What do indexes, primary indexes, keywords, primary keywords and primary keys in ACCess mean? What's the difference between a primary key and a primary key?

1, the index can speed up the query of the table. Usually, we set one or several fields that are often used for queries as indexes, but not too many, and it is better to have three fields;

2. It is said that the index is built on one table, while the main index is built on multiple tables. For example, view A consists of multiple tables, and the view contains indexes from multiple tables. Then setting an index in view A is called a primary index.

3. Primary key (keyword) is a field that can uniquely distinguish each piece of data in the table. Primary key is mainly used to associate other tables; Although a table may have multiple fields to distinguish each piece of data, we usually choose the most interesting field that is most easily associated with other tables as the primary key.

4. The primary keyword is like the statement in 2: the primary keyword is based on one table and the primary keyword is based on multiple tables. For example, view A consists of multiple tables, and the view contains keywords from multiple tables. Then set an index in view a, called the primary keyword.