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 The Architecture of Databases What is  The Architecture of Databases? -  The different components: Transport System, Query Processor, Execution Engine, and the Storage Engine. -   What purpose do each of these components serve. -  How do these components interact with each other. The Architecture of Databases Database Management Systems provide an abstraction that you can use in your applications for storing and (later) retrieving data. The DBMS exposes an API that you can use through some type of Query Language and it provides a set of guarantees on how you can store/retrieve your data from the database. A couple examples of guarantees are things like  durability  (you won’t lose your data if the database server crashes),  strong consistency  (for distributed databases - once you write some data to the database, all subsequent reads will return that value and you won’t get “stale” data) or read/write speeds ( IOPS  is the standard measure of input and output operations per second on

 The Important SQL Queries for Beginners 1. Retrieving Data From All Columns This is a very basic query to display all data from a table. Notice that this query only has one character after  SELECT : "*" (this denotes all columns). Therefore, you don't need to list the names of the columns. Of course, remember to write  FROM  and the name of the table from which you want to retrieve data. In this example, we are retrieving data from the table  animal . Code SELECT   * FROM   animal; 2. Retrieving Data From Certain Columns The query above displays all of the data from the table  animal . If you would like to only retrieve data from certain columns, list them after  SELECT . In this example, we are retrieving data from the  id  and  name  columns. Code SELECT   id,  name FROM   animal; 3. Filtering Data Using WHERE Clause In addition to retrieving data from certain columns, you can also filter data by listing conditions after  WHERE . In this example, there is one condition