Constants, Identifiers, Names, and Parameters

Note that names in the name operators that contain special characters do not need to be quoted (unlike names in SQL statements). If a name in an operator is quoted, these quotes are part of the name.

The following list describes the operators for constants, identifiers, names, and parameters.

DBOP_scalar_constant

Represents a scalar constant whose value can use any element of the value union of the DBCOMMANDTREE structure. A scalar value can be of any OLE DB type. This node has no inputs. The result type is the type of the scalar value represented by the node.

DBOP_DEFAULT, DBOP_NULL

SQL's "DEFAULT" and "NULL" value indicators. There are no inputs. The result type can be any type of scalar.

DBOP_bookmark_name

Represents the bookmark column of a table (for example, SELECT T.*, T.bookmark FROM T). It takes one optional input, a DBOP_table_name, to which the bookmark belongs. A string representing the name of the column can optionally be assigned in the pwszValue member of DBCOMMANDTREE.

DBOP_catalog_name, DBOP_column_name

Represent the name of a catalog and column, respectively. These nodes have no inputs. A name may be specified by a pwszValue member that is not a null pointer, by a DBID structure, or by a moniker in the node's value field. For column names, the column may be denoted as an unsigned integer value (for example, SELECT A, B FROM T ORDER BY 2).

DBOP_schema_name

Represents the name of a schema. A name may be specified by a pwszValue member that is not a null pointer, by a DBID structure, or by a moniker in the node's value field. A schema name node has an optional input DBOP_catalog_name node.

DBOP_outall_name

Specifies that all input columns (for example, SQL's "SELECT *") must be output. This node has no inputs contains contains no other DBCOMMANDTREE value. DBOP_outall_name is used as an input to the DBOP_project_list_element node, but not to the set_list_element, sort_list_element, column_list_element or from_list_element nodes.

DBOP_qualifier_name

Specifies all columns in a table (for example, SQL's "table.*"). This node has no inputs. The table name is represented by a pwszValue member that is not a null pointer. DBOP_qualifier_name is used as an input to the DBOP_project_list_element node, but not to the set_list_element, sort_list_element, column_list_element or from_list_element nodes.

DBOP_qualified_column_name

Represents a column name. It takes two inputs: a DBOP_table_name, and a DBOP_column_name, in that order. It contains no other DBCOMMANDTREE value.

DBOP_table_name

Represents a table name, possibly in another catalog or schema. A table name may be specified by a pwszValue member that is not a null pointer, by a DBID structure, or by a moniker in the value field of the node. This node takes an optional input: DBOP_schema_name.

DBOP_nested_table name

Represents a nested table name. A nested table is a table containing at least one chaptered column. The component of the nested name is stored as a pwszValue member that is not a null pointer, by a DBID structure, or by a moniker in the value field of the node. This node takes a DBOP_nested_table_name or a DBOP_table_name input. For example, the nested table "Customers.Orders" with chapter "Detail" is represented as follows:

        DBOP_nested_table_name (pwsz = "Detail")
            |
    DBOP_nested_table_name (pwsz = "Orders" )
        |
DBOP_table_name (pwsz = "Customers")

DBOP_nested_column_name

Specifies a column in a nested table. This node takes one DBOP_nested_table_name and a DBOP_column_name as inputs, in that order.