Databases

Alex Baine
Mind Map by Alex Baine, updated more than 1 year ago
Alex Baine
Created by Alex Baine over 6 years ago
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Description

This is a small mind map showing different queries and a bunch of questions i've encountered in tests

Resource summary

Databases
  1. Test
    1. Databases
      1. What is meant by the term 'database'
        1. A structured set of storage to hold data
        2. Difference between flat-file and relational
          1. Flat FIle
            1. Contains a single set of data, a table
            2. Relational
              1. Contains multiple tables connecting via foreign keys and primary keys
                1. Advantages
                  1. More organised, neater
                    1. Less physical storage needed
                2. DBMS
                  1. Describe what is meant by a DBMS
                    1. A database management system provides an interface for the user
                    2. A DBMS allows the separation of applications from the data. Why is this important?
                      1. If you want to change the structure it won't affect the data
                    3. Tables
                      1. Explain the relationship between entities and tables
                        1. An entity is a single person, place or thing where data can be stored
                        2. Explain the difference between a primary key and a foreign key
                          1. A primary key keeps the value unique while a foreign key connects 2 tables
                        3. Advantages of electronic database
                          1. You can search for a specific item
                            1. Takes up less physical room
                          2. SQL
                            1. Describe what is meant by SQL in regards to databases
                              1. Structured Query Language is a language used to query your databases. You can add items, delete items and also search for items.
                              2. Queries
                                1. Table name: Members | 14343 | Fiona | Gibson | GF6 3KL | 07722 235678
                                  1. Write an SQL statement to add this record to the database
                                    1. INSERT INTO 'Members' WHERE('ID','FirstName','LastName','PostCode','PhoneNo') VALUES (14343, 'Fiona', 'Gibson','GF63KL',07722235678);
                                    2. There has been a mistake in one of the data items in the table. Change the postcode to 'HF5 3SF'
                                      1. UPDATE 'Members' SET PostCode = 'HF5 3SF' WHERE PostCode = 'GF63KL';
                                      2. Extract all information in the FirstName and LastName fields
                                        1. SELECT * FROM 'Members' (FirstName, LastName);
                                  2. Validation, Verification and Data Integrity
                                    1. State what is meant by the following terms.
                                      1. Data Integrity
                                        1. The answer that is expected
                                        2. Validation
                                          1. Check if answer is reasonable
                                          2. Verification
                                            1. Check if data is true
                                          3. Describe the following methods of data validation
                                            1. Presence check
                                              1. Check if all information has been included
                                              2. Range check
                                                1. Check if answer exceeds maximum
                                                2. Format check
                                                  1. Check if answer matches the data type
                                            2. Queries
                                              1. SELECT * FROM table_name;
                                                1. Selects all data from 'table_name'
                                                2. INSERT INTO table_name VALUES (val1, val2);
                                                  1. Inserts values into 'table_name'
                                                  2. UPDATE 'table_name' SET column1 = "value" WHERE column1 != "value";
                                                    1. Update 'table_name' where column1 doesn't equal 'value' and set it to 'value'
                                                    2. DELETE FROM table_name WHERE column1 = "Delete me!";
                                                      1. Delete where column1 is equal to "Delete me!"
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