This post is courtesy of the PL/SQL Challenge quiz ending 27 November 2015:
If a SELECT INTO statement without a BULK COLLECT clause returns multiple rows, PL/SQL raises the predefined exception TOO_MANY_ROWS and SQL%ROWCOUNT returns 1, not the actual number of rows that satisfy the query.
Furthermore, the value of SQL%ROWCOUNT attribute is unrelated to the state of a transaction. Therefore: When a transaction rolls back to a savepoint, the value of SQL%ROWCOUNT is not restored to the value it had before the save point. When an autonomous transaction ends, SQL%ROWCOUNT is not restored to the original value in the parent transaction.
Here's the code for the quiz - see how you do!
And of course sign up to take each weekly quiz as it is released (you can even compete for international rankings).
Static or embedded SQL are SQL statements that are written natively into your PL/SQL programs (as opposed to defining them as expressions for execution as dynamic SQL). An implicit cursor is a session cursor that is constructed and managed by PL/SQL. PL/SQL opens an implicit cursor every time you run a SELECT or DML statement. You cannot control an implicit cursor, but you can get information from its attributes. Oracle defines a number of attributes of implicit cursors, whose value can be obtained through the SQL%attribute syntax.
SQL%attribute always refers to the most recently run SELECT or DML statement. If no such statement has run, the value of SQL%attribute is NULL. An implicit cursor closes after its associated statement runs; however, its attribute values remain available until another SELECT or DML statement runs. The most recently run SELECT or DML statement might be in a different scope (another subprogram call that has now completed, for example).
To save an attribute value for later use, assign it to a local variable immediately. Otherwise, other operations, such as subprogram invocations, might change the value of the attribute before you can test it. SQL%ROWCOUNT returns NULL if no SELECT or DML statement has run. Otherwise, it returns the number of rows returned by a SELECT statement or affected by a DML statement (a PLS_INTEGER).
If a SELECT INTO statement without a BULK COLLECT clause returns multiple rows, PL/SQL raises the predefined exception TOO_MANY_ROWS and SQL%ROWCOUNT returns 1, not the actual number of rows that satisfy the query. Furthermore, the value of SQL%ROWCOUNT attribute is unrelated to the state of a transaction.
Therefore: When a transaction rolls back to a savepoint, the value of SQL%ROWCOUNT is not restored to the value it had before the save point. When an autonomous transaction ends, SQL%ROWCOUNT is not restored to the original value in the parent transaction.
If a SELECT INTO statement without a BULK COLLECT clause returns multiple rows, PL/SQL raises the predefined exception TOO_MANY_ROWS and SQL%ROWCOUNT returns 1, not the actual number of rows that satisfy the query.
Furthermore, the value of SQL%ROWCOUNT attribute is unrelated to the state of a transaction. Therefore: When a transaction rolls back to a savepoint, the value of SQL%ROWCOUNT is not restored to the value it had before the save point. When an autonomous transaction ends, SQL%ROWCOUNT is not restored to the original value in the parent transaction.
Here's the code for the quiz - see how you do!
And of course sign up to take each weekly quiz as it is released (you can even compete for international rankings).
I execute the following statements (which you can easily run yourself on LiveSQL):
Which of the choices result in "RC=1" being displayed on the screen after execution?
CREATE TABLE plch_flowers
(
id INTEGER PRIMARY KEY,
nm VARCHAR2 (100) UNIQUE
)
/
BEGIN
INSERT INTO plch_flowers
VALUES (1, 'Orchid');
INSERT INTO plch_flowers
VALUES (2, 'Rose');
COMMIT;
END;
/
Which of the choices result in "RC=1" being displayed on the screen after execution?
DECLARE
l_id INTEGER;
BEGIN
SELECT id
INTO l_id
FROM plch_flowers
WHERE nm = 'Orchid';
DBMS_OUTPUT.put_line ('RC=' || SQL%ROWCOUNT);
END;
/
DECLARE
l_id INTEGER;
BEGIN
SELECT id INTO l_id FROM plch_flowers;
EXCEPTION
WHEN OTHERS
THEN
DBMS_OUTPUT.put_line ('RC=' || SQL%ROWCOUNT);
END;
/
BEGIN
INSERT INTO plch_flowers
SELECT id * 3, UPPER (nm) FROM plch_flowers;
DBMS_OUTPUT.put_line ('RC=' || SQL%ROWCOUNT);
END;
/
DECLARE
l_id INTEGER;
BEGIN
INSERT INTO plch_flowers
VALUES (3, 'Tulip');
SAVEPOINT inserted_row;
INSERT INTO plch_flowers
VALUES (3, 'Lotus');
EXCEPTION
WHEN OTHERS
THEN
ROLLBACK TO inserted_row;
DBMS_OUTPUT.put_line ('RC=' || SQL%ROWCOUNT);
END;
/
DECLARE
l_id INTEGER;
PROCEDURE insert_and_save
IS
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
INSERT INTO plch_flowers
SELECT id * 3, UPPER (nm) FROM plch_flowers;
COMMIT;
END;
BEGIN
INSERT INTO plch_flowers
VALUES (10, 'Ambrosia');
insert_and_save;
DBMS_OUTPUT.put_line ('RC=' || SQL%ROWCOUNT);
END;
/
Background on SQL%ROWCOUNT
Static or embedded SQL are SQL statements that are written natively into your PL/SQL programs (as opposed to defining them as expressions for execution as dynamic SQL). An implicit cursor is a session cursor that is constructed and managed by PL/SQL. PL/SQL opens an implicit cursor every time you run a SELECT or DML statement. You cannot control an implicit cursor, but you can get information from its attributes. Oracle defines a number of attributes of implicit cursors, whose value can be obtained through the SQL%attribute syntax.
SQL%attribute always refers to the most recently run SELECT or DML statement. If no such statement has run, the value of SQL%attribute is NULL. An implicit cursor closes after its associated statement runs; however, its attribute values remain available until another SELECT or DML statement runs. The most recently run SELECT or DML statement might be in a different scope (another subprogram call that has now completed, for example).
To save an attribute value for later use, assign it to a local variable immediately. Otherwise, other operations, such as subprogram invocations, might change the value of the attribute before you can test it. SQL%ROWCOUNT returns NULL if no SELECT or DML statement has run. Otherwise, it returns the number of rows returned by a SELECT statement or affected by a DML statement (a PLS_INTEGER).
If a SELECT INTO statement without a BULK COLLECT clause returns multiple rows, PL/SQL raises the predefined exception TOO_MANY_ROWS and SQL%ROWCOUNT returns 1, not the actual number of rows that satisfy the query. Furthermore, the value of SQL%ROWCOUNT attribute is unrelated to the state of a transaction.
Therefore: When a transaction rolls back to a savepoint, the value of SQL%ROWCOUNT is not restored to the value it had before the save point. When an autonomous transaction ends, SQL%ROWCOUNT is not restored to the original value in the parent transaction.