Relational Data Bases
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Relational Data Bases - Marcador
Relational Data Bases - Detalles
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Preguntas:
25 preguntas
| 🇬🇧 | 🇬🇧 |
| Table Joins | Cross Inner / Natural Outer( Left Right Full) |
| Table Joins | Cross Inner / Natural Outer( Left Right Full) |
| Table Joins | Cross Inner / Natural Outer( Left Right Full) |
| Entity Type | Thing about which data is kept |
| ATTRIBUTE | Property of entity |
| INSTANCE | An occurrence of an entity type |
| IDENTIFIER | Attribute that uniquely identifies an instance |
| • TABLE/RELATION | Representation of an entity |
| FIELD/COLUMN | Representation of an attribute |
| RECORD/ROW | Represents an instance |
| KEY | Represents an identifier |
| Relationship | Joins tables |
| Field value | Assigned to a field |
| Data type | Kind of data stored in field |
| Foreign key – | Key from one table added to second table to create relationship |
| Database | An organized collection of data |
| Database Management Systems (DBMS) I | A software system that stores, manages, and facilitates access to one or more databases. E.g. Oracle, MS Access, SQL Server, SQLite, mySQL PostgreSQL |
| Schema | Collection of objects in a database e.g. tables, views, indexes |
| JOIN | To select data from more than one table vvvv |
| Benefits of Relational Data Base | Reduces data duplication ,Improves integrity ,Facilitates querying Facilitates access contro |
| Create database | CREATE DATABASE dbasename CREATE TABLE tablename ( Col1 type col2 type … ); *Constraints may be added to columns e.g. PRIMARY KEY, CHECK, FOREIGN KE |
| Drop Database | DROP DATABASE dbasename; DROP TABLE tablename; |
| Alter | ALTER TABLE tablename ADD col type; DROP COLUMN colname ; MODIFY COLUMN colname type; |
| Insert into | INSERT INTO tablename (col1, col2, col3, …) VALUES (v1, v2, V3, …), (v1, v2, v3, …), (V1, V2, V3, …), …; |
| Database update | UPDATE tablename SET col = value WHERE rowfilter; *Note the omitting the WHERE clause will cause all rows to be updated |
| Select | SELECT col1, col2, col3, expr1, … FROM tablename WHERE rowfilter ORDER BY column LIMIT count OFFSET offset GROUP BY column HAViNG groupfilter; -SELECT * to select all columns WHERE, ORDER BY, LIMIT, GROUP BY, HAVING are all optional clauses |
| Delete | DELETE FROM tablename WHERE rowfilter; |
| Table Joins | Cross Inner / Natural Outer( Left Right Full) |