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list the string operations supported by sql1 pattern matching operation2 concatenation3 extracting character strings4 converting among uppercase and
define tuple variabletuple variables are used for comparing two tuples in the same relation the tuple variables are explained in the from clause by
what is the use of rename operationrename operation is used to rename both relations and an attributesit uses the as clause taking the formold-name
give the general form of sql queryselect a1 a2 anfrom r1 r2 rmwhere
what are the three classes of sql expressionsql expression consists of three
what are the categories of sql commandsql commands are separated in to the following categories1 data - definitition language2 data manipulation
what are the parts of sql languagethe sql language has various partsdata - definitition language data manipulation language view
what is foreign keya relation schema r1 derived from an er schema may contain among its attributes the primary key of another relation schema r2this
write short notes on schema diagrama database schema along with primary key and foreign key dependencies can be depicted pictorially by schema
write short notes on domain relational calculusthe domain relational calculus uses domain variables that take on values from an attribute domain
write short notes on tuple relational calculusthe tuple relational calculation is anon procedural query language it defines the desired information
what is a project operationthe project operation is a unary operation that returns its argument relation with particular attributes left out
what is a select operationthe select operation selects tuples that please a given predicate we use the lowercase letter sigma to denote
define- relational algebrathe relational algebra is a procedural query language it having of a set of operations that take one or two relation as
what is a super keya super key is a set of one or more attributes that collectively permits us to recognize uniquely an entity in the entity
what is a primary keyprimary key is chosen by the database designer as the principal means of identifying an entity in the entity
what is a candidate keyminimal super keys are known as candidate
define the term domainfor each n every attribute there is a set of permitted values known as the domain of that
define tuple variabletuple variable is a type of variable whose domain is the set of all
write short notes on relational modelthe relational model uses a collection of tables to show both data and the relationships between those data the
define the terms i ddl ii dmlddl data base schema is particular by a set of definitions expressed by a special language known as a data definition
explain the two types of participation constraint1 total the participation of an entity set e in a relationship set r is said to be total if each
what does the cardinality ratio specifymapping cardinalities or cardinality ratios state the number of entities to which another entity can be
define weak and strong entity setsweak entity set entity set that do not have key attribute of their own are known as weak entity setsstrong entity
define the terms i key attribute ii value set key attribute an entity type usually has an attribute whose values are exact from each individual