Tag: databases

Questions Related to databases

A trigger belongs to…
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  1. a single table in the database

  2. to all tables in the database

  3. to all the tables of the user

  4. more than one table in the database

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Correct Option: B

The LIKE SQL keyword is used along with ...
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  1. ORDER BY clause.

  2. GROUP BY clause.

  3. JOIN clause.

  4. WHERE clause.

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Correct Option: D
Explanation:

To use the LIKE SQL keyword, the user needs to know that it is used for pattern matching in SQL queries. It is used to search for a specific pattern within a column of a table.

The correct answer is:

D. WHERE clause.

Explanation:

The LIKE keyword is used along with the WHERE clause to filter the results based on a specific pattern. The WHERE clause is used to extract only those records that fulfill a specified condition. The LIKE keyword is used to specify the pattern that the user wants to match.

A. ORDER BY clause: This clause is used to sort the results in ascending or descending order based on one or more columns of a table.

B. GROUP BY clause: This clause is used to group the results based on one or more columns of a table. It is typically used along with aggregate functions like SUM, COUNT, AVG, etc.

C. JOIN clause: This clause is used to combine two or more tables based on a related column between them.

D. WHERE clause: This clause is used to filter the results based on a specific condition. The LIKE keyword is used along with this clause to match a specific pattern within a column.

Therefore, option D is the correct answer.

Which of the following is a SQL aggregate function

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  1. join

  2. len

  3. left

  4. avg

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Correct Option: D

The JOIN is a SQL keyword used to ...

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  1. update database table

  2. verify that the inserted data is correct

  3. select data from 2 or more tables related by common attribute (table column).

  4. delete data from database table

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Correct Option: C

AI Explanation

To answer this question, you need to understand the concept of JOIN in SQL.

The JOIN keyword is used to select data from multiple tables that are related by a common attribute (table column). It allows you to combine rows from different tables based on their related values.

Let's go through each option to understand why it is correct or incorrect:

Option A) Update database table - This option is incorrect. The JOIN keyword is not used to update database tables. The UPDATE keyword is used for that purpose.

Option B) Verify that the inserted data is correct - This option is incorrect. The JOIN keyword is not used to verify the correctness of inserted data. Data validation is usually done using constraints, triggers, or other mechanisms.

Option C) Select data from 2 or more tables related by a common attribute (table column) - This option is correct. The JOIN keyword is used to combine rows from multiple tables based on a common attribute or column. It allows you to retrieve data from related tables in a single query.

Option D) Delete data from a database table - This option is incorrect. The JOIN keyword is not used to delete data from a database table. The DELETE keyword is used for that purpose.

The correct answer is Option C. This option is correct because the JOIN keyword is used to select data from multiple tables related by a common attribute (table column).

We refer to a join as a self-join when…
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  1. we are using left and right join together

  2. we are joining more than 2 tables

  3. we are joining table to itself

  4. when joining a table and its view

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Correct Option: C

The difference between the DELETE and TRUNCATE SQL clauses is:

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  1. The DELETE clause deletes all rows in a database table, while the TRUNCATE clause can have a WHERE condition and might or might not delete all rows in a table.

  2. The TRUNCATE clause is identical to the DELETE clause

  3. The TRUNCATE clause deletes all rows in a database table, while the DELETE clause can have a WHERE condition and might or might not delete all rows in a table.

  4. None fo the above

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Correct Option: C

What does the CREATE TABLE statement do?

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  1. Creates a database view

  2. Creates a new database table

  3. Creates a stored procedure

  4. Creates a trigger

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Correct Option: C

What is a trigger?

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  1. A trigger is part of data extraction process.

  2. A trigger is a special kind of stored procedures executed when certain event occurs.

  3. A trigger defines relations between tables.

  4. A trigger is a part of error handling

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Correct Option: C

What does follow after the SQL SELECT clause?

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  1. List of columns that will be selected or the * symbol.

  2. The JOIN SQL clause.

  3. The name of the table we are selecting from.

  4. Selects a database

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Correct Option: A

Which clause specifies conditions that determines the groups included in the query?

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  1. Having Clause

  2. Where clause

  3. Distinct

  4. Exists

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Correct Option: A