/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.constraint;
import java.util.HashSet;
import org.h2.engine.DbObject;
import org.h2.engine.SessionLocal;
import org.h2.expression.Expression;
import org.h2.expression.ExpressionVisitor;
import org.h2.index.Index;
import org.h2.message.Trace;
import org.h2.result.Row;
import org.h2.schema.Schema;
import org.h2.schema.SchemaObject;
import org.h2.table.Column;
import org.h2.table.Table;
/**
* The base class for constraint checking.
*/
public abstract class Constraint extends SchemaObject implements Comparable<Constraint> {
public enum Type {
/**
* The constraint type for check constraints.
*/
CHECK,
/**
* The constraint type for primary key constraints.
*/
PRIMARY_KEY,
/**
* The constraint type for unique constraints.
*/
UNIQUE,
/**
* The constraint type for referential constraints.
*/
REFERENTIAL,
/**
* The constraint type for domain constraints.
*/
DOMAIN;
/**
* Get standard SQL type name.
*
* @return standard SQL type name
*/
public String getSqlName() {
if (this == Constraint.Type.PRIMARY_KEY) {
return "PRIMARY KEY";
}
if (this == Constraint.Type.REFERENTIAL) {
return "FOREIGN KEY";
}
return name();
}
}
/**
* The table for which this constraint is defined.
*/
protected Table table;
Constraint(Schema schema, int id, String name, Table table) {
super(schema, id, name, Trace.CONSTRAINT);
this.table = table;
if (table != null) {
this.setTemporary(table.isTemporary());
}
}
/**
* The constraint type name
*
* @return the name
*/
public abstract Type getConstraintType();
/**
* Check if this row fulfils the constraint.
* This method throws an exception if not.
*
* @param session the session
* @param t the table
* @param oldRow the old row
* @param newRow the new row
*/
public abstract void checkRow(SessionLocal session, Table t, Row oldRow, Row newRow);
/**
* Check if this constraint needs the specified index.
*
* @param index the index
* @return true if the index is used
*/
public abstract boolean usesIndex(Index index);
/**
* This index is now the owner of the specified index.
*
* @param index the index
*/
public abstract void setIndexOwner(Index index);
/**
* Get all referenced columns.
*
* @param table the table
* @return the set of referenced columns
*/
public abstract HashSet<Column> getReferencedColumns(Table table);
/**
* Returns the CHECK expression or null.
*
* @return the CHECK expression or null.
*/
public Expression getExpression() {
return null;
}
/**
* Get the SQL statement to create this constraint.
*
* @return the SQL statement
*/
public abstract String getCreateSQLWithoutIndexes();
/**
* Check if this constraint needs to be checked before updating the data.
*
* @return true if it must be checked before updating
*/
public abstract boolean isBefore();
/**
* Check the existing data. This method is called if the constraint is added
* after data has been inserted into the table.
*
* @param session the session
*/
public abstract void checkExistingData(SessionLocal session);
/**
* This method is called after a related table has changed
* (the table was renamed, or columns have been renamed).
*/
public abstract void rebuild();
/**
* Get the index of this constraint in the source table, or null if no index
* is used.
*
* @return the index
*/
public Index getIndex() {
return null;
}
/**
* Returns the referenced unique constraint, or null.
*
* @return the referenced unique constraint, or null
*/
public ConstraintUnique getReferencedConstraint() {
return null;
}
@Override
public int getType() {
return DbObject.CONSTRAINT;
}
public Table getTable() {
return table;
}
public Table getRefTable() {
return table;
}
@Override
public int compareTo(Constraint other) {
if (this == other) {
return 0;
}
return Integer.compare(getConstraintType().ordinal(), other.getConstraintType().ordinal());
}
@Override
public boolean isHidden() {
return table != null && table.isHidden();
}
/**
* Visit all elements in the constraint.
*
* @param visitor the visitor
* @return true if every visited expression returned true, or if there are
* no expressions
*/
public boolean isEverything(@SuppressWarnings("unused") ExpressionVisitor visitor) {
return true;
}
}