Package org.h2.expression
Class Expression
- java.lang.Object
-
- org.h2.expression.Expression
-
- Direct Known Subclasses:
Alias
,ArrayConstructorByQuery
,Condition
,DataAnalysisOperation
,ExpressionColumn
,ExpressionList
,Function0_1
,JavaFunction
,Operation0
,Operation1
,Operation1_2
,Operation2
,OperationN
,SimpleCase
,Subquery
,Wildcard
public abstract class Expression extends java.lang.Object implements HasSQL, Typed
An expression is a operation, a value, or a function in a query.
-
-
Field Summary
Fields Modifier and Type Field Description private boolean
addedToFilter
static int
AUTO_PARENTHESES
Wrap expression in parentheses only if it can't be safely included into other expressions without them.static int
MAP_IN_AGGREGATE
State for expressions inside an aggregate formapColumns(ColumnResolver, int, int)
.static int
MAP_IN_WINDOW
State for expressions inside a window function formapColumns(ColumnResolver, int, int)
.static int
MAP_INITIAL
Initial state formapColumns(ColumnResolver, int, int)
.static int
WITH_PARENTHESES
Wrap expression in parentheses unconditionally.static int
WITHOUT_PARENTHESES
Do not wrap expression in 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 Description Expression()
-
Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method 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.java.lang.String
getAlias(SessionLocal session, int columnIndex)
Get the alias name of a column or SQL expression if it is not an aliased expression.boolean
getBooleanValue(SessionLocal session)
Get the value in form of a boolean expression.java.lang.String
getColumnName(SessionLocal session, int columnIndex)
Get the column name or alias name of this expression.java.lang.String
getColumnNameForView(SessionLocal session, int columnIndex)
Get the column name of this expression for a view.abstract int
getCost()
Estimate the cost to process the expression.java.lang.StringBuilder
getEnclosedSQL(java.lang.StringBuilder builder, int sqlFlags)
Get the SQL statement of this expression.Expression
getNonAliasExpression()
Returns the main expression, skipping aliases.Expression
getNotIfPossible(SessionLocal session)
If it is possible, return the negated expression.int
getNullable()
Check whether this expression is a column and can store NULL.java.lang.String
getSchemaName()
Get the schema name, or nulljava.lang.String
getSQL(int sqlFlags)
Get the SQL statement of this expression.java.lang.String
getSQL(int sqlFlags, int parentheses)
Get the SQL statement of this expression.java.lang.StringBuilder
getSQL(java.lang.StringBuilder builder, int sqlFlags)
Appends the SQL statement of this object to the specified builder.java.lang.StringBuilder
getSQL(java.lang.StringBuilder builder, int sqlFlags, int parentheses)
Get the SQL statement of this expression.Expression
getSubexpression(int index)
Returns subexpression with specified index.int
getSubexpressionCount()
Returns count of subexpressions.java.lang.String
getTableAlias()
Get the table alias name or null if this expression does not represent a column.java.lang.String
getTableName()
Get the table name, or nullabstract TypeInfo
getType()
Returns the data type.abstract java.lang.StringBuilder
getUnenclosedSQL(java.lang.StringBuilder builder, int sqlFlags)
Get the SQL statement of this expression.abstract Value
getValue(SessionLocal session)
Return the resulting value for the current row.java.lang.StringBuilder
getWhenSQL(java.lang.StringBuilder builder, int sqlFlags)
Appends the SQL statement of this when operand to the specified builder.boolean
getWhenValue(SessionLocal session, Value left)
Return the resulting value of when operand for the current row.boolean
isConstant()
Check if this expression will always return the same value.abstract boolean
isEverything(ExpressionVisitor visitor)
Check if this expression and all sub-expressions can fulfill a criteria.boolean
isIdentity()
Check if this is an identity column.boolean
isNullConstant()
Check if this expression will always return the NULL value.boolean
isValueSet()
Is the value of a parameter set.boolean
isWhenConditionOperand()
Returns whether this expression is a right side of condition in a when operand.abstract 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.abstract Expression
optimize(SessionLocal session)
Try to optimize the expression.Expression
optimizeCondition(SessionLocal session)
Try to optimize or remove the condition.abstract void
setEvaluatable(TableFilter tableFilter, boolean value)
Tell the expression columns whether the table filter can return values now.java.lang.String
toString()
Convert this expression to a String.abstract void
updateAggregate(SessionLocal session, int stage)
Update an aggregate value.static java.lang.StringBuilder
writeExpressions(java.lang.StringBuilder builder, java.util.List<? extends Expression> expressions, int sqlFlags)
Get the SQL snippet for a list of expressions.static java.lang.StringBuilder
writeExpressions(java.lang.StringBuilder builder, Expression[] expressions, int sqlFlags)
Get the SQL snippet for an array of expressions.-
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
-
-
-
-
Field Detail
-
MAP_INITIAL
public static final int MAP_INITIAL
Initial state formapColumns(ColumnResolver, int, int)
.- See Also:
- Constant Field Values
-
MAP_IN_WINDOW
public static final int MAP_IN_WINDOW
State for expressions inside a window function formapColumns(ColumnResolver, int, int)
.- See Also:
- Constant Field Values
-
MAP_IN_AGGREGATE
public static final int MAP_IN_AGGREGATE
State for expressions inside an aggregate formapColumns(ColumnResolver, int, int)
.- See Also:
- Constant Field Values
-
AUTO_PARENTHESES
public static final int AUTO_PARENTHESES
Wrap expression in parentheses only if it can't be safely included into other expressions without them.- See Also:
- Constant Field Values
-
WITH_PARENTHESES
public static final int WITH_PARENTHESES
Wrap expression in parentheses unconditionally.- See Also:
- Constant Field Values
-
WITHOUT_PARENTHESES
public static final int WITHOUT_PARENTHESES
Do not wrap expression in parentheses.- See Also:
- Constant Field Values
-
addedToFilter
private boolean addedToFilter
-
-
Method Detail
-
writeExpressions
public static java.lang.StringBuilder writeExpressions(java.lang.StringBuilder builder, java.util.List<? extends Expression> expressions, int sqlFlags)
Get the SQL snippet for a list of expressions.- Parameters:
builder
- the builder to append the SQL toexpressions
- the list of expressionssqlFlags
- formatting flags- Returns:
- the specified string builder
-
writeExpressions
public static java.lang.StringBuilder writeExpressions(java.lang.StringBuilder builder, Expression[] expressions, int sqlFlags)
Get the SQL snippet for an array of expressions.- Parameters:
builder
- the builder to append the SQL toexpressions
- the list of expressionssqlFlags
- formatting flags- Returns:
- the specified string builder
-
getValue
public abstract Value getValue(SessionLocal session)
Return the resulting value for the current row.- Parameters:
session
- the session- Returns:
- the result
-
getType
public abstract TypeInfo getType()
Returns the data type. The data type may be unknown before the optimization phase.
-
mapColumns
public abstract void mapColumns(ColumnResolver resolver, int level, int state)
Map the columns of the resolver to expression columns.- Parameters:
resolver
- the column resolverlevel
- the subquery nesting levelstate
- current state for nesting checks, initial value isMAP_INITIAL
-
optimize
public abstract Expression optimize(SessionLocal session)
Try to optimize the expression.- Parameters:
session
- the session- Returns:
- the optimized expression
-
optimizeCondition
public final Expression optimizeCondition(SessionLocal session)
Try to optimize or remove the condition.- Parameters:
session
- the session- Returns:
- the optimized condition, or
null
-
setEvaluatable
public abstract void setEvaluatable(TableFilter tableFilter, boolean value)
Tell the expression columns whether the table filter can return values now. This is used when optimizing the query.- Parameters:
tableFilter
- the table filtervalue
- true if the table filter can return value
-
getSQL
public final java.lang.String getSQL(int sqlFlags)
Description copied from interface:HasSQL
Get the SQL statement of this expression. This may not always be the original SQL statement, specially after optimization.
-
getSQL
public final java.lang.StringBuilder getSQL(java.lang.StringBuilder builder, int sqlFlags)
Description copied from interface:HasSQL
Appends the SQL statement of this object to the specified builder.
-
getSQL
public final java.lang.String getSQL(int sqlFlags, int parentheses)
Get the SQL statement of this expression. This may not always be the original SQL statement, especially after optimization.- Parameters:
sqlFlags
- formatting flagsparentheses
- parentheses mode- Returns:
- the SQL statement
-
getSQL
public final java.lang.StringBuilder getSQL(java.lang.StringBuilder builder, int sqlFlags, int parentheses)
Get the SQL statement of this expression. This may not always be the original SQL statement, especially after optimization.- Parameters:
builder
- string buildersqlFlags
- formatting flagsparentheses
- parentheses mode- Returns:
- the specified string builder
-
needParentheses
public boolean needParentheses()
Returns whether this expressions needs to be wrapped in parentheses when it is used as an argument of other expressions.- Returns:
true
if it is
-
getEnclosedSQL
public final java.lang.StringBuilder getEnclosedSQL(java.lang.StringBuilder builder, int sqlFlags)
Get the SQL statement of this expression. This may not always be the original SQL statement, especially after optimization. Enclosing '(' and ')' are always appended.- Parameters:
builder
- string buildersqlFlags
- formatting flags- Returns:
- the specified string builder
-
getUnenclosedSQL
public abstract java.lang.StringBuilder getUnenclosedSQL(java.lang.StringBuilder builder, int sqlFlags)
Get the SQL statement of this expression. This may not always be the original SQL statement, especially after optimization. Enclosing '(' and ')' are never appended.- Parameters:
builder
- string buildersqlFlags
- formatting flags- Returns:
- the specified string builder
-
updateAggregate
public abstract void updateAggregate(SessionLocal session, int stage)
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.- Parameters:
session
- the sessionstage
- select stage
-
isEverything
public abstract boolean isEverything(ExpressionVisitor visitor)
Check if this expression and all sub-expressions can fulfill a criteria. If any part returns false, the result is false.- Parameters:
visitor
- the visitor- Returns:
- if the criteria can be fulfilled
-
getCost
public abstract int getCost()
Estimate the cost to process the expression. Used when optimizing the query, to calculate the query plan with the lowest estimated cost.- Returns:
- the estimated cost
-
getNotIfPossible
public Expression getNotIfPossible(SessionLocal session)
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.- Parameters:
session
- the session- Returns:
- the negated expression, or null
-
isConstant
public boolean isConstant()
Check if this expression will always return the same value.- Returns:
- if the expression is constant
-
isNullConstant
public boolean isNullConstant()
Check if this expression will always return the NULL value.- Returns:
- if the expression is constant NULL value
-
isValueSet
public boolean isValueSet()
Is the value of a parameter set.- Returns:
- true if set
-
isIdentity
public boolean isIdentity()
Check if this is an identity column.- Returns:
- true if it is an identity column
-
getBooleanValue
public boolean getBooleanValue(SessionLocal session)
Get the value in form of a boolean expression. Returns true or false. In this database, everything can be a condition.- Parameters:
session
- the session- Returns:
- the result
-
createIndexConditions
public void createIndexConditions(SessionLocal session, TableFilter filter)
Create index conditions if possible and attach them to the table filter.- Parameters:
session
- the sessionfilter
- the table filter
-
getColumnName
public java.lang.String getColumnName(SessionLocal session, int columnIndex)
Get the column name or alias name of this expression.- Parameters:
session
- the sessioncolumnIndex
- 0-based column index- Returns:
- the column name
-
getSchemaName
public java.lang.String getSchemaName()
Get the schema name, or null- Returns:
- the schema name
-
getTableName
public java.lang.String getTableName()
Get the table name, or null- Returns:
- the table name
-
getNullable
public int getNullable()
Check whether this expression is a column and can store NULL.- Returns:
- whether NULL is allowed
-
getTableAlias
public java.lang.String getTableAlias()
Get the table alias name or null if this expression does not represent a column.- Returns:
- the table alias name
-
getAlias
public java.lang.String getAlias(SessionLocal session, int columnIndex)
Get the alias name of a column or SQL expression if it is not an aliased expression.- Parameters:
session
- the sessioncolumnIndex
- 0-based column index- Returns:
- the alias name
-
getColumnNameForView
public java.lang.String getColumnNameForView(SessionLocal session, int columnIndex)
Get the column name of this expression for a view.- Parameters:
session
- the sessioncolumnIndex
- 0-based column index- Returns:
- the column name for a view
-
getNonAliasExpression
public Expression getNonAliasExpression()
Returns the main expression, skipping aliases.- Returns:
- the expression
-
addFilterConditions
public void addFilterConditions(TableFilter filter)
Add conditions to a table filter if they can be evaluated.- Parameters:
filter
- the table filter
-
toString
public java.lang.String toString()
Convert this expression to a String.- Overrides:
toString
in classjava.lang.Object
- Returns:
- the string representation
-
getSubexpressionCount
public int getSubexpressionCount()
Returns count of subexpressions.- Returns:
- count of subexpressions
-
getSubexpression
public Expression getSubexpression(int index)
Returns subexpression with specified index.- Parameters:
index
- 0-based index- Returns:
- subexpression with specified index, may be null
- Throws:
java.lang.IndexOutOfBoundsException
- if specified index is not valid
-
getWhenValue
public boolean getWhenValue(SessionLocal session, Value left)
Return the resulting value of when operand for the current row.- Parameters:
session
- the sessionleft
- value on the left side- Returns:
- the result
-
getWhenSQL
public java.lang.StringBuilder getWhenSQL(java.lang.StringBuilder builder, int sqlFlags)
Appends the SQL statement of this when operand to the specified builder.- Parameters:
builder
- string buildersqlFlags
- formatting flags- Returns:
- the specified string builder
-
isWhenConditionOperand
public boolean isWhenConditionOperand()
Returns whether this expression is a right side of condition in a when operand.- Returns:
true
if it is,false
otherwise
-
-