SQL stands is an acronym which stands for Structured Query Language. SQL is a language that is used to manipulate and retrieve data from databases. A beginner's guide to SQL.
Standard statements for manipulating data with SQL
- SELECT
- UPDATE
- INSERT
- DELETE
- WHERE
RDMS stands for Relational Database Management System which is a type of database that stores data in tables, so it can be used in relation to other stored datasets
There are many types of `RDBMS` that can be used to manipulate data, For example, MySQL, MS Access, etc.
What are tables, columns, and rows?
A table is a collection of related data entries which consist of rows and columns. A row also called a record is an entity in a table. A column is an entity in a table that contains all information associated with a specific field in a table.
SQL syntax
SQL command (SELECT) followed by (*) operator which selects all the records from the table followed by (FROM) is a clause for selecting a particular table in a database. Lastly the name of the table. Note - SQL is not case sensitive but remembers the semicolon.
Create a table.
Use Create Database statement to create a new database.
Create a table in a database
Use the Create Table statement to create a table and what fields it should accept.
SELECT Statement
Selects all the records in the Location field (column) from the Employees table.
UPDATE Statement
update command is used to modify existing data in a table.
The example below makes changes to records in "ContactName" and "City" whose CustomerID is 1.
INSERT Statement
Insert command is used to insert new records in the table.
Inserts records into the Address field in the Customer table with the value Skagen 21.
DELETE Statement
Delete commands are used for deleting records in a table. Deletes record where the customer's name is Micheal Asiedu in the Customers table.
