Package org.h2.expression
Class ExpressionColumn
java.lang.Object
org.h2.expression.Expression
org.h2.expression.ExpressionColumn
A column reference expression that represents a column of a table or view.
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate Column
private final String
private ColumnResolver
private final Database
private int
private final boolean
private final boolean
private final String
private final String
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
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Constructor Summary
ConstructorsConstructorDescriptionExpressionColumn
(Database database, String schemaName, String tableAlias) Creates a new instance of column reference for_ROWID_
column as normal expression.ExpressionColumn
(Database database, String schemaName, String tableAlias, String columnName) Creates a new instance of column reference for regular columns as normal expression.ExpressionColumn
(Database database, String schemaName, String tableAlias, String columnName, boolean quotedName) Creates a new instance of column reference for regular columns as normal expression.ExpressionColumn
(Database database, Column column) Creates a new column reference for metadata of queries; should not be used as normal expression. -
Method Summary
Modifier and TypeMethodDescriptionvoid
createIndexConditions
(SessionLocal session, TableFilter filter) Create index conditions if possible and attach them to the table filter.getAlias
(SessionLocal session, int columnIndex) Get the alias name of a column or SQL expression if it is not an aliased expression.getColumnException
(int code) Get exception to throw, with column and table info addedgetColumnName
(SessionLocal session, int columnIndex) Get the column name or alias name of this expression.getColumnNameForView
(SessionLocal session, int columnIndex) Get the column name of this expression for a view.int
getCost()
Estimate the cost to process the expression.getNotIfPossible
(SessionLocal session) If it is possible, return the negated expression.int
Check whether this expression is a column and can store NULL.Get the schema name, or nullGet the table name, or nullgetType()
Returns the data type.getUnenclosedSQL
(StringBuilder builder, int sqlFlags) Get the SQL statement of this expression.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.boolean
Check if this is an identity column.private void
mapColumn
(ColumnResolver resolver, Column col, int level) void
mapColumns
(ColumnResolver resolver, int level, int state) Map the columns of the resolver to expression columns.optimize
(SessionLocal session) Try to optimize the expression.private 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
addFilterConditions, getBooleanValue, getEnclosedSQL, getNonAliasExpression, getSQL, getSQL, getSQL, getSQL, getSubexpression, getSubexpressionCount, getTableAlias, getWhenSQL, getWhenValue, isConstant, isNullConstant, isValueSet, isWhenConditionOperand, needParentheses, 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
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Field Details
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database
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schemaName
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tableAlias
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columnName
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rowId
private final boolean rowId -
quotedName
private final boolean quotedName -
columnResolver
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queryLevel
private int queryLevel -
column
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Constructor Details
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ExpressionColumn
Creates a new column reference for metadata of queries; should not be used as normal expression.- Parameters:
database
- the databasecolumn
- the column
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ExpressionColumn
Creates a new instance of column reference for regular columns as normal expression.- Parameters:
database
- the databaseschemaName
- the schema name, ornull
tableAlias
- the table alias name, table name, ornull
columnName
- the column name
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ExpressionColumn
public ExpressionColumn(Database database, String schemaName, String tableAlias, String columnName, boolean quotedName) Creates a new instance of column reference for regular columns as normal expression.- Parameters:
database
- the databaseschemaName
- the schema name, ornull
tableAlias
- the table alias name, table name, ornull
columnName
- the column namequotedName
- whether name was quoted
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ExpressionColumn
Creates a new instance of column reference for_ROWID_
column as normal expression.- Parameters:
database
- the databaseschemaName
- the schema name, ornull
tableAlias
- the table alias name, table name, ornull
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Method Details
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getUnenclosedSQL
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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getTableFilter
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mapColumns
Description copied from class:Expression
Map the columns of the resolver to expression columns.- Specified by:
mapColumns
in classExpression
- Parameters:
resolver
- the column resolverlevel
- the subquery nesting levelstate
- current state for nesting checks, initial value isExpression.MAP_INITIAL
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mapColumn
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optimize
Description copied from class:Expression
Try to optimize the expression.- Specified by:
optimize
in classExpression
- Parameters:
session
- the session- Returns:
- the optimized expression
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optimizeOther
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getColumnException
Get exception to throw, with column and table info added- Parameters:
code
- SQL error code- Returns:
- DbException
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updateAggregate
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 classExpression
- Parameters:
session
- the sessionstage
- select stage
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getValue
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
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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setEvaluatable
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 classExpression
- Parameters:
tableFilter
- the table filterb
- true if the table filter can return value
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getColumn
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getOriginalColumnName
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getOriginalTableAliasName
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getColumnName
Description copied from class:Expression
Get the column name or alias name of this expression.- Overrides:
getColumnName
in classExpression
- Parameters:
session
- the sessioncolumnIndex
- 0-based column index- Returns:
- the column name
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getSchemaName
Description copied from class:Expression
Get the schema name, or null- Overrides:
getSchemaName
in classExpression
- Returns:
- the schema name
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getTableName
Description copied from class:Expression
Get the table name, or null- Overrides:
getTableName
in classExpression
- Returns:
- the table name
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getAlias
Description copied from class:Expression
Get the alias name of a column or SQL expression if it is not an aliased expression.- Overrides:
getAlias
in classExpression
- Parameters:
session
- the sessioncolumnIndex
- 0-based column index- Returns:
- the alias name
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getColumnNameForView
Description copied from class:Expression
Get the column name of this expression for a view.- Overrides:
getColumnNameForView
in classExpression
- Parameters:
session
- the sessioncolumnIndex
- 0-based column index- Returns:
- the column name for a view
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isIdentity
public boolean isIdentity()Description copied from class:Expression
Check if this is an identity column.- Overrides:
isIdentity
in classExpression
- Returns:
- true if it is an identity column
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getNullable
public int getNullable()Description copied from class:Expression
Check whether this expression is a column and can store NULL.- Overrides:
getNullable
in classExpression
- Returns:
- whether NULL is allowed
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isEverything
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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createIndexConditions
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
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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