SQL explained
As defined by W3Schools, a world-renowned web developer site...
SQL (Structured Query Language) is a standard language for accessing and manipulating databases.
SQL is a coding language used to interact with databases through the use of queries.
Picture this: a doctor’s office with a filing cabinet in the left corner containing relevant information to the office’s operation.
The filing cabinet has 3 drawers: Appointments, Clients, and Staff.
Each drawer contains papers with the same required information on each paper.
For example, each paper in the Appointments drawer contains (1) the date and time of the appointment, (2) the name of the client, (3) the name of the doctor, and (4) a description of the appointment.
The main components of SQL are databases, tables, and records.
In comparison to the doctor's office, the filing cabinet is the database. Each drawer is a table. Each paper is a record.
"A doctor’s office with a filing cabinet containing relevant information to the office’s operation." This is the database.
"The filing cabinet has 3 drawers: Appointments, Clients, and Staff." These are the tables.
"Each drawer contains papers with the same required information on each paper." These are the records.
"For example, each paper in the Appointments drawer contains (1) the date and time of the appointment, (2) the name of the client, (3) the name of the doctor, and (4) a description of the appointment." These are the fields of the Appointments table. Fields are essentially the columns of information contained in a table.
Attributes are essential the specific values that each record contains corresponding to the table's fields.
Whenever an employee goes into the office to create, read, update, or delete information from the filing cabinet, they are executing a query.
Now that you've got a conceptual understanding of how SQL works, let's start coding! Click SELECT & FROM below to learn the core statements of any SQL query!
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 | Apply | PRACTICE SQL EXAM (PREVIEW ONLY) |
 | Tools | SQL Nerd Notes (PREVIEW ONLY) |
 | Concept | What is SQL? |
| Concept | SELECT & FROM |
| Concept | JOIN |
| Concept | WHERE (PREVIEW ONLY) |
| Concept | GROUP BY (PREVIEW ONLY) |
| Concept | HAVING (PREVIEW ONLY) |
| Concept | ORDER BY (PREVIEW ONLY) |
| Concept | Troubleshooting errors (PREVIEW ONLY) |
