%��������� Database Management Systems, R. Ramakrishnan 2 Relational Calculus Comes in two flavours: Tuple relational calculus (TRC) and Domain relational calculus (DRC). A drc query is safe if and only if it is domain-independent, i.e., the result of the query is determined solely by the data in the database, Domain Relational Calculus . �ZR+��3$?Рy��c�=�pd��+�`�!�@ A domain relational calculus (drc) query is a database query which uses the mathematical set notation to enumerate the result based on the data in the database. These are . endobj 5 0 obj 2 0 obj It is x�p\Ǖ6ژ�I� `3&. Projectable form of QBE Examples in lecture I. /Cs2 14 0 R >> /Font << /TT2.0 17 0 R /TT1.0 11 0 R >> /XObject << /Im4 18 0 R 4 0 obj The Domain Relational Calculus (1/2) Differs from tuple calculus in type of variables used in formulas Variables range over single values from domains of attributes Formula is made up of atoms Evaluate to either TRUE or FALSE for a specific set of values Domain Relational Calculus provides only the description of the query but it does not provide the methods to solve it. 2. �@*��*� << /Length 5 0 R /Filter /FlateDecode >> Tuple Relational Calculus. • T.AoperS.B where T,S are tuple variables and A,B are attribute names, oper is a comparison operator. %PDF-1.3 Both use variables in formulating predicates, but they use them in different ways. DatabaseSchemaUsedinExamples RespEmp DeptNo ProjNo EmPTime Project EmEnDate Emp_Act EmpNo MajProj MidInit LastName Employee WorkDept HireDate Salary FirstName EmpNo DeptName MgrNo AdmrDept DeptNo Department ProjNo ActNo EmStDate CS 348 Relational Calculus Fall 2012 2 / 14 ! stream Table: Student. Relational calculus is just the explanative way of telling the query. H�C��eY>�C@-���`p����%1{���P��?o�Ն���1�U��5̴�e0��q2Kr�!�di��u�֠S#�/��K-���Cl��'��d���h.&erG�%:v��ݕ�ײ�枽0�v�^����b�u��*�����)]�^����\m.�?W:i] There are two types of relational calculus – Tuple Relational Calculus (TRC) and Domain Relational Calculus (DRC). stream endstream %��������� 1. �`m ��!ذ��JU1��j_��t#��>����_n`��$��. Domain relational calculus uses the same operators as tuple calculus. endobj 3.5 Relational Calculus ... Domain : a pool of legal values. Calculus has variables, constants, comparison ops, … In the tuple relational calculus, variables represent tuples, and predicates are … TRC: Variables range over (i.e., get bound to) tuples. The relational calculus is a non-procedural formal query language. There are two types of relational calculus Tuple Relational Calculus (TRC) and Domain Relational Calculus (DRC). true /ColorSpace 21 0 R /Intent /Perceptual /SMask 22 0 R /BitsPerComponent �oRa�h�iW_Lb%���tDULaCgK(
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��Z� 4 0 obj << /ColorSpace 14 0 R /ShadingType 2 /Coords [ 4572000 0 4572000 6858000 ] CMPT 354: Database I -- Relational Calculus 14 Domain Relational Calculus • A nonprocedural query language equivalent in power to the tuple relational calculus – Each query is an expression of the form {

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