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Database Articles
Page 182 of 546
End User Database
The end user is usually not concerned about the transaction or operations done at various levels and is only aware of the product which may be a software or an application. Therefore, this is a shared database which is specifically designed for the end user, just like different levels’ managers. Summary of whole information is collected in this database.
Read MoreOne-to-One Unary Relationship in DBMS
A One-to-One Unary Relationship is the association with the same entity between the same instances represented by same role group.Above figure represents a set of married persons with the relationship MARRIED_TO. Each person is married to only one and only one person in the group.In One-to-One Unary we have three cases available −Mandatory-MandatoryOptional-OptionalOptional-Mandatory or Mandatory-OptionalMandatory-MandatoryEach instance of the role group must fully participate in the relationship. In the above example a Person is married to one and only one Person.Optional-OptionalIn this case the participation of a instance within a role group is optional i.e. the participation is not mandatory.In the ...
Read MoreBinary Relationship in Database
A Binary Relationship is the relationship between two different Entities i.e. it is a relationship of role group of one entity with the role group of another entity.There are three types of cardinalities for Binary Relationships −1. One-to-One2. One-to-many3. Many-to-ManyOne-to-OneHere one role group of one entity is mapped to one role group of another entity. In simple terms one instance of one entity is mapped with only one instance of another entity.In this type the primary key of one entity must be available as foreign key in other entity.For example − consider two entities Person and Driver_License.Person has the information about ...
Read MoreEntity Relationship Participation in Database
In a Relationship, Participation constraint specifies the existence of an entity when it is related to another entity in a relationship type. It is also called minimum cardinality constraint.This constraint specifies the number of instances of an entity that can participate in a relationship type.There are two types of Participation constraint −Total ParticipationEach entity in the entity set is involved in at least one relationship in a relationship set i.e. the number of relationship in every entity is involved is greater than 0.Consider two entities Employee and Department related via Works_For relationship. Now, every Employee works in at least one ...
Read MoreRemote system allowed in SAP HANA Smart Data Access
In SAP HANA SPS07, it has been extended to MSSQL server and Oracle database and write operation was permitted to perform on remote data sources.Following remote systems are allowed under Smart Data Access with Write operation in SAP HANA SPS07 −SAP HANASybase ASESAP Sybase IQTeradata 13.0 or higherApache Hadoop 2.3MSSQL 11Oracle 12c
Read MoreUsing SAP HANA SPS06 vs SPS07 with Smart Data Access SDA
In below table, you can see the list of remote data sources that are supported under SAP HANA Smart Data Access for SPS06 and SPS07 and the operations supported −SAP HANA VersionsSPS06SPS07 or higherSupported Data Sources under Smart Data AccessSybase ASE, SAP Sybase IQ 15.4 ESD 3 and Version 16.0 Apache Hadoop Version 2.3 Teradata Database Version 13.0 or higherSybase ASE, SAP Sybase IQ 15.4 ESD 3 and Version 16.0 Apache Hadoop Version 2.3 Teradata Database Version 13.0 or higher Oracle database 12c MSSQL version 11 for SQL Server 2012 IBM DB2Operations SupportedSelectSelect, Insert, Update and Delete
Read MoreAdapters supported under Smart Data Access in SAP HANA
Below is the list of Adapters which are supported under Smart Data Access in SAP HANA −This comes while creating a new Remote Data Source.
Read MoreRDBMS terminologies
RDMS Terminologies include Database, Table, Columns, etc. Let us see them one by one −DatabaseDatabase is a collection of tables like , , etc.TableA table is a collection of rows and columns , for example, StudentIdStudentNameStudentRank052Tom1035David2077John3ColumnColumn is in a table −RowRow is also called a tuple in RDBMS. A relation in a database has rows and columns.Primary KeyEvery table has one Primary key and cannot have null values.For example, ProjectID is a primary key in Project Table, since it uniquely identifies the project:ProjectIDProjectNameP01Cluster Grouping SystemP02Hospital Management SystemForeign KeyIf you want to link two tables, use Foreign Key.For example, Employee table has DEPT_ID ...
Read MoreAlternate Key in RDBMS
Alternate Key or Secondary Key is the key that has not been selected to be the primary key, but are candidate keys. However, it is considered a candidate key for the primary key.A candidate key not selected as a primary key is called alternate or secondary key. Candidate key is an attribute or set of attributes that you can consider as a Primary key.Let us see an example −Student_IDStudent_EnrollStudent_NameStudent_Email0962717Manishaaa@gmail.com0552655Mananabc@gmail.com0672699Shreyaspqr@gmail.comAbove, Student_ID, Student_Enroll and Student_Email are the candidate keys. They are considered candidate keys since they can uniquely identify the student record. Select any one of the candidate key as the primary. Rest ...
Read MoreUnique Key in RDBMS
Many users consider Primary Key as Unique Key, since both uniquely identify a table, but Unique Key is different from Primary Key. Unique Key accepts null values and Primary Key cannot have null.Let us compare Primary Key and Unique Key and understand its concept −UsageA Unique Key is used to prevent duplicate values in a column. Primary Key provided uniqueness to a table.NULL ValuesA primary key cannot accept NULL values; this makes Primary Key different from Unique Key, since Unique Key allows one value as NULL value.VolumeA table can only have a single Primary Key, whereas a Unique Key can ...
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