Package uk.ac.ed.epcc.webapp.jdbc.expr

This package contains logic for accessing expressions over values from objects/records.

See: Description

Interface Summary

Interface	Description
Accessor<T,R>	Interface that encodes data access operation on a target object.
DateSQLExpression	A Date valued SQLExpression where the underlying representation is really a numeric value.
FilterProvider<T,D>	An object that can attempt provide an explicit SQL filter for its property.
GroupingSQLValue<T>	A variant of SQLValue which is legal to use for group-by clauses.
IndexedSQLValue<T,I extends DataObject>	A SQLValue that generates a IndexedReference to a remote table.
NestedSQLValue<T,N>	A SQLValue that wraps a different one It includes default methods to handle any nested GroupingSQLValue.
SQLAccessor<T,R>	A combination of Accessor and SQLValue.
SQLExpression<T>	An object that can produce a SQL expression suitable for use in a select statement.
SQLValue<T>	An object that can create a value from a SQL fragment.
WrappedSQLExpression<T>	A SQLExpression which can be implemented more directly as a SQLValue for example type conversion performed in SQL When these are just being evaluated at the top level of the query a SQLValue can be substituted that performs some of the expression in jave.

Class Summary

Class	Description
AliasSQLValue<T>	A SQLValue decorator that adds an alias name to an SQL expression.
ArrayFuncExpression<F,T>
ArrayFuncValue<F,T>	A SQLValue that selects one of a set of values under control of an ArrayFunc (e.g.
AverageMapMapper<K>	A MapMapper where the data field is Numerical data averaged out.
AverageValueSQLValue	A SQLValue that generates an AverageValue from a combination of a sum SQLValue and a count field.
BinaryExpression	A binary numerical SQLExpression There is a factory method for generating these that can implement simple simplifications.
BinarySQLValue	a numerical binary SQLValue.
CaseExpression<X,R>	Combines SQLExpressions as a CASE statement.
CaseExpression.Clause<T,V>	encode one clause of the expression
CastDoubleSQLExpression<N extends java.lang.Number>	A SQLExpression that interprets a numeric SQLExpression to as a double.
CastLongSQLExpression<N extends java.lang.Number>	A SQLExpression that interprets a numeric SQLExpression to as a long.
CompareSQLExpression<C extends java.lang.Comparable>	A SQLExpression for the comparison of two values;
CompareSQLValue<C extends java.lang.Comparable>
CompositeIndexedSQLValue<H extends DataObject,I extends DataObject,T extends DataObject>	A IndexedSQLValue that extends through a join
ConcatSQLExpression	Combine multiple SQLExpression by concatenation in SQL.
ConstExpression<T,R>	A constant value SQLAccessor
CountDistinctExpression<T>	SQLExpression that counts distinct values of an expression.
CountDistinctMapMapper<K>	A MapMapper where the data field is Numerical data combined by countign distinct values As the key is a SQLValue rather than a SQLExpression we may have multiple SQL rows mapping to the same key so numerical results may have to be combined.
DateDerefSQLExpression<H extends DataObject,R extends DataObject>
DateSQLValue	A SQLValue that converts a millisecond value into a Date.
DerefSQLExpression<H extends DataObject,R extends DataObject,T>	A join based SQLExpression for accessing remote tables.
DistinctCountSQLValue	A SQLValue that generates an DistinctCount This is intended to be used in group by queries in conjunction with a group-by clause on the nested GroupingSQLValue.
DistinctMapper<D>	Generate a DistinctCount for a SQLValue
DoubleConvertSQLValue<T>	SQLAccessor that converts an SQLAccessor of a different type to a double
DurationSecondConvertSQLValue	SQLValue that converts a Duration into seconds
FuncExpression<T,D>	A SQLExpression that applies a SQLFunc to and inner SQLExpression.
GeneralMapMapper<K,R>	SQLGroupMapper to populate a Map from a SQL query.
IntConvertAccessor<T,R>
IntConvertSQLValue<T>	SQLValue that converts an SQLValue of a different type to an integer Note that this will prevent SQL filtering.
LabellerSQLValue<T,R>
LengthExpression	SQLExpression to generate the length of String SQLExpression.
LocateSQLExpression	Create locate expression in SQL.
LocateSQLValue	Create locate expression in SQL.
LongConvertSQLValue<T>	SQLValue that converts an SQLValue of a different type to an integer Note that this will prevent SQL filtering.
MapMapper<K,R>	SQLGroupMapper to populate a Map from a SQL query where the key and data are single target values.
MaximumDateMapMapper<K>	A MapMapper where the data field is Numerical that the maximum is selected from.
MaximumMapMapper<K>	A MapMapper where the data field is Numerical that the maximum is selected from.
MillisecondAccessor<R>
MillisecondSQLValue	A SQLValue that extracts the millisecond value from Date SQLExpression
MinimumDateMapMapper<K>	A MapMapper where the data field is Numerical that the minimum is selected from.
MinimumMapMapper<K>	A MapMapper where the data field is Numerical that the minimum is selected from.
MysqlDateConverter	convert a numeric SQLExpression to a DateSQLExpression
MysqlMillisecondConverter	Convert a date field to milliseconds
MysqlSQLHashExpression
MysqlTimestampDiffExpr	A MYSQL specific SQLExpression for the difference between two Date valued expressions.
PostgresqlDateConverter
PostgresqlMillisecondConverter	Convert a date field to milliseconds
ReductionMapper<R>	A ResultMapper that maps a single SQL reduction to a value of the same type
RemoteSQLValue<H extends DataObject,R extends DataObject,T>	Abstract superclass for a SQLValue that needs to follow a remote reference to access its data.
RoundSQLExpression<N extends java.lang.Number>	A SQLExpression that rounds an numeric SQLExpression to the nearest integer.
SelectAccessor<T,R>
SQLExpressionFilter<T,V>	A SQLFilter that compares a SQLExpression to a constant value.
SQLExpressionMatchFilter<T,V>	A SQLFilter that compares two SQLExpressions.
SQLExpressionNullFilter<T,V>	A SQLFilter that compares a SQLExpression to null.
SQLExpressionOrderClause<T>	Use a SQLExpression as an OrderClause Note this does not include any required filter needed by the SQLExpression
SQLExpressionOrderFilter<I,T>	An OrderFilter implemented directly using SQLExpressions.
SQLGroupMapper<O>	A base class for ResultMappers that use SQL Group-By queries there are methods to add various select clauses to the target string.
SQLSelectValue<T>	A SQLValue that returns the first non null result from a set of SQLValues
SQLValuePatternTransform	A SQLValue that maps regexp patterns to canonical strings.
StringConvertAccessor<T,R>	A Accessor that converts the result of a nested Accessor to a string.
StringConvertSQLExpression<T>	SQLExpression that converts an SQLExpression of a different type to a string
StringConvertSQLValue<T>	SQLValue that converts an SQLValue of a different type to a string
SumMapMapper<K>	A MapMapper where the data field is Numerical data combined by summation.
ValueResultMapper<O>	A resultMapper that returns a single value specified by a SQLValue

Enum Summary

Enum	Description
ArrayFunc	functions that can be applied to arrays of SQLExpressions.
Operator	A supported binary operators on Numbers in an expression
Reduction	Reduction operators.
SQLFunc	functions that can be applied to SQLExpressions.

Exception Summary

Exception	Description
CannotFilterException	Exception thrown when the requested Filter cannot be generated.
CombineException	Exception thrown on an illegal combine operation.
InvalidKeyException

Package uk.ac.ed.epcc.webapp.jdbc.expr Description

This package contains logic for accessing expressions over values from objects/records. There are 3 basic types:

• An Accessor that accesses a value from an object entirely in java
• A SQLValue that retrieves a value using SQL.
• A SQLExpression which is a SQLValue where the java representations corresponds directly to the SQL representation and so can be composed to form more complex expressions.

These allow the target clauses of complex queries to be built. The where clauses are handled by the filter classes some of which are also built out of SQLExpressions

Normally the SQLValue and SQLExpression interfaces are used to directly query the database. The Accessor interfaces provide the same functionality when records are retrieved as objects and queried individually.