To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) SQL cannot support object-orientation - This option is incorrect. SQL is a language specifically designed for managing and manipulating relational databases. While it may not have built-in support for object-oriented features, it can still interact with object-oriented programming languages through various mechanisms.

Option B) The same query can be written in many ways, each with vastly different execution plans - This option is correct. One of the major problems with SQL is that it allows for different ways to write the same query, and each variation can result in a different execution plan. This can lead to performance issues if the query is not optimized properly.

Option C) SQL syntax is too difficult for non-computer professionals to use - This option is incorrect. While SQL may have a learning curve, it is designed to be a declarative language that is relatively easy to understand and use. There are also graphical tools and user-friendly interfaces available that make it more accessible to non-computer professionals.

Option D) SQL creates excessive locks within the database - This option is incorrect. SQL does use locks to manage concurrent access to the database, but it does not inherently create excessive locks. The management of locks and concurrency control is the responsibility of the database management system (DBMS) implementing SQL.

Therefore, the correct answer is B) The same query can be written in many ways, each with vastly different execution plans. This option is correct because the flexibility of SQL can lead to different query variations, and if not optimized properly, it can result in vastly different execution plans with potential performance implications.

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To answer this question, you need to understand the features of relational databases and SQL. Let's go through each option to understand why it is correct or incorrect:

Option A) Independence of table relationships - This option is correct because one of the key features of relational databases is the ability to establish relationships between tables. This allows data to be stored in multiple tables and linked together using keys, providing flexibility and efficient data retrieval.

Option B) High speed of SQL - This option is incorrect because the speed of SQL queries can vary depending on factors such as the complexity of the query, the size of the database, and the efficiency of the database management system. While SQL can be optimized for performance, high speed is not an inherent feature of SQL itself.

Option C) Powerful GUI front-end - This option is incorrect because a GUI front-end is not an inherent feature of relational databases and SQL. While some database management systems may provide GUI tools for easier interaction with the database, the core functionality of SQL can be accessed through command-line interfaces or programming interfaces.

Option D) Easy to install and use - This option is incorrect because the ease of installation and use can vary depending on the specific database management system and the user's familiarity with SQL. While some database management systems may provide user-friendly installation processes and user interfaces, the ease of use is not an inherent feature of relational databases and SQL.

The correct answer is A) Independence of table relationships. This option is correct because the ability to establish relationships between tables is a fundamental feature of relational databases and SQL.

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To answer this question, you need to understand the different ways to restrict specific values from being inserted into a column in a table.

Option A) Index - This option is incorrect. An index is used to improve the performance of queries by creating a data structure that allows for faster data retrieval. It does not restrict specific values from being inserted into a column.

Option B) Check constraint - This option is incorrect. A check constraint is used to specify a condition that must be met for a column or set of columns in a table. It restricts the values that can be inserted into the column based on the specified condition.

Option C) Referential constraint - This option is incorrect. A referential constraint is used to enforce referential integrity between two tables. It ensures that values inserted into a foreign key column in one table exist in the referenced primary key column of another table.

Option D) Default constraint - This option is correct. A default constraint is used to specify a default value for a column in a table. It does not restrict specific values from being inserted into the column.

The correct answer is D) Default constraint. This option cannot be used to restrict specific values from being inserted into a column in a particular table.

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