The purpose is to modify the integer field which captures temperature in decimal.
A good way is to execute a hook_update_N() API in custom module which allows incremental updates when installing, or visiting update.php
WARNING: Does not work. Its better to recreate field after copying data to another temp field.
[ http://drupal.stackexchange.com/questions/103157/modifying-integer-field-to-decimal-gives-error-when-editing-field-information ]
<?php
/**
* Modify the integer field of nursing notes temperature field
* to decimal field with precision and scale
*/
function ji_custom_update_7001() {
// Manual database changes.
db_query("UPDATE {field_config} SET type = 'number_decimal'
WHERE field_name = 'field_nursing_note_max_temp'");
$new_field = array(
'type' => 'numeric',
'precision' => 10,
'scale' => 2,
'not null' => FALSE,
);
// for changing field definition
db_change_field('field_data_field_nursing_note_max_temp', 'field_nursing_note_max_temp_value'
, 'field_nursing_note_max_temp_value', $new_field);
db_change_field('field_revision_field_nursing_note_max_temp', 'field_nursing_note_max_temp_value'
, 'field_nursing_note_max_temp_value', $new_field);
// clear the cache about fields information
field_cache_clear(TRUE);
}
?>