Practice Questions

<p class="ChallengerEditorTheme__paragraph_dark" dir="ltr" style="color: rgb(255,255,255);"><span style="white-space: pre-wrap;">A primary key in a relational database management system (RDBMS) is&nbsp;a column or set of columns that uniquely identifies each row in a table.&nbsp;A primary key is essential for the operations of an RDBMS, and it has many benefits, including :&nbsp;</span></p><ul class="ChallengerEditorTheme__ul_dark" style="color: rgb(255,255,255);"><li value="1" class="ChallengerEditorTheme__listItem_dark"><span style="white-space: pre-wrap;">Identifying unique data:&nbsp;A primary key ensures that each row in a table has a unique value.&nbsp;</span></li><li value="2" class="ChallengerEditorTheme__listItem_dark"><span style="white-space: pre-wrap;">Preventing duplicate records:&nbsp;A primary key prevents duplicate records from being entered into a table.&nbsp;</span></li><li value="3" class="ChallengerEditorTheme__listItem_dark"><span style="white-space: pre-wrap;">Setting up relationships between tables:&nbsp;A primary key can be used to implement relationships between tables in a database.&nbsp;</span></li><li value="4" class="ChallengerEditorTheme__listItem_dark"><span style="white-space: pre-wrap;">Ensuring fields aren't null:&nbsp;A primary key ensures that fields in a table aren't left empty.&nbsp;</span></li><li value="5" class="ChallengerEditorTheme__listItem_dark"><span style="white-space: pre-wrap;">Updating or deleting specific records:&nbsp;A primary key can be used to update or delete specific records in a table.&nbsp;</span></li><li value="6" class="ChallengerEditorTheme__listItem_dark"><span style="white-space: pre-wrap;">Ensuring row-level accessibility:&nbsp;A primary key ensures that each row in a table is accessible.&nbsp;</span></li></ul><p class="ChallengerEditorTheme__paragraph_dark" style="color: rgb(255,255,255);"><br></p><p class="ChallengerEditorTheme__paragraph_dark" style="text-align: start; color: rgb(255,255,255);"><br></p>

A primary key can contain multiple columns

A primary key is used only for joining multiple tables

DDL (Data Definition Language) is a type of SQL command used to define data structures and modify data. 
It creates, alters, and deletes database objects such as tables, views, indexes, and users. 
Examples of DDL statements include CREATE, ALTER, DROP and TRUNCATE

Internal Schema:

- Defines the physical storage structure of the database
- Describes how data is stored in files, indexes, and other data structures
- Specifies storage locations, access methods, and data compression techniques
- Managed by the Database Management System (DBMS)

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<li class="LGOjhe" role="heading" data-attrid="wa:/description" aria-level="3" data-hveid="CBwQAA"><span class="ILfuVd" lang="en"><span class="hgKElc">A compiler is&nbsp;<strong>a special program that translates a programming language's source code into machine code, bytecode or another programming language</strong>. </span></span></li>
<li class="LGOjhe" role="heading" data-attrid="wa:/description" aria-level="3" data-hveid="CBwQAA"><span class="ILfuVd" lang="en"><span class="hgKElc">The source code is typically written in a high-level, human-readable language such as Java or C++.</span></span></li>
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<li>The HTTP verbs comprise a major portion of our “uniform interface” constraint and provide us the action counterpart to the noun-based resource.</li>
<li>The primary or most-commonly-used HTTP verbs (or methods, as they are properly called) are POST, GET, PUT, PATCH, and DELETE.</li>
<li>These correspond to create, read, update, and delete (or CRUD) operations, respectively.</li>
<li>There are a number of other verbs, too, but are utilized less frequently.</li>
<li>Of those less-frequent methods, OPTIONS and HEAD are used more often than others.</li>
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