Obtain jagged rows

Jagged rows occur as a result of a query that uses the following syntax to request all the rows in a supertable and all its subtables:

SELECT correlation_variable 
FROM table_name correlation_variable;

In the preceding query, table_name represents a supertable in an inheritance hierarchy. Suppose you create the following schema in which the table parent has one column, child has two columns, and grandchild has three columns:

CREATE TABLE parent OF TYPE parent_t (num1 INTEGER);
INSERT INTO parent VALUES (10);

CREATE TABLE child OF TYPE child_t (num2 SMALLFLOAT) 
   UNDER parent;
INSERT INTO child VALUES (20, 3.5);

CREATE TABLE grandchild OF TYPE grandchild_t (name TEXT)
   UNDER child;
INSERT INTO grandchild VALUES (30, 7.8, 'gundrun');

The following SELECT statement queries the parent supertable:

SELECT p FROM parent p;

This query returns the following three jagged rows:

p (parent_t)
num1
10

p (child_t)
num1             num2
20               3.5E+00

p (grandchild_t)
num1             num2               name
30               7.8E+00            gundrun

The DataBlade® API indicates that a query returned a jagged row as follows:

• The mi_value() or mi_value_by_name() function returns a value status of MI_ROW_VALUE.
• The contents of the MI_DATUM structure that holds the retrieved column is a pointer to a row structure.

The format of the columns depends on whether the control mode for the query data is text or binary representation, as the following table shows.

Control mode	Contents of elements within row structure
Text representation	Null-terminated strings
Binary representation	Internal formats of column values