java.lang.Object
org.apache.derby.impl.sql.compile.QueryTreeNode
org.apache.derby.impl.sql.compile.ValueNode
org.apache.derby.impl.sql.compile.CoalesceFunctionNode
- All Implemented Interfaces:
- org.apache.derby.iapi.sql.compile.Visitable
- public class CoalesceFunctionNode
- extends ValueNode
This node represents coalesce/value function which returns the first argument that is not null.
The arguments are evaluated in the order in which they are specified, and the result of the
function is the first argument that is not null. The result can be null only if all the arguments
can be null. The selected argument is converted, if necessary, to the attributes of the result.
SQL Reference Guide for DB2 has section titled "Rules for result data types" at the following url
http://publib.boulder.ibm.com/infocenter/db2help/index.jsp?topic=/com.ibm.db2.udb.doc/admin/r0008480.htm
I have constructed following table based on various tables and information under "Rules for result data types"
This table has FOR BIT DATA TYPES broken out into separate columns for clarity
Note that are few differences between Cloudscape and DB2
1)there are few differences between what datatypes are consdiered compatible
In DB2, CHAR FOR BIT DATA datatypes are compatible with CHAR datatypes
ie in addition to following table, CHAR is compatible with CHAR FOR BIT DATA, VARCHAR FOR BIT DATA and LONG VARCHAR FOR BIT DATA
ie in addition to following table, VARCHAR is compatible with CHAR FOR BIT DATA, VARCHAR FOR BIT DATA and LONG VARCHAR FOR BIT DATA
ie in addition to following table, LONG VARCHAR is compatible with CHAR FOR BIT DATA, VARCHAR FOR BIT DATA and LONG VARCHAR FOR BIT DATA
ie in addition to following table, CHAR FOR BIT DATA is compatible with DATE, TIME, TIMESTAMP
ie in addition to following table, VARCHAR FOR BIT DATA is compatible with DATE, TIME, TIMESTAMP
2)few datatypes donot have matching precision in Cloudscape and DB2
In DB2, precision of TIME is 8. In Cloudscape, precision of TIME is 0.
In DB2, precision,scale of TIMESTAMP is 26,6. In Cloudscape, precision of TIMESTAMP is 0,0.
In DB2, precision of DOUBLE is 15. In Cloudscape, precision of DOUBLE is 52.
In DB2, precision of REAL is 23. In Cloudscape, precision of REAL is 7.
In DB2, precision calculation equation is incorrect when we have int and decimal arguments.
The equation should be p=x+max(w-x,10) since precision of integer is 10 in both db2 and cloudscape. Instead, DB2 has p=x+max(w-x,11)
Types. S I B D R D C V L C V L C D T T B
M N I E E O H A O H A O L A I I L
A T G C A U A R N A R N O T M M O
L E I I L B R C G R C G B E E E B
L G N M L H V . H V S
I E T A E A A B A A T
N R L R R I R R A
T C T . . M
H B B P
A I I
R T T
SMALLINT { "SMALLINT", "INTEGER", "BIGINT", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
INTEGER { "INTEGER", "INTEGER", "BIGINT", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
BIGINT { "BIGINT", "BIGINT", "BIGINT", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
DECIMAL { "DECIMAL", "DECIMAL", "DECIMAL", "DECIMAL", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
REAL { "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "REAL", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
DOUBLE { "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "DOUBLE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
CHAR { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "CHAR", "VARCHAR", "LONG VARCHAR", "ERROR", "ERROR", "ERROR", "CLOB", "DATE", "TIME", "TIMESTAMP", "ERROR" },
VARCHAR { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "VARCHAR", "VARCHAR","LONG VARCHAR", "ERROR", "ERROR", "ERROR", "CLOB", "DATE", "TIME", "TIMESTAMP", "ERROR" },
LONGVARCHAR { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "LONG VARCHAR", "LONG VARCHAR", "LONG VARCHAR", "ERROR", "ERROR", "ERROR", "CLOB", "ERROR", "ERROR", "ERROR", "ERROR" },
CHAR FOR BIT { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "BIT", "BIT VARYING", "LONG BIT VARYING", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
VARCH. BIT { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "BIT VARYING", "BIT VARYING", "LONG BIT VARYING", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
LONGVAR. BIT { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "LONG BIT VARYING", "LONG BIT VARYING", "LONG BIT VARYING", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR" },
CLOB { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "CLOB", "CLOB", "CLOB", "ERROR", "ERROR", "ERROR", "CLOB", "ERROR", "ERROR", "ERROR", "ERROR" },
DATE { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "DATE", "DATE", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "DATE", "ERROR", "ERROR", "ERROR" },
TIME { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIME", "TIME", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIME", "ERROR", "ERROR" },
TIMESTAMP { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIMESTAMP", "TIMESTAMP", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "TIMESTAMP", "ERROR" },
BLOB { "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "ERROR", "BLOB" }
| Methods inherited from class org.apache.derby.impl.sql.compile.ValueNode |
bindExpression, categorize, changeToCNF, checkIsBoolean, checkReliability, checkReliability, checkTopPredicatesForEqualsConditions, constantExpression, copyFields, eliminateNots, genEqualsFalseTree, generate, generateFilter, genIsNullTree, genSQLJavaSQLTree, getClause, getClone, getColumnName, getConstantValueAsObject, getDataValueFactory, getOrderableVariantType, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isCloneable, isConstantExpression, isParameterNode, isRelationalOperator, optimizableEqualityNode, preprocess, putAndsOnTop, remapColumnReferencesToExpressions, selectivity, setClause, setDescriptor, setTransformed, setType, updatableByCursor, verifyChangeToCNF, verifyEliminateNots, verifyPutAndsOnTop |
| Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode |
accept, bind, convertDefaultNode, debugFlush, debugPrint, executeSchemaName, executeStatementName, formatNodeString, foundString, generate, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContextManager, getCursorInfo, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getNodeFactory, getNodeType, getNullNode, getParameterTypes, getRowEstimate, getSchemaDescriptor, getSchemaDescriptor, getSPSName, getStatementType, getTableDescriptor, getTypeCompiler, init, init, init, init, init, init, init, init, init, init, init, init, isAtomic, isInstanceOf, isSessionSchema, isSessionSchema, makeConstantAction, makeResultDescription, makeTableName, needsSavepoint, nodeHeader, optimize, parseQueryText, printLabel, printSubNodes, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setContextManager, setEndOffset, setNodeType, setRefActionInfo, treePrint, treePrint, verifyClassExist |
functionName
java.lang.String functionName
argumentsList
ValueNodeList argumentsList
firstNonParameterNode
ValueNode firstNonParameterNode
CoalesceFunctionNode
public CoalesceFunctionNode()
init
public void init(java.lang.Object functionName,
java.lang.Object argumentsList)
- Initializer for a CalesceFunctionNode
- Overrides:
init in class QueryTreeNode
bindExpression
public ValueNode bindExpression(FromList fromList,
SubqueryList subqueryList,
java.util.Vector aggregateVector)
throws org.apache.derby.iapi.error.StandardException
- Binding this expression means setting the result DataTypeServices.
In this case, the result type is based on the rules in the table listed earlier.
- Overrides:
bindExpression in class ValueNode
generateExpression
public void generateExpression(ExpressionClassBuilder acb,
org.apache.derby.iapi.services.compiler.MethodBuilder mb)
throws org.apache.derby.iapi.error.StandardException
- Do code generation for coalese/value
- Overrides:
generateExpression in class ValueNode
toString
public java.lang.String toString()
- Description copied from class:
ValueNode
- Convert this object to a String. See comments in QueryTreeNode.java
for how this should be done for tree printing.
- Overrides:
toString in class ValueNode
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