Definitions - 1.3 Exchanging Data 0.0 / 5 ? ComputingExchanging DataA2/A-levelOCR Created by: osymondsCreated on: 09-11-17 14:07 Lossy Compression All non-essential data is permanently removed 1 of 20 Lossless Compression Looks for repeated patterns to reduce the data held. No data is lost. Run-length or Dictionary compression. 2 of 20 Flat File Database One table database of a plain text file with one record per line 3 of 20 Primary Key Unique Identifier for a record 4 of 20 Secondary Key A unique identifier that is not the Primary key 5 of 20 Foreign Key Connects tables to each other 6 of 20 ACID Atomicity, Consistency, Isolation, Durability 7 of 20 Atomicity A transaction is processed in its entirety or not at all. 8 of 20 Consistency No validation rules are broken. 9 of 20 Isolation concurrent execution of transactions leads to the same result as if transactions were processed one after the other 10 of 20 Durability This ensures that once a transaction has been committed, it will remain so, even in the event of a power cut. 11 of 20 Dictionary Compression Look for repeated items or patters stored in a dictionary matrix with a set value and replace the repeated part with the value each time it comes up. 12 of 20 Run-Length Compression Look at repeated singular characters of colors. Store as a value and the number of times it turns up. 13 of 20 Alter Table - SQL ALTER TABLE tblProduct (/n) ADD QtyInStock INTEGER 14 of 20 Delete a Column - SQL ALTER TABLE tblProduct (/n) DROP QtyInStock 15 of 20 Change the Data Type of a Column - SQL ALTER TABLE tblProduct (/n) MODIFY COLUMN Description VARCHAR (30) NOT NULL 16 of 20 Insert new record - SQL ProductID CHAR(4) NOT NULL, PRIMARY KEY Description (/n) VARCHAR(20) NOT NULL Price (/n) CURRENCY 17 of 20 Insert new value - SQL INSERT INTO Product (ProductID, Description, Price) (/n) VALUES (“A345”, “Pink Rabbit”, 7.50) 18 of 20 Update a record - SQL UPDATE Product (/n) SET Description = “Blue Rabbit”, Price = 8.25 (/n) WHERE ProductID = “A345” 19 of 20 Delete an record - SQL DELETE FROM Product (/n) WHERE ProductID = “A345” 20 of 20
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