Tag: databases

Questions Related to databases

Syntax of Cursor declaration: Cursor <> as select * from <>;
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  1. True

  2. False

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Correct Option: B

Which of the following is not a schema object :
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  1. Indexes

  2. tables

  3. public synonyms

  4. triggers

  5. packages

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Correct Option: C

What is true of using group functions on columns that contain NULL Values
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  1. Group functions on columns ignore NULL values.

  2. Group functions on columns returning dates include NULL values

  3. Group functions on columns returning numbers include NULL values.

  4. Group functions on columns cannot be accurately used on columns that contain NULL values.

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Correct Option: A
Explanation:

To answer this question, the user needs to understand the behavior of group functions when used on columns that contain NULL values.

Option A is correct. Group functions ignore NULL values in columns. For example, the AVG function calculates the average of all non-NULL values, while the COUNT function counts all non-NULL values. This means that NULL values are not included in the calculation and do not affect the result.

Option B and Option C are incorrect because they describe the behavior of specific group functions, rather than the behavior of group functions in general. The behavior of each group function depends on the specific function being used and the data type of the column being aggregated.

Option D is incorrect because group functions can be accurately used on columns that contain NULL values. However, it is important to keep in mind that NULL values may affect the result of certain operations, such as the SUM function. If a column contains both NULL and non-NULL values, the SUM function will return a NULL value, unless the column is aggregated using the NVL function or a similar function that replaces NULL values with a default value.

Therefore, the correct answer is:

The Answer is: A. Group functions on columns ignore NULL values.

You cannot modify data in a view if it contains: Group functions such as SUM, MIN, MAX, AVG, … A GROUP BY clause. The DISTINCT keyword. Columns defined by expressions (i.e, SAL * 12). The ROWNUM pseudo column.
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  1. True

  2. False

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Correct Option: B

Which table should you query to determine when your procedure was last compiled?
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  1. USER_OBJECTS

  2. USER_PROCEDURES

  3. USER_PROCS

  4. USER_PLSQL_UNITS

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Correct Option: A

A transaction is a set of SQL statements between any two COMMIT and ROLLBACK statements
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  1. True

  2. False

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Correct Option: B

Which of the following syntax is correct for creating a proc
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  1. CREATE OR REPLACE PROCEDURE <> as

  2. CREATE OR REPLACE PROCEDURE <>(Parameter list) as

  3. CREATE OR REPLACE PROCEDURE <> is

  4. All of the above

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Correct Option: D

Choose correct statement below
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  1. When a parameter is passed as an IN variable it is passed by reference

  2. When variables are passed in OUT or INOUT mode it is pass by value

  3. The NOCOPY clause tells to PL/SQL engine to pass the variable by reference

  4. All of the above

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Correct Option: D

How can you migrate from a LONG to a LOB data type for a column?
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  1. Use the DBMS_MANAGE_LOB.MIGRATE procedure

  2. Use the UTL_MANAGE_LOB.MIGRATE procedure.

  3. Use the ALTER TABLE command

  4. You cannot migrate from a LONG to a LOB date type for a column

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Correct Option: C

You need to create a trigger on the EMP table that monitors every row that is changed and places this information into the AUDIT_TABLE. What type of trigger do you create?
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  1. FOR EACH ROW trigger on the EMP table.

  2. Statement-level trigger on the EMP table.

  3. FOR EACH ROW trigger on the AUDIT_TABLE table.

  4. Statement-level trigger on the AUDIT_TABLE table.

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Correct Option: A