A SELECT statement retrieves information from the database. Which of the following activities can be done using SELECT statement?
A SELECT statement retrieves information from the database. Which of the following activities can be done using SELECT statement?
The correct option is D All of these
A SELECT statement retrieves information
from the database. Selection, projection, join activities
can be done using SELECT statement.
The SQL SELECT statement returns
a result set of records from one or more tables. A SELECT statement retrieves
zero or more rows from one or more database tables or database views. In most
applications, SELECT is the most commonly used data query language (DQL) command.
Projection: A project operation selects
only certain columns (fields) from a table. The result table has a subset of
the available columns and can include anything from a single column to all
available columns.
Selection: A select operation selects a subset of rows
(records) in a table (relation) that satisfy a selection condition. The ability
to select rows from out of complete result set is called Selection. It involves
conditional filtering and data staging. The subset can range from no rows, if
none of the rows satisfy the selection condition, to all rows in a table.
Join:- A join operation combines data from two or more tables based on one or more
common column values. A join operation enables an information system user to
process the relationships that exist between tables. The join operation is very
powerful because it allows system users to investigate relationships among data
elements that might not be anticipated at the time that a database is designed.
A SELECT statement retrieves information from the database. Selection, projection, join activities can be done using SELECT statement.
The SQL SELECT statement returns a result set of records from one or more tables. A SELECT statement retrieves zero or more rows from one or more database tables or database views. In most applications, SELECT is the most commonly used data query language (DQL) command.
Projection: A project operation selects only certain columns (fields) from a table. The result table has a subset of the available columns and can include anything from a single column to all available columns.
Selection: A select operation selects a subset of rows (records) in a table (relation) that satisfy a selection condition. The ability to select rows from out of complete result set is called Selection. It involves conditional filtering and data staging. The subset can range from no rows, if none of the rows satisfy the selection condition, to all rows in a table.
Join:- A join operation combines data from two or more tables based on one or more common column values. A join operation enables an information system user to process the relationships that exist between tables. The join operation is very powerful because it allows system users to investigate relationships among data elements that might not be anticipated at the time that a database is designed.
