Resolving the anchor object for an anchored type

The anchor object of an anchored type that does not specify ROW is specified with a name that could represent an SQL variable, an SQL parameter, a global variable, a module variable, a column of a table, or a column of a view.

The way the anchor object is resolved depends on the number of identifiers in the anchor object name and the context of the statement using the ANCHOR clause.
  • If the anchor object name is specified with 1 identifier, the name could represent an SQL variable, an SQL parameter, a module variable, or a global variable.
  • If the anchor object name is specified with 2 identifiers, the name could represent a label-qualified SQL variable, a routine-qualified SQL parameter, a schema-qualified global variable, a module variable, the column of a table, or the column of a view.
  • If the anchor object name is specified with 3 identifiers, the name represents a column of a schema-qualified table, a column of a schema-qualified view, a global variable qualified by the current server name and a schema, or a schema-qualified module variable.
An SQL variable is a candidate for an anchor object name only if the ANCHOR clause is used in an SQL variable declaration within a compound statement. An SQL parameter is a candidate for an anchor object name only if the ANCHOR clause is used in an SQL variable declaration within a compound statement used in an SQL routine body.
Resolving the anchor object name that has 1 identifier is done using the following steps:
  1. If the ANCHOR clause is in an SQL variable declaration of a compound statement, search for a matching SQL variable name starting from the innermost nested compound to the outermost compound.
  2. If the ANCHOR clause is in an SQL variable declaration of a compound statement within a routine body, search for a matching SQL parameter name for the routine.
  3. If the ANCHOR clause is used in defining a module object, then search for a matching module variable name within the module.
  4. If not yet found, then search for a table or view using the first identifier as the schema name and the second identifier as the table or view name.
  5. If not yet found, then search for a global variable with a matching global variable name on the SQL path.
Resolving the anchor object name that has 2 identifiers is done using the following steps:
  1. If the ANCHOR clause is in an SQL variable declaration of a compound statement, search for a matching qualified SQL variable name starting from the innermost nested compound to the outermost compound.
  2. If the ANCHOR clause is in an SQL variable declaration of a compound statement within a routine body, search for a matching SQL parameter name for the routine if the first identifier of the anchor object name matches the name of the routine.
  3. If the ANCHOR clause is used in defining a module object and if the first identifier matches the module name of that module, then search for a module variable name within the module that matches the second identifier.
  4. If not yet found, then search for a table or view column in the current schema using the first identifier as a table or view name and the second identifier as a column name.
  5. If not yet found, then search for a global variable using the first identifier as a schema name and the second identifier as a global variable name.
  6. If not found and a module was not searched in step 3, then search for a module on the SQL path with a name that matches the first identifier. If found, then use the second identifier to search for a matching published module variable name in the module.
  7. If a module is not found using the SQL path in step 6, check for a module public alias that matches the name of the first identifier. If found, then use the second identifier to search for a matching published module variable name in the module identified by the module public alias.
Resolving the anchor object name that has 3 identifiers is done using the following steps:
  1. If the ANCHOR clause is used in defining a module object and if the first 2 identifiers match the schema name and the module name of that module, then search for a module variable with a name that matches the last identifier.
  2. If not found in the previous step or the step is not applicable, then search for a table or view column using the first identifier as a schema name, the second identifier as a table or view name and the third identifier as a column name.
  3. If not found in the previous step and the first identifier is the same as the current server name, then search for a global variable using the second identifier as a schema name, and the third identifier as a global variable name.
  4. If not found and a module was not searched in step 1, then search for a published module variable using the first identifier as a schema name, the second identifier as a module name and, if such a module exists, use the third identifier to search for a matching published module variable name in the module.