Karteikarten
Databases
Karten in diesem Stapel (30)
- 1Flat fileAll data is stored in one table
- 20NFun-normalized database
- 3NormalizationProcess used to create relation databases with no repeating data
- 41NFA table that don't contain any repeating attributes
- 52NFA table is in second from if it is in first normal form and contain no partial dependencies (Must depends on the primary key)
- 63NFA table in third form if it is in second form and contains no non-key dependencies
- 7primary keyA unique key used to identify each record
- 8Foreign keysA table that contains two keys, they are both primary key from other tables, it is the foreign key on this third table
- 9Composite primary keyA mixture of two foreign keys
- 10Advantage of normalisation1. Easier to maintain and change a normalized table
2. No unnecessary duplication of data
3. Smaller table, so faster search and less storage required - 11SQLStructured Query Language
- 12SQL syntax statementSELECT
FROM
WHERE
BETWEEN
IN
ORDER BY - 13SemicolonSome database systems require a semicolon at the end of each SQL statement
- 14SELECTList of field to be display
- 15FROMlist table or the table where the data will come from
- 16WHERESearch for certain criteria
- 17ORDER BYList the field that the data is to be sorted on
- 18Creating tableCREATE TABLE tbltable
{
primarykey CHAR(4), NOT NULL, PRIMARY KEY
Description VARCHAR(8), NOT NULL
Cost CURRENCY
} - 19Float Date TimeFLOAT(10, 2)
Maximum of 10 digits and 2 decimals
DATE < #31/12/2018#
Date before 2019
TIME #10:5:19#
10 hours minutes and 19 seconds - 20Add new columnALTER TABLE tblProduct
ADD Grade CHAR(1) - 21Delete columnALTER TABLE tblProduct
DROP Grade - 22ModifyALTER TABLE tblProduct
MODIFY COLUMN description VARCHAR(4) - 23Inserting dataINSERT INTO Product (ProductID, Description) //Or write nothing for all column//
VALUES ("A435", "OMEGALUL") - 24Update dataUPDATE Product
SET Description = "Cable", Price = 3.00
WHERE ProductID = "A435" - 25DeleteDELETE FROM Product
WHERE ProductID = "A435" - 26DBMSDatabase Management System
- 27Advantages of a client-server systemConsistency of the database is maintained because only one copy is held.
Access rights and security are managed centrally. - 28Systems life cycleThe traditional approach is no longer considered the best approach to systems development because if any problem has been spotted, the cycle has to be restarted again, it takes too many time and resources
- 29Agile modeMore flexible and better suited to modern computer systems
- 30—
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- Beschreibung
- GCSE Computing Karteikarten am Databases, erstellt von Ho Ho am 15/02/2019.
- Erstellt von
- Ho Ho
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