FREE Back-End Development MCQ Questions and Answers
A component of SQL used to access, and add the total number of records in a table can be obtained using an integrated aggregate function (will NOT ignore null values in columns) and remove data from databases.
Explanation:
DML (Data Manipulation Language) is a part of SQL that is used to query, insert, update, and remove data from a database. Examples of DML statements include SELECT (to query data), INSERT (to add new data), UPDATE (to modify existing data), and DELETE (to remove data).
An integrated function that changes a given value in the result set to a null.
Explanation:
The built-in function used to convert a specified value to null in the result set is NULLIF(). This function takes two arguments and returns null if the two arguments are equal; otherwise, it returns the first argument.
A broad view of a database showing all its tables and connections.
Explanation:
In database management systems, a schema is an overall view that represents the tables and relationships of an entire database. It provides a logical structure for organizing and displaying data in a database. A schema can be thought of as a blueprint or a plan for the database.
The total number of records in a table can be obtained using an integrated aggregate function (will NOT ignore null values in columns).
Explanation:
COUNT(*) is a built-in aggregate function in SQL that is used to return the total number of records in a table, including null values in the columns. The asterisk (*) is used to indicate that you want to count all the rows in the table.
A set of data spanning all rows in a table with the same datatype (records)
Explanation:
In a relational database, a column represents a set of data having the same data type in a table, spanning all rows or records. Each column in a table has a unique name and a specific data type, such as integer, string, date, etc.
A word or phrase used to specify which columns should be returned by a query
Explanation:
The SELECT keyword is used in SQL to specify which columns to retrieve in a query. It is followed by a comma-separated list of column names or expressions that define the data to be retrieved.
Contains two ID values and, if available, other details.
Explanation:
A linking table is a table in a relational database that contains two ID values from different tables and optionally additional information.