Class AsOfClause
- java.lang.Object
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- org.eclipse.persistence.jpa.jpql.parser.AbstractExpression
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- org.eclipse.persistence.jpa.jpql.parser.AsOfClause
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- All Implemented Interfaces:
Expression
public final class AsOfClause extends AbstractExpression
AnAS OFclause is part of a flashback query, which provides ways to view past states of database objects, or to return database objects to a previous state, without using traditional point-in-time recovery.Specify
AS OFto retrieve the single version of the rows returned by the query at a particular change number (SCN) or timestamp. If you specify SCN, then the expression must evaluate to a number. If you specifyTIMESTAMP, then the expression must evaluate to a timestamp value. Oracle Database returns rows as they existed at the specified system change number or time.BNF:asof_clause ::= AS OF { SCN | TIMESTAMP } scalar_expression- Version:
- 2.5
- Author:
- Pascal Filion
- Since:
- 2.5
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Field Summary
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Fields inherited from class org.eclipse.persistence.jpa.jpql.parser.AbstractExpression
COMMA, DOT, DOUBLE_QUOTE, LEFT_CURLY_BRACKET, LEFT_PARENTHESIS, NOT_DEFINED, RIGHT_CURLY_BRACKET, RIGHT_PARENTHESIS, SINGLE_QUOTE, SPACE, UNDERSCORE
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Fields inherited from interface org.eclipse.persistence.jpa.jpql.parser.Expression
ABS, ALL, AND, ANY, AS, AS_OF, ASC, AVG, BETWEEN, BIT_LENGTH, BOTH, CASE, CAST, CHAR_LENGTH, CHARACTER_LENGTH, CLASS, COALESCE, COLUMN, CONCAT, CONNECT_BY, COUNT, CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, DELETE, DELETE_FROM, DESC, DIFFERENT, DISTINCT, DIVISION, ELSE, EMPTY, END, ENTRY, EQUAL, ESCAPE, EXCEPT, EXISTS, EXTRACT, FALSE, FETCH, FIRST, FROM, FUNC, FUNCTION, GREATER_THAN, GREATER_THAN_OR_EQUAL, GROUP_BY, HAVING, IN, INDEX, INNER, INNER_JOIN, INNER_JOIN_FETCH, INTERSECT, IS, IS_EMPTY, IS_NOT_EMPTY, IS_NOT_NULL, IS_NULL, JOIN, JOIN_FETCH, KEY, LAST, LEADING, LEFT, LEFT_JOIN, LEFT_JOIN_FETCH, LEFT_OUTER_JOIN, LEFT_OUTER_JOIN_FETCH, LENGTH, LIKE, LOCATE, LOWER, LOWER_THAN, LOWER_THAN_OR_EQUAL, MAX, MEMBER, MEMBER_OF, MIN, MINUS, MOD, MULTIPLICATION, NAMED_PARAMETER, NEW, NOT, NOT_BETWEEN, NOT_EQUAL, NOT_EXISTS, NOT_IN, NOT_LIKE, NOT_MEMBER, NOT_MEMBER_OF, NULL, NULLIF, NULLS, NULLS_FIRST, NULLS_LAST, OBJECT, OF, ON, OPERATOR, OR, ORDER_BY, ORDER_SIBLINGS_BY, OUTER, PLUS, POSITION, POSITIONAL_PARAMETER, QUOTE, REGEXP, SCN, SELECT, SET, SIZE, SOME, SQL, SQRT, START_WITH, SUBSTRING, SUM, TABLE, THEN, TIMESTAMP, TRAILING, TREAT, TRIM, TRUE, TYPE, UNION, UNKNOWN, UPDATE, UPPER, VALUE, WHEN, WHERE
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Constructor Summary
Constructors Constructor Description AsOfClause(AbstractExpression parent)Creates a newAsOfClause.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description voidaccept(ExpressionVisitor visitor)Visits thisExpressionby the givenvisitor.voidacceptChildren(ExpressionVisitor visitor)Visits the children of thisExpression.protected voidaddChildrenTo(java.util.Collection<Expression> children)Adds the children of thisAbstractExpressionto the given collection.protected voidaddOrderedChildrenTo(java.util.List<Expression> children)Adds the children of thisAbstractExpressionto the given list.JPQLQueryBNFfindQueryBNF(Expression expression)Retrieves theJPQLQueryBNFthat represents the fragment of thisExpressionthat was used when parsing the givenExpression.java.lang.StringgetActualIdentifier()Returns the actual AS OF identifier found in the string representation of the JPQL query, which has the actual case that was used.java.lang.StringgetActualScnIdentifier()Returns the actual SCN identifier found in the string representation of the JPQL query, which has the actual case that was used.java.lang.StringgetActualTimestampIdentifier()Returns the actual TIMESTAMP identifier found in the string representation of the JPQL query, which has the actual case that was used.ExpressiongetExpression()Returns theExpressionrepresenting the timestamp or change number.JPQLQueryBNFgetQueryBNF()Returns the BNF of thisExpression.booleanhasExpression()Determines whether theExpressionrepresenting the timestamp or change number was parsed or not.booleanhasScn()Determines whether the identifier SCN was part of the query.booleanhasSpaceAfterCategory()Determines whether a whitespace was found after either SCN orTIMESTAMP.booleanhasSpaceAfterIdentifier()Determines whether a whitespace was found after AS OF.booleanhasTimestamp()Determines whether the identifier TIMESTAMP was part of the query.protected voidparse(WordParser wordParser, boolean tolerant)Parses the query by starting at the current position, which is part of the givenWordParser.protected voidtoParsedText(java.lang.StringBuilder writer, boolean actual)Generates a string representation of thisExpression, including its children, if it has any.-
Methods inherited from class org.eclipse.persistence.jpa.jpql.parser.AbstractExpression
acceptUnknownVisitor, acceptUnknownVisitor, buildExpressionFromFallingBack, buildNullExpression, buildStringExpression, buildStringExpression, buildUnknownExpression, calculatePosition, children, findFallBackExpressionFactory, getExpressionFactory, getExpressionRegistry, getGrammar, getIdentifierVersion, getJPAVersion, getLength, getOffset, getParent, getQueryBNF, getRoot, getText, handleAggregate, handleCollection, isAncestor, isIdentifier, isNull, isParsingComplete, isTolerant, isUnknown, isVirtual, orderedChildren, parse, parseUsingExpressionFactory, populatePosition, rebuildActualText, rebuildParsedText, setParent, setText, shouldParseWithFactoryFirst, shouldSkipLiteral, toActualText, toParsedText, toString
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Constructor Detail
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AsOfClause
public AsOfClause(AbstractExpression parent)
Creates a newAsOfClause.- Parameters:
parent- The parent of this expression
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Method Detail
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accept
public void accept(ExpressionVisitor visitor)
Visits thisExpressionby the givenvisitor.- Parameters:
visitor- TheExpressionVisitorto visit this object
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acceptChildren
public void acceptChildren(ExpressionVisitor visitor)
Visits the children of thisExpression. This method can be used to optimize traversing the children since a new list is not created every timeExpression.children()is called.This does not traverse the
Expressionsub-hierarchy, use a subclass ofAbstractTraverseChildrenVisitorin order to traverse the entire sub-hierarchy.- Parameters:
visitor- Thevisitorto visit the children of this object.
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addChildrenTo
protected void addChildrenTo(java.util.Collection<Expression> children)
Adds the children of thisAbstractExpressionto the given collection.- Overrides:
addChildrenToin classAbstractExpression- Parameters:
children- The collection used to store the children
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addOrderedChildrenTo
protected void addOrderedChildrenTo(java.util.List<Expression> children)
Adds the children of thisAbstractExpressionto the given list.- Overrides:
addOrderedChildrenToin classAbstractExpression- Parameters:
children- The list used to store the string representation of thisAbstractExpression
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findQueryBNF
public JPQLQueryBNF findQueryBNF(Expression expression)
Retrieves theJPQLQueryBNFthat represents the fragment of thisExpressionthat was used when parsing the givenExpression.- Specified by:
findQueryBNFin interfaceExpression- Overrides:
findQueryBNFin classAbstractExpression- Parameters:
expression- TheExpressionthat is a descendant of this one- Returns:
- The
JPQLQueryBNFthat was used to parse the given expression
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getActualIdentifier
public java.lang.String getActualIdentifier()
Returns the actual AS OF identifier found in the string representation of the JPQL query, which has the actual case that was used.- Returns:
- The AS OF identifier that was actually parsed
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getActualScnIdentifier
public java.lang.String getActualScnIdentifier()
Returns the actual SCN identifier found in the string representation of the JPQL query, which has the actual case that was used.- Returns:
- The SCN identifier that was actually parsed, or an empty string if it was not parsed
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getActualTimestampIdentifier
public java.lang.String getActualTimestampIdentifier()
Returns the actual TIMESTAMP identifier found in the string representation of the JPQL query, which has the actual case that was used.- Returns:
- The TIMESTAMP identifier that was actually parsed, or an empty string if it was not parsed
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getExpression
public Expression getExpression()
Returns theExpressionrepresenting the timestamp or change number.- Returns:
- The
Expressionthat was parsed representing the timestamp or change number
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getQueryBNF
public JPQLQueryBNF getQueryBNF()
Returns the BNF of thisExpression.- Returns:
- The
JPQLQueryBNF, which represents the grammar of thisExpression
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hasExpression
public boolean hasExpression()
Determines whether theExpressionrepresenting the timestamp or change number was parsed or not.- Returns:
trueif the timestamp or change number was parsed;falseotherwise
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hasScn
public boolean hasScn()
Determines whether the identifier SCN was part of the query.- Returns:
trueif the identifier SCN was parsed;falseotherwise
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hasSpaceAfterCategory
public boolean hasSpaceAfterCategory()
Determines whether a whitespace was found after either SCN orTIMESTAMP.- Returns:
trueif there was a whitespace after SCN orTIMESTAMP;falseotherwise
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hasSpaceAfterIdentifier
public boolean hasSpaceAfterIdentifier()
Determines whether a whitespace was found after AS OF.- Returns:
trueif there was a whitespace after AS OF;falseotherwise
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hasTimestamp
public boolean hasTimestamp()
Determines whether the identifier TIMESTAMP was part of the query.- Returns:
trueif the identifier TIMESTAMP was parsed;falseotherwise
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parse
protected void parse(WordParser wordParser, boolean tolerant)
Parses the query by starting at the current position, which is part of the givenWordParser.- Specified by:
parsein classAbstractExpression- Parameters:
wordParser- The text to parse based on the current position of the cursortolerant- Determines whether the parsing system should be tolerant, meaning if it should try to parse invalid or incomplete queries
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toParsedText
protected void toParsedText(java.lang.StringBuilder writer, boolean actual)Generates a string representation of thisExpression, including its children, if it has any.- Specified by:
toParsedTextin classAbstractExpression- Parameters:
writer- The buffer used to append thisExpression's string representationactual- Determines whether the string representation should represent what was parsed, i.e. include any "virtual" whitespace (such as ending whitespace) and the actual case of the JPQL identifiers
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