PostgreSQL-CE PostgreSQL-CE-Certifications PGCES-02 Questions & Answers

• Question 131:

  Select the correct SQL statement which concatenates strings 'ABC' and 'abc' to form 'ABCabc'.

  A. SELECT 'ABC' . 'abc';

  B. SELECT cat('ABC', 'abc') FROM pg_operator;

  C. SELECT 'ABC' + 'abc';

  D. SELECT 'ABC' + 'abc' FROM pg_operator;

  E. SELECT 'ABC' || 'abc';

  Correct Answer: E

• Question 132:

  Select two correct descriptions about views.

  A. A view is created by 'DECLARE VIEW', and deleted by 'DROP VIEW'.

  B. A view is a virtual table which does not exist.

  C. A view is created to simplify complicated queries.

  D. You can create a view with the same name as already existing tables.

  E. A view only exists while the postmaster is running, and is deleted when the postmaster stops.

  Correct Answer: BC

• Question 133:

  Table "t1" is defined below.

  Table "t1" has a column "id" of type INTEGER, and a column "name" of type TEXT. t1:

  The following SQL is executed while client "A" is connected. BEGIN; SELECT * FROM t1 WHERE id = 2

  FOR UPDATE; SELECT * FROM t1 WHERE id = 1 FOR UPDATE; -- (*)

  While the second 'SELECT' statement, shown with (*), is being executed, a separate client "B" connects

  and executes the following SQL.

  Select the correct statement about the execution results. UPDATE t1 SET name = 'turtle' WHERE id = 2;

  Note: the default transaction isolation level is set to "read committed".

  A. The update process for client "B" is blocked until the current connection for client "A" is finished.

  B. The update process for client "B" is blocked until the current transaction for client "A" is finished.

  C. The 'UPDATE' process for client "B" proceeds regardless of the condition of client "A".

  D. The process of client "B" immediately generates an error.

  E. The processes for both clients are blocked, and an error stating that a deadlock has been detected is generated.

  Correct Answer: B

• Question 134:

  SQL statements were executed in the following order: CREATE TABLE fmaster (id INTEGER PRIMARY

  KEY, name TEXT); CREATE TABLE ftrans (id INTEGER REFERENCES fmaster (id), stat INTEGER, date

  DATE); INSERT INTO fmaster VALUES (1, 'itemA');

  INSERT INTO ftrans VALUES (1, 1, CURRENT_DATE);

  Select two SQL statements that will generate an error when executed next.

  A. INSERT INTO ftrans VALUES (1, 1, CURRENT_DATE);

  B. INSERT INTO ftrans VALUES (2, 1, '2007-07-07');

  C. UPDATE fmaster SET name = 'itemAX' WHERE id = 1;

  D. UPDATE fmaster SET id = 100 WHERE id = 1;

  E. UPDATE ftrans SET id = 200 WHERE id = 1;

  Correct Answer: AC

• Question 135:

  Select two suitable statements regarding the data types of PostgreSQL.

  A. One field can handle up to 1GB of data.

  B. 'n' in CHARACTER(n) represents the number of bytes.

  C. Only the INTEGER type can be declared as an array.

  D. There is a non-standard PostgreSQL data type, called Geometric data type, which handles 2dimensional data.

  E. A large object data type can be used to store data of unlimited size.

  Correct Answer: AD

• Question 136:

  The table "score" is defined as follows:

  gid | score -----+------1 | 70 1 | 60 2 | 100 3 | 80 3 | 50

  The following query was executed. Select the number of rows in the result. SELECT gid, max(score) FROM score GROUP BY gid HAVING max(score) > 60;

  A. 1 row

  B. 2 rows

  C. 3 rows

  D. 4 rows

  E. 5 rows

  Correct Answer: C

• Question 137:

  Table "t1" is defined as follows:

  CREATE TABLE t1 (value VARCHAR(5));

  A set of SQL statements were executed in the following order. Select the number of rows that table "t1"

  has after execution.

  BEGIN;

  INSERT INTO t1 VALUES ('AA'); SAVEPOINT point1;

  INSERT INTO t1 VALUES ('BB'); SAVEPOINT point2;

  INSERT INTO t1 VALUES ('CC'); ROLLBACK TO point1;

  INSERT INTO t1 VALUES ('DD'); END;

  A. 1 row

  B. 2 rows

  C. 3 rows

  D. 4 rows

  E. 0 rows

  Correct Answer: B

• Question 138:

  Select two suitable statements about sequences.

  A. A sequence always returns a 4-byte INTEGER type value, so the maximum value is 2147483647.

  B. A sequence is defined by 'CREATE SEQUENCE', and deleted by 'DROP SEQUENCE'.

  C. Although the "nextval" function is called during a transaction, it will have no effect if that transaction is rolled back.

  D. A sequence always generates 0 or consecutive positive numbers.

  E. A sequence number can be set by calling the "setval" function.

  Correct Answer: BE

• Question 139:

  Select two suitable statements regarding the following SQL statement: CREATE TRIGGER trigger_1 AFTER UPDATE ON sales FOR EACH ROW EXECUTE PROCEDURE write_log();

  A. It is defining a trigger "trigger_1".

  B. Every time 'UPDATE' is executed on the "sales" table, the "write_log" function is called once.

  C. The "write_log" function is called before 'UPDATE' takes place.

  D. 'UPDATE' is not executed if "write_log" returns NULL.

  E. 'DROP TRIGGER trigger_1 ON sales;' deletes the defined trigger.

  Correct Answer: AE

• Question 140:

  Select two transaction isolation levels supported in PostgreSQL.

  A. DIRTY READ

  B. READ COMMITTED

  C. REPEATABLE READ

  D. PHANTOM READ

  E. SERIALIZABLE

  Correct Answer: BE