Class: ActiveRecord::ConnectionAdapters::IBM_DB2_LUW

Inherits:
IBM_DB2
  • Object
show all
Defined in:
lib/connection_adapters/ibm_db_adapter.rb

Instance Method Summary collapse

Instance Method Details

#constraints(table_name, name = nil) ⇒ Object

:nodoc



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# File 'lib/connection_adapters/ibm_db_adapter.rb', line 60

def constraints(table_name, name = nil) #:nodoc
      constraints = []  
      upcase_table_name = table_name.upcase  
      sql = %Q{
        select CST.tabschema, CST.constname, LOWER(CST.tabname) as tabname, CST.type, 
          LOWER(COL.colname) as colname, REF.constname as foreign_constraint_name, 
          LOWER(REF.tabname) as foreign_table_name, REF.refkeyname, 
          LOWER(REF.reftabname) as reftabname, REF.deleterule, 
          REF.fk_colnames as foreign_columns, REF.pk_colnames as referenced_columns 
        from 
          ((select * from SYSCAT.TABCONST where tabname='#{upcase_table_name}') as CST 
        inner join 
          (select colname, constname from SYSCAT.KEYCOLUSE 
          where tabname='#{upcase_table_name}') as COL 
          on (CST.constname=COL.constname)) 
        left outer join SYSCAT.REFERENCES REF 
          on (CST.constname=REF.refkeyname or CST.constname=REF.constname)
        }       
      
  results = IBM_DB::exec(@adapter.connection, sql)
  constraint_name_hash = {}
   
  # Note that column names in constraint objects are downcased in order to
  # be comparable with the column names produced by IBM_DBAdapter.columns  
  while row = IBM_DB::fetch_assoc(results)
      constraint_name = row['constname']
      foreign_constraint_name = row['foreign_constraint_name']
        column_name = row['colname']
        table_name = row['tabname']
        referenced_columns = row['referenced_columns'].downcase.split if row['referenced_columns']
        foreign_columns = row['foreign_columns'].downcase.split if row['foreign_columns']
  
        # Process constraints local to this table
      if !constraint_name_hash.has_key?(constraint_name)
        current_constraint = IBM_DBConstraint.new(row['tabschema'], constraint_name, row['type'], 
          table_name, column_name, row['refkeyname'], row['reftabname'], 
            referenced_columns, row['deleterule'])
        constraints << current_constraint
        constraint_name_hash[constraint_name] = current_constraint
      # This key is a composite
      else
        current_constraint = constraint_name_hash[constraint_name]
          current_constraint.column_names << column_name unless current_constraint.column_names.include?(column_name)
          referenced_columns.each do |column|
            current_constraint.referenced_column_names << column unless current_constraint.referenced_column_names.include?(column)
          end
      end
    
      # Process constraints that reference this table's local constraints
        if foreign_constraint_name
      if !constraint_name_hash.has_key?(foreign_constraint_name)
        current_foreign_constraint = IBM_DBConstraint.new(row['tabschema'], foreign_constraint_name, 
          IBM_DBConstraint::FOREIGN_KEY_TYPE,  row['foreign_table_name'], foreign_columns, 
constraint_name, table_name, column_name, row['deleterule'])
          constraints << current_foreign_constraint
          constraint_name_hash[foreign_constraint_name] = current_foreign_constraint
      # Composite FK 
      else
        current_foreign_constraint = constraint_name_hash[foreign_constraint_name]
            foreign_columns.each do |fc|
current_foreign_constraint.column_names << fc unless current_foreign_constraint.column_names.include?(fc)
            end
            referenced_columns.each do |rc|
current_foreign_constraint.referenced_column_names << rc unless current_foreign_constraint.referenced_column_names.include?(rc) 
        end
          end  
        end      
  end
  constraints
end