First Level
The logical structure of the data is known as the schema definition. In general, if a user application operates on a subset of the attributes of a relation, it should not be affected later when new attributes are added to the same relation. Logical data independence indicates that the conceptual schema can be changed without affecting the existing schemas.
Read more about this topic: Data Independence
Famous quotes containing the word level:
“I love thee to the level of everyday’s
Most quiet need, by sun and candle-light.
I love thee freely, as men strive for Right;
I love thee purely, as they turn from Praise.
I love thee with the passion put to use
In my old griefs, and with my childhood’s faith.”
—Elizabeth Barrett Browning (1806–1861)
“When science, art, literature, and philosophy are simply the manifestation of personality, they are on a level where glorious and dazzling achievements are possible, which can make a man’s name live for thousands of years. But above this level, far above, separated by an abyss, is the level where the highest things are achieved. These things are essentially anonymous.”
—Simone Weil (1909–1943)