WGU - D426 Study Guide

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WGU - D426: Objective Assessment...

151 terms natesoundslike Preview WGU D 48 terms clsa Practice questions for this set Learn1 / 7Study using Learn Distributed Databases that share nothing Slow and unreliable Always run on a parallel system Database Management System (DBMS)software that helps business users interact with database systems Database Administrator (DBA)Secures database against unauthorized users AuthorizationDatabase systems authorize individual users Choose an answer

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query processorinterprets queries, creates a plan to modify the database or retrieve data, and returns query results to the application.Storage ManagerTranslates query processor's instructions into file-level data operations. Uses indexes to quickly location data.Transaction ManagerPrevents conflicts between transactions ISUD-INSERT -inserts rows -SELECT - retrieves data -UPDATE - modifies data -DELETE - deletes rows INTstores integers (whole numbers), without decimals, such as 123 or -123 DECIMALstores fractional numeric values VARCHARvalues with 0 to N characters DATEstores year, month, day AnalysisSpecification of database requirements-gathering info for database Database DesignProcess of determining and implementing database requirements. Covers 3

phases: Analysis, Logical design, Physical Design

Logical DesignImplementation of database as tables, keys, columns MySQL Command-Line Clienta text interface included in the MySQL Server download. MySQL Server returns an error code and description when an SQL statement is syntactically incorrect or the database cannot execute the statement.

Tupleordered set of values in parenthesis Ex: (a,b,c) or (c, b, a)

Table Synonymsfile, relation Row SynonymsRecord, Tuple ColumnField, Attribute Business Rulesbased on business policy and specific to a particular database Literals-Values that are string, numeric or binary -Strings must be surrounded by single or double quotes -Binary values are represented with x'0' where 0 is any hex value

Ex: 'String' or "String" or 123 or x'0fa2'

DDLData definition language - defines structure

CREATE, DROP, ALTER, TRUNCATE, RENAME

DQLData Query Language - retrieves data DMLData Manipulation Language - manipulates data stored in a database DCLData control language - control access to data DTLData Transaction Language - transaction management used to roll back changes Relational DatabaseA structured database containing tables that are related to each other Data independenceimprove query performance by changing the way data is organized without affecting query results CREATE TABLEA SQL command that creates a table; INT, VARCHAR, DATE, DECIMAL DROP TABLESQL command that deletes table ALTER TABLESQL command to add, delete, or modifu columns on table Data Typea named set of values, from which column values are drawn

Ex: Integer data types represent negative and positive integers

INT4 bytes of storage SMALLINT2 bytes TINYINT1 byte MEDIUMINT3 bytes BIGINT8 bytes % (modulo)Divides one numeric value by another and returns the integer remainder

5 % 2 = 1

^Raises one numeric value to the power of another

5^2 = 25

=Compares two values for equality

1=2 FALSE

!=Compares two values for inequality

1 != 2 TRUE

UPDATEuses the SET clause to specify the new column values; optional WHERE clause specifies which rows are updated. Omitting the WHERE clause results in all rows being updated.

DELETE

TRUNCATEdeletes all rows from table MERGEMerges data from one table (source) and inserts to another table (target) Primary KeyUsually table's first column; used to identify the row Simple Primary Keysingle column Composite Primary KeyMultiple columns Auto-increment Columnis a numeric column that is assigned an automatically incrementing value when a new row is inserted.Primary Key Errors-Inserting values for auto-increment primary keys -Omitting values for primary keys that are not auto-increment columns.-MySQL allows you to put any number for an auto increment column that is not a primary key. Overriding for a primary key will cause an error.Foreign KeyColumn or group of columns that refer to a primary key; data types must be same but names can be different Foreign Key Constraintadded to a CREATE TABLE statement; used to prevent actions that would destroy links between tables RESTRICTrejects an insert, update, or delete that violates referential integrity.CASCADEpropagates primary key changes to foreign keys Adding and Dropping ConstraintsConstraints are added and dropped with ALTER TABLE TableName followed by an ADD, DROP, or CHANGE clause BETWEENdetermine if value is between two other values value BETWEEN minValue AND maxValue and is equivalent to value >= minValue AND value <= maxValue.