Class BaseColumnNode
- java.lang.Object
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- org.apache.derby.impl.sql.compile.QueryTreeNode
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- org.apache.derby.impl.sql.compile.ValueNode
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- org.apache.derby.impl.sql.compile.BaseColumnNode
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- All Implemented Interfaces:
Visitable
class BaseColumnNode extends ValueNode
A BaseColumnNode represents a column in a base table. The parser generates a BaseColumnNode for each column reference. A column refercence could be a column in a base table, a column in a view (which could expand into a complex expression), or a column in a subquery in the FROM clause. By the time we get to code generation, all BaseColumnNodes should stand only for columns in base tables.
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Field Summary
Fields Modifier and Type Field Description private java.lang.String
columnName
private TableName
tableName
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Fields inherited from class org.apache.derby.impl.sql.compile.ValueNode
transformed
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Fields inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode
AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_CYCLE, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX
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Constructor Summary
Constructors Constructor Description BaseColumnNode(java.lang.String columnName, TableName tableName, DataTypeDescriptor dtd, ContextManager cm)
Constructor for a referenced column name
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description (package private) void
acceptChildren(Visitor v)
Accept a visitor on all child nodes.(package private) void
generateExpression(ExpressionClassBuilder acb, MethodBuilder mb)
Do the code generation for this node.(package private) java.lang.String
getColumnName()
Get the name of this columnprotected int
getOrderableVariantType()
Return the variant type for the underlying expression.(package private) java.lang.String
getSchemaName()
Get the user-supplied schema name for this column's table.(package private) java.lang.String
getTableName()
Get the user-supplied table name of this column.(package private) boolean
isEquivalent(ValueNode o)
Tests if this node is equivalent to the specified ValueNode.java.lang.String
toString()
Convert this object to a String.-
Methods inherited from class org.apache.derby.impl.sql.compile.ValueNode
bindExpression, bindExpression, categorize, changeToCNF, checkIsBoolean, checkTopPredicatesForEqualsConditions, constantExpression, copyFields, eliminateNots, evaluateConstantExpressions, genEqualsFalseTree, generate, genIsNullTree, genSQLJavaSQLTree, getClone, getConstantValueAsObject, getDataValueFactory, getSourceResultColumn, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isCloneable, isConstantExpression, isInListProbeNode, isParameterNode, isRelationalOperator, isSameNodeKind, optimizableEqualityNode, preprocess, putAndsOnTop, remapColumnReferencesToExpressions, requiresTypeFromContext, selectivity, setCollationInfo, setCollationInfo, setCollationUsingCompilationSchema, setCollationUsingCompilationSchema, setNullability, setTransformed, setType, setType, setType, updatableByCursor, verifyChangeToCNF, verifyEliminateNots, verifyPutAndsOnTop
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Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode
accept, addTag, addUDTUsagePriv, addUDTUsagePriv, bindOffsetFetch, bindRowMultiSet, bindUserCatalogType, bindUserType, checkReliability, checkReliability, convertDefaultNode, copyTagsFrom, createTypeDependency, debugFlush, debugPrint, disablePrivilegeCollection, formatNodeString, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContext, getContextManager, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getLongProperty, getNullNode, getOffsetOrderedNodes, getOptimizerFactory, getOptimizerTracer, getParameterTypes, getSchemaDescriptor, getSchemaDescriptor, getStatementType, getTableDescriptor, getTypeCompiler, getUDTDesc, isAtomic, isPrivilegeCollectionRequired, isSessionSchema, isSessionSchema, makeConstantAction, makeTableName, makeTableName, nodeHeader, optimizerTracingIsOn, orReliability, parseSearchCondition, parseStatement, printLabel, printSubNodes, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setEndOffset, setRefActionInfo, stackPrint, taggedWith, treePrint, treePrint, verifyClassExist
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Field Detail
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columnName
private java.lang.String columnName
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tableName
private TableName tableName
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Constructor Detail
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BaseColumnNode
BaseColumnNode(java.lang.String columnName, TableName tableName, DataTypeDescriptor dtd, ContextManager cm) throws StandardException
Constructor for a referenced column name- Parameters:
columnName
- The name of the column being referencedtableName
- The qualification for the columndtd
- Data type descriptor for the columncm
- Context manager- Throws:
StandardException
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Method Detail
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toString
public java.lang.String toString()
Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.
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getColumnName
java.lang.String getColumnName()
Get the name of this column- Overrides:
getColumnName
in classValueNode
- Returns:
- The name of this column
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getTableName
java.lang.String getTableName()
Get the user-supplied table name of this column. This will be null if the user did not supply a name (for example, select a from t). The method will return B for this example, select b.a from t as b The method will return T for this example, select t.a from t- Overrides:
getTableName
in classValueNode
- Returns:
- The user-supplied name of this column. Null if no user- supplied name.
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getSchemaName
java.lang.String getSchemaName() throws StandardException
Get the user-supplied schema name for this column's table. This will be null if the user did not supply a name (for example, select t.a from t). Another example for null return value (for example, select b.a from t as b). But for following query select app.t.a from t, this will return APP- Overrides:
getSchemaName
in classValueNode
- Returns:
- The schema name for this column's table
- Throws:
StandardException
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generateExpression
void generateExpression(ExpressionClassBuilder acb, MethodBuilder mb) throws StandardException
Do the code generation for this node. Should never be called.- Overrides:
generateExpression
in classValueNode
- Parameters:
acb
- The ExpressionClassBuilder for the class being builtmb
- The method the code to place the code- Throws:
StandardException
- Thrown on error
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getOrderableVariantType
protected int getOrderableVariantType()
Return the variant type for the underlying expression. The variant type can be: VARIANT - variant within a scan (method calls and non-static field access) SCAN_INVARIANT - invariant within a scan (column references from outer tables) QUERY_INVARIANT - invariant within the life of a query (constant expressions)- Overrides:
getOrderableVariantType
in classValueNode
- Returns:
- The variant type for the underlying expression.
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isEquivalent
boolean isEquivalent(ValueNode o)
Tests if this node is equivalent to the specified ValueNode. Two ValueNodes are considered equivalent if they will evaluate to the same value during query execution.This method provides basic expression matching facility for the derived class of ValueNode and it is used by the language layer to compare the node structural form of the two expressions for equivalence at bind phase.
Note that it is not comparing the actual row values at runtime to produce a result; hence, when comparing SQL NULLs, they are considered to be equivalent and not unknown.
One usage case of this method in this context is to compare the select column expression against the group by expression to check if they are equivalent. e.g.:
SELECT c1+c2 FROM t1 GROUP BY c1+c2
In general, node equivalence is determined by the derived class of ValueNode. But they generally abide to the rules below:
- The two ValueNodes must be of the same node type to be considered equivalent. e.g.: CastNode vs. CastNode - equivalent (if their args also match), ColumnReference vs CastNode - not equivalent.
- If node P contains other ValueNode(s) and so on, those node(s) must also be of the same node type to be considered equivalent.
- If node P takes a parameter list, then the number of arguments and its arguments for the two nodes must also match to be considered equivalent. e.g.: CAST(c1 as INTEGER) vs CAST(c1 as SMALLINT), they are not equivalent.
- When comparing SQL NULLs in this context, they are considered to be equivalent.
- If this does not apply or it is determined that the two nodes are not equivalent then the derived class of this method should return false; otherwise, return true.
- Specified by:
isEquivalent
in classValueNode
- Parameters:
o
- the node to compare this ValueNode against.- Returns:
true
if the two nodes are equivalent,false
otherwise.
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acceptChildren
void acceptChildren(Visitor v) throws StandardException
Description copied from class:QueryTreeNode
Accept a visitor on all child nodes. All sub-classes that add fields that should be visited, should override this method and callaccept(v)
on all visitable fields, as well assuper.acceptChildren(v)
to make sure all visitable fields defined by the super-class are accepted too.- Overrides:
acceptChildren
in classQueryTreeNode
- Parameters:
v
- the visitor- Throws:
StandardException
- on errors raised by the visitor
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