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predicate - sqlconsider the declarative sentence-a proposition-that is used to introduce this topic student s1 named anne is enrolled on course
updating a variableassignment of an attribute value in a variable of a structured typesynatxset snc s2as in example the entire statement is
assignment source not a literal - variablesyntaxset sn sid substring snc from 1 for
assignment of variable - updating a variablesyntaxset sn sid s2this can obviously be read as set the variable sn to be equal in value to sid s2
adding table constraints alter table enrolment add constraint namenotnullcheck name is not null alter table enrolment add constraint
effect of anonymous columnsnow recall that a values expression denotes a table with undefined column names if an initial value is to be specified
creating a tablesyantaxcreate table enrolmentstudentid sidname varchar 30 not nullcourseid cidprimary key studentid courseid explanation
variable declaration - sqlsqls support for variables is very similar to tutorial ds except that the syntax for creating persistent variables-base
type versus representation confusion in sqlthis describes how a value might have two or more distinct representations for example user-defined type
third step at defining type sid in sqlcreate domain sid as varchar5check value is not null andsubstringvalue from 1 for 1 s andcastsubstringvalue
second step at defining type sid in sql create type sid as varchar5 explanation type sid announces that a type named sid is being defined to the
first step at defining type sid in sqlcreate type sid as c varchar5 explanation type sid announces that a type named sid is being defined to the
data types and representationsthis explains the concept possible representation abbreviated possrep and explains how these can be used in conjunction
effects of null in table literalwhen a values expression appears as the source value for an sql insert statement the key word null can appear as a
example of table literal - sqlexample a table literal correct versionvaluess1 c1 annes1 c2 annes2 c1 boriss3 c3 cindys4 c1 devindernow the question
table literals - sqlone might expect sql to support table literals in the manner illustrated in example 22 but in fact that is not a legal sql
multiset types - sqlan sql multiset is what in mathematics is also known as a bag-something like a set except that the same element can appear more
usefulness of data type in sql as in most computer languages a type can be used for constraining the values that are permitted to be used for some
data types in sql - xml array row binary large object for arbitrarily large bit strings xml for xml documents and fragments array types for arrays
data types in sql - interval booleaninterval for values denoting not intervals but durations in time such as 5 years 3 days 2 minutes and so
data types in sql - timestamptimestamp for values representing points in time on a specified uniform scale date is used for timestamps on a scale of
data types in sql - integerinteger or synonymously int for integers within a certain range sql additionally has types smallint and bigint for
data types in sql - decimaldecimal numeric real float and various other terms for various sets of rational numbers when these key words are specified
data types in sql - charactercharacter or synonymously char for character strings when this type is to be the declared type of something eg a column
data types in sqlsqls concept does not differ significantly from that defined in the theory book apart from that business concerning null however the