org.h2.expression.condition

Class ConditionAndOrN

java.lang.Object

org.h2.expression.Expression

org.h2.expression.condition.ConditionAndOrN

All Implemented Interfaces:

HasSQL, Typed

public class ConditionAndOrN
extends Expression

An 'and' or 'or' condition as in WHERE ID=1 AND NAME=? with N operands. Mostly useful for optimisation and preventing stack overflow where generated SQL has tons of conditions.

Field Summary

Fields inherited from class org.h2.expression.Expression

AUTO_PARENTHESES, MAP_IN_AGGREGATE, MAP_IN_WINDOW, MAP_INITIAL, WITH_PARENTHESES, WITHOUT_PARENTHESES

Fields inherited from interface org.h2.util.HasSQL

ADD_PLAN_INFORMATION, DEFAULT_SQL_FLAGS, NO_CASTS, QUOTE_ONLY_WHEN_REQUIRED, REPLACE_LOBS_FOR_TRACE, TRACE_SQL_FLAGS

Constructor Summary

Constructors

Constructor and Description
ConditionAndOrN(int andOrType, Expression expr1, Expression expr2, Expression expr3)
ConditionAndOrN(int andOrType, java.util.List<Expression> expressions)

Method Summary

Modifier and Type	Method and Description
void	addFilterConditions(TableFilter filter) Add conditions to a table filter if they can be evaluated.
void	createIndexConditions(SessionLocal session, TableFilter filter) Create index conditions if possible and attach them to the table filter.
int	getCost() Estimate the cost to process the expression.
Expression	getNotIfPossible(SessionLocal session) If it is possible, return the negated expression.
Expression	getSubexpression(int index) Returns subexpression with specified index.
int	getSubexpressionCount() Returns count of subexpressions.
TypeInfo	getType() Returns the data type.
java.lang.StringBuilder	getUnenclosedSQL(java.lang.StringBuilder builder, int sqlFlags) Get the SQL statement of this expression.
Value	getValue(SessionLocal session) Return the resulting value for the current row.
boolean	isEverything(ExpressionVisitor visitor) Check if this expression and all sub-expressions can fulfill a criteria.
void	mapColumns(ColumnResolver resolver, int level, int state) Map the columns of the resolver to expression columns.
boolean	needParentheses() Returns whether this expressions needs to be wrapped in parentheses when it is used as an argument of other expressions.
Expression	optimize(SessionLocal session) Try to optimize the expression.
void	setEvaluatable(TableFilter tableFilter, boolean b) Tell the expression columns whether the table filter can return values now.
void	updateAggregate(SessionLocal session, int stage) Update an aggregate value.

Methods inherited from class org.h2.expression.Expression

getAlias, getBooleanValue, getColumnName, getColumnNameForView, getEnclosedSQL, getNonAliasExpression, getNullable, getSchemaName, getSQL, getSQL, getSQL, getSQL, getTableAlias, getTableName, getWhenSQL, getWhenValue, isConstant, isIdentity, isNullConstant, isValueSet, isWhenConditionOperand, optimizeCondition, toString, writeExpressions, writeExpressions

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.h2.util.HasSQL

getTraceSQL

Constructor Detail

ConditionAndOrN

public ConditionAndOrN(int andOrType,
                       Expression expr1,
                       Expression expr2,
                       Expression expr3)

ConditionAndOrN

public ConditionAndOrN(int andOrType,
                       java.util.List<Expression> expressions)

Method Detail

needParentheses

public boolean needParentheses()

Description copied from class: Expression

Returns whether this expressions needs to be wrapped in parentheses when it is used as an argument of other expressions.

Overrides:

needParentheses in class Expression

Returns:

true if it is

getUnenclosedSQL

public java.lang.StringBuilder getUnenclosedSQL(java.lang.StringBuilder builder,
                                                int sqlFlags)

Description copied from class: Expression

Get the SQL statement of this expression. This may not always be the original SQL statement, especially after optimization. Enclosing '(' and ')' are never appended.

Specified by:

getUnenclosedSQL in class Expression

Parameters:

builder - string builder

sqlFlags - formatting flags

Returns:

the specified string builder

createIndexConditions

public void createIndexConditions(SessionLocal session,
                                  TableFilter filter)

Description copied from class: Expression

Create index conditions if possible and attach them to the table filter.

Overrides:

createIndexConditions in class Expression

Parameters:

session - the session

filter - the table filter

getNotIfPossible

public Expression getNotIfPossible(SessionLocal session)

Description copied from class: Expression

If it is possible, return the negated expression. This is used to optimize NOT expressions: NOT ID>10 can be converted to ID<=10. Returns null if negating is not possible.

Overrides:

getNotIfPossible in class Expression

Parameters:

session - the session

Returns:

the negated expression, or null

getValue

public Value getValue(SessionLocal session)

Description copied from class: Expression

Return the resulting value for the current row.

Specified by:

getValue in class Expression

Parameters:

session - the session

Returns:

the result

optimize

public Expression optimize(SessionLocal session)

Description copied from class: Expression

Try to optimize the expression.

Specified by:

optimize in class Expression

Parameters:

session - the session

Returns:

the optimized expression

addFilterConditions

public void addFilterConditions(TableFilter filter)

Description copied from class: Expression

Add conditions to a table filter if they can be evaluated.

Overrides:

addFilterConditions in class Expression

Parameters:

filter - the table filter

mapColumns

public void mapColumns(ColumnResolver resolver,
                       int level,
                       int state)

Description copied from class: Expression

Map the columns of the resolver to expression columns.

Specified by:

mapColumns in class Expression

Parameters:

resolver - the column resolver

level - the subquery nesting level

state - current state for nesting checks, initial value is Expression.MAP_INITIAL

setEvaluatable

public void setEvaluatable(TableFilter tableFilter,
                           boolean b)

Description copied from class: Expression

Tell the expression columns whether the table filter can return values now. This is used when optimizing the query.

Specified by:

setEvaluatable in class Expression

Parameters:

tableFilter - the table filter

b - true if the table filter can return value

updateAggregate

public void updateAggregate(SessionLocal session,
                            int stage)

Description copied from class: Expression

Update an aggregate value. This method is called at statement execution time. It is usually called once for each row, but if the expression is used multiple times (for example in the column list, and as part of the HAVING expression) it is called multiple times - the row counter needs to be used to make sure the internal state is only updated once.

Specified by:

updateAggregate in class Expression

Parameters:

session - the session

stage - select stage

isEverything

public boolean isEverything(ExpressionVisitor visitor)

Description copied from class: Expression

Check if this expression and all sub-expressions can fulfill a criteria. If any part returns false, the result is false.

Specified by:

isEverything in class Expression

Parameters:

visitor - the visitor

Returns:

if the criteria can be fulfilled

getCost

public int getCost()

Description copied from class: Expression

Estimate the cost to process the expression. Used when optimizing the query, to calculate the query plan with the lowest estimated cost.

Specified by:

getCost in class Expression

Returns:

the estimated cost

getSubexpressionCount

public int getSubexpressionCount()

Description copied from class: Expression

Returns count of subexpressions.

Overrides:

getSubexpressionCount in class Expression

Returns:

count of subexpressions

getSubexpression

public Expression getSubexpression(int index)

Description copied from class: Expression

Returns subexpression with specified index.

Overrides:

getSubexpression in class Expression

Parameters:

index - 0-based index

Returns:

subexpression with specified index, may be null

getType

public TypeInfo getType()

Description copied from class: Expression

Returns the data type. The data type may be unknown before the optimization phase.

Specified by:

getType in interface Typed

Specified by:

getType in class Expression

Returns:

the data type