Description of the illustration previous.gif

The `PREVIOUS`

function can be used only in the `model_clause`

of the `SELECT`

statement and then only in the `ITERATE`

... [ `UNTIL`

`]`

clause of the `model_rules_clause`

. It returns the value of `cell_reference`

at the beginning of each iteration.

The following example repeats the rules, up to 1000 times, until the difference between the values of `cur_val`

at the beginning and at the end of an iteration is less than one:

SELECT dim_col, cur_val, num_of_iterations FROM (SELECT 1 AS dim_col, 10 AS cur_val FROM dual) MODEL DIMENSION BY (dim_col) MEASURES (cur_val, 0 num_of_iterations) IGNORE NAV UNIQUE DIMENSION RULES ITERATE (1000) UNTIL (PREVIOUS(cur_val[1]) - cur_val[1] < 1) ( cur_val[1] = cur_val[1]/2, num_of_iterations[1] = num_of_iterations[1] + 1 ); DIM_COL CUR_VAL NUM_OF_ITERATIONS ---------- ---------- ----------------- 1 .625 4