

D. SELECT last_name, ' , ',first_name FROM employees;

E. SELECT last_name + ', ' + first_name FROM employees;

정답: A,C

최신 1Z0-909 무료덤프 - Oracle MySQL 8.0 Database Developer

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