Trigger is a method provided by SQL server to programmers and data analysts to ensure data integrity. It is a special method related to table events. The execution of a stored procedure is not called by a program or started manually, but is triggered by events. (Recommended learning: phpstorm)
For example, when a table is operated (insert, delete, update), its execution will be activated. Triggers are often used to enforce data integrity constraints and business rules. Triggers can be found in the DBA_TRIGGERS and USER_TRIGGERS data dictionaries.
SQL3 trigger is a statement that can be automatically executed by the system to modify the database.
Triggers can query other tables and can contain complex SQL statements. They are primarily used to enforce compliance with complex business rules or requirements. For example: You can control whether new orders are allowed to be inserted based on the customer's current account status.
Triggers can also be used to enforce referential integrity so that when rows are added, updated, or deleted in multiple tables, the relationships defined between those tables are preserved. However, the best way to enforce referential integrity is to define primary key and foreign key constraints in the related tables. If you use a database diagram, you can create relationships between tables to automatically create foreign key constraints.
The only difference between triggers and stored procedures is that triggers cannot execute EXECUTE statement calls, but automatically trigger execution when the user executes a Transact-SQL statement.
In addition, the flip-flop is the basic unit circuit of the logic circuit. It has a memory function and can be used for binary data storage, memory information, etc.
BIT (Binary digit), a computer term, is a unit of information and is a transliteration of the English BIT. It is also a bit in a binary number, a measurement unit of information, and the smallest unit of information.
Information necessary to reduce the number of alternative stimuli by half in situations where a different choice is required. That is, the information amount (number of bits) of the signal is equal to the logarithm of the signal stimulus amount with base 2. L. Hartley believed in 1928 that logarithmic units are most appropriate to measure the amount of information.
In the binary number system, each 0 or 1 is a bit, and a bit is the smallest unit of data storage. Among them, 8bit is called a byte. The number of CPU bits in a computer refers to the maximum number of bits that the CPU can process at one time. For example, the CPU of a 32-bit computer can handle up to 32 bits of data at a time.
Bit is the abbreviation of Binary digit, a term proposed by mathematician John Wilder Tukey (probably proposed in 1946, but some data say it was proposed in 1943).
The first time this term was officially used was on page 1 of Shannon's famous "Information Theory", that is, "A Mathematical Theory of Communication" (A Mathematical Theory of Communication).
The above is the detailed content of How many bits can a flip-flop store?. For more information, please follow other related articles on the PHP Chinese website!