Package org.h2.expression
Class ValueExpression
- java.lang.Object
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- org.h2.expression.Expression
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- org.h2.expression.Operation0
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- org.h2.expression.ValueExpression
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- Direct Known Subclasses:
TypedValueExpression
public class ValueExpression extends Operation0
An expression representing a constant value.
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Field Summary
Fields Modifier and Type Field Description static ValueExpression
DEFAULT
This special expression represents the default value.static ValueExpression
FALSE
The expression represents ValueBoolean.FALSE.static ValueExpression
NULL
The expression represents ValueNull.INSTANCE.static ValueExpression
TRUE
The expression represents ValueBoolean.TRUE.(package private) Value
value
The value.-
Fields inherited from class org.h2.expression.Expression
AUTO_PARENTHESES, MAP_IN_AGGREGATE, MAP_IN_WINDOW, MAP_INITIAL, WITH_PARENTHESES, WITHOUT_PARENTHESES
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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
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Constructor Summary
Constructors Constructor Description ValueExpression(Value value)
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description void
createIndexConditions(SessionLocal session, TableFilter filter)
Create index conditions if possible and attach them to the table filter.static ValueExpression
get(Value value)
Create a new expression with the given value.static ValueExpression
getBoolean(boolean value)
Create a new expression with the given boolean value.static ValueExpression
getBoolean(Value value)
Create a new expression with the given boolean value.int
getCost()
Estimate the cost to process the expression.Expression
getNotIfPossible(SessionLocal session)
If it is possible, return the negated expression.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
isConstant()
Check if this expression will always return the same value.boolean
isEverything(ExpressionVisitor visitor)
Check if this expression and all sub-expressions can fulfill a criteria.boolean
isNullConstant()
Check if this expression will always return the NULL value.boolean
isValueSet()
Is the value of a parameter set.-
Methods inherited from class org.h2.expression.Operation0
mapColumns, optimize, setEvaluatable, updateAggregate
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Methods inherited from class org.h2.expression.Expression
addFilterConditions, getAlias, getBooleanValue, getColumnName, getColumnNameForView, getEnclosedSQL, getNonAliasExpression, getNullable, getSchemaName, getSQL, getSQL, getSQL, getSQL, getSubexpression, getSubexpressionCount, getTableAlias, getTableName, getWhenSQL, getWhenValue, isIdentity, isWhenConditionOperand, needParentheses, optimizeCondition, toString, writeExpressions, writeExpressions
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Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
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Methods inherited from interface org.h2.util.HasSQL
getTraceSQL
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Field Detail
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NULL
public static final ValueExpression NULL
The expression represents ValueNull.INSTANCE.
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DEFAULT
public static final ValueExpression DEFAULT
This special expression represents the default value. It is used for UPDATE statements of the form SET COLUMN = DEFAULT. The value is ValueNull.INSTANCE, but should never be accessed.
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TRUE
public static final ValueExpression TRUE
The expression represents ValueBoolean.TRUE.
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FALSE
public static final ValueExpression FALSE
The expression represents ValueBoolean.FALSE.
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value
final Value value
The value.
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Constructor Detail
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ValueExpression
ValueExpression(Value value)
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Method Detail
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get
public static ValueExpression get(Value value)
Create a new expression with the given value.- Parameters:
value
- the value- Returns:
- the expression
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getBoolean
public static ValueExpression getBoolean(Value value)
Create a new expression with the given boolean value.- Parameters:
value
- the boolean value- Returns:
- the expression
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getBoolean
public static ValueExpression getBoolean(boolean value)
Create a new expression with the given boolean value.- Parameters:
value
- the boolean value- Returns:
- the expression
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getValue
public Value getValue(SessionLocal session)
Description copied from class:Expression
Return the resulting value for the current row.- Specified by:
getValue
in classExpression
- Parameters:
session
- the session- Returns:
- the result
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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 interfaceTyped
- Specified by:
getType
in classExpression
- Returns:
- the data type
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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 classExpression
- Parameters:
session
- the sessionfilter
- the table filter
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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 classExpression
- Parameters:
session
- the session- Returns:
- the negated expression, or null
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isConstant
public boolean isConstant()
Description copied from class:Expression
Check if this expression will always return the same value.- Overrides:
isConstant
in classExpression
- Returns:
- if the expression is constant
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isNullConstant
public boolean isNullConstant()
Description copied from class:Expression
Check if this expression will always return the NULL value.- Overrides:
isNullConstant
in classExpression
- Returns:
- if the expression is constant NULL value
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isValueSet
public boolean isValueSet()
Description copied from class:Expression
Is the value of a parameter set.- Overrides:
isValueSet
in classExpression
- Returns:
- true if set
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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 classExpression
- Parameters:
builder
- string buildersqlFlags
- formatting flags- Returns:
- the specified string builder
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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 classExpression
- Parameters:
visitor
- the visitor- Returns:
- if the criteria can be fulfilled
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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 classExpression
- Returns:
- the estimated cost
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