Class JoiningSet

java.lang.Object
com.mckoi.database.JoiningSet
All Implemented Interfaces:
Serializable, Cloneable

public final class JoiningSet extends Object implements Serializable, Cloneable
Used in TableSet to describe how we naturally join the tables together. This is used when the TableSet has evaluated the search condition and it is required for any straggling tables to be naturally joined. In SQL, these joining types are specified in the FROM clause.

For example,

   FROM table_a LEFT OUTER JOIN table_b ON ( table_a.id = table_b.id ), ...
 

A ',' should donate an INNER_JOIN in an SQL FROM clause.

Author:
Tobias Downer
See Also:
  • Field Details

  • Constructor Details

    • JoiningSet

      public JoiningSet()
      Constructs the JoiningSet.
  • Method Details

    • prepare

      public void prepare(DatabaseConnection connection)
      Resolves the schema of tables in this joining set. This runs through each table in the joining set and if the schema has not been set for the table then it attempts to resolve it against the given DatabaseConnection object. This would typically be called in the preparation of a statement.
    • addTable

      public void addTable(TableName table_name)
      Adds a new table into the set being joined. The table name should be the unique name that distinguishes this table in the TableSet.
    • addPreviousJoin

      public void addPreviousJoin(int type, Expression on_expression)
      Hack, add a joining type to the previous entry from the end. This is an artifact of how joins are parsed.
    • addJoin

      public void addJoin(int type, Expression on_expression)
      Adds a joining type to the set, and an 'on' expression.
    • addJoin

      public void addJoin(int type)
      Adds a joining type to the set with no 'on' expression.
    • getTableCount

      public int getTableCount()
      Returns the number of tables that are in this set.
    • getFirstTable

      public TableName getFirstTable()
      Returns the first table in the join set.
    • getTable

      public TableName getTable(int n)
      Returns table 'n' in the result set where table 0 is the first table in the join set.
    • getJoinType

      public int getJoinType(int n)
      Returns the type of join after table 'n' in the set. An example of using this;

      
       String table1 = joins.getFirstTable();
       for (int i = 0; i invalid input: '<' joins.getTableCount() - 1; ++i) {
         int type = joins.getJoinType(i);
         String table2 = getTable(i + 1);
         // ... Join table1 and table2 ...
         table1 = table2;
       }
      
       
    • getOnExpression

      public Expression getOnExpression(int n)
      Returns the ON Expression for the type of join after table 'n' in the set.
    • clone

      public Object clone() throws CloneNotSupportedException
      Performs a deep clone on this object.
      Overrides:
      clone in class Object
      Throws:
      CloneNotSupportedException