In Access, you should use pairs if you want to handle operations with complex conditions or loop str

In access, referential integrity rules do not include (query principle).

Access referential integrity is:

physical integrity;

referential integrity;

User-defined integrity.

Referential integrity is one of the complete constraints of the relational model, which is a type of data integrity, and the others are: entity integrity and user-defined integrity.

Referential integrity rule: If the attribute or attribute group f is a foreign key to the fundamental relation r, which corresponds to the primary key ks of the fundamental relation s (the fundamental relation r and s are not necessarily different relations), then the value on f for each tuple in r must be:

1) Null value, each attribute value of f is null.

2) The primary key value (primary code value) in a tuple in s is rounded.

That is, the attribute value in the referenced relationship must be able to be found in the referenced relationship or take a null value, otherwise it does not conform to the semantics of the database. In actual operations, such as updating, deleting, and inserting data in one table, check whether the data operation on the table is correct by referring to the data in another table that is related to each other, and reject the operation if it is incorrect.

Refer to the integrity rule requirements:

1. It is not allowed to enter a value that does not exist in the field of "multi-terminal" with a primary key of "one terminal";

2. If a record has related records in the relational table, the database engine does not allow the record to be deleted from the "one end" (unless you choose to cascade delete related fields, which will delete both the "one side" and the "multi-end" records, so as to ensure the integrity of the data), because if the first case is allowed, the first situation will occur again.

Answer]: B This question tests the basic knowledge of access data types. The field data types in access are:

Text, Number, Date, Notes, Auto-Numbering, Currency, 0le, Yes, Look-up, Look-up Guide, and Hyperlink Friends. The O1 E object is mainly used to link or embed an object into a table in the Encyptic Access database. The text type can store up to 255 characters; The maximum storage capacity of the note type is 64,000 characters; Date-time data occupies 8 bytes; The autonumbering data type occupies 4 bytes.

Answer]: B This question checks the basic knowledge of the friend faction quarrel of the access data type. The field data types in access are:

Text, Number, Date, Time, Notes, Autonumbering, Currency, Ole, Yes or No, Lookup Guide, and Hyperlink. The OLE object is mainly used to link or embed an object in a table in the access database. The text type can store up to 255 characters; The maximum number of g4000 characters can be stored in the remarks type; Date-time data occupies 8 bytes; The autonumbering data type occupies 4 bytes.

The Book Order Form is another table in this database.

Book Order Form]![Unit price] indicates the unit price of the books in that table.

So D is the total amount of the book in the order form.

Because the title doesn't give this table. Select B to get the answer you are looking for.

11. Nationality is not equal to "China", which is correct. ABC (Query) A NOT (Nationality Like "China").

b not(nationality="China").

c Nationality<> "Chinese".

d Nationality not like "China".

44.The following indicates that nationality is not equal to "Chinese", and that the incorrect one is d.

a Nationality! = "China" b not(nationality="China") c nationality<> "China" d nationality not like "China".

11 c Nationality <> "Chinese".

44 a nationality! = "China".