Database Mock Test - 2

In the EXIST operator, when a match is found, the query ends processing for that row. This means that if the condition specified in the EXISTS operator evaluates to true for a particular row, the query will stop processing that row and move on to the next row. This can be useful in optimizing queries and improving performance, as it allows the database to stop processing a row as soon as a match is found, rather than continuing to evaluate the condition for the remaining rows.

The statement is true because a Cartesian product is the result of a join operation where no specific matching columns are specified. In a Cartesian product, every row from one table is combined with every row from another table, resulting in a combination of all possible pairs of rows from both tables. This can be a very large result set and should be used with caution to avoid performance issues.

A positive value of SQL code typically indicates a successful execution. This means that the SQL statement was processed without any errors and the desired operation was completed successfully. It could mean that data was inserted, updated, or deleted successfully in the database, or that a query was executed and returned the expected results.

Group By does not do any sorting. This statement is true. When using the Group By clause in SQL, the result set is grouped based on the specified column(s), but it does not guarantee any specific order of the grouped data. The order of the groups or the rows within each group is not defined unless an additional sorting operation is applied, such as using the Order By clause. Therefore, Group By does not inherently perform any sorting.

A single bound DBRM with optimized access path refers to a package. A package is a compiled version of an application program that contains the optimized access path to the database. It is created after the BIND process, which binds the DBRM (Database Request Module) to create an executable module. The package is then stored in the database and can be reused by multiple application programs, saving compilation time and optimizing performance by using the already optimized access path.

A scalar function is a type of function that operates on a single value and returns a single value. In the context of the given statement, the scalar function is performed for each row in the result table. This means that the function is applied individually to each row in the table, producing a result specific to that row. This is different from aggregate functions, which operate on multiple rows and return a single result for the entire group. Group by is used to group rows together based on a common value, while aggregate functions calculate a single value for each group.

Automatic recompilation occurs when either an existing index is dropped or a new index is created. In both cases, the database management system automatically recompiles the affected queries to ensure that they continue to execute efficiently. This process is necessary because dropping an index can change the access path for queries, and creating a new index may provide a more efficient access path. Therefore, both scenarios trigger automatic recompilation to maintain optimal query performance.

The given statement "GRANT SELECT ON EMPTAB TO USER" is not a correct syntax. In SQL, the correct syntax for granting privileges is "GRANT privileges ON table TO user". Therefore, the correct syntax in this case would be "GRANT SELECT ON EMPTAB TO USER".