mysql addition, deletion and modification

MySQL is an open source relational database management system that is widely used in various types of applications. MySQL can perform operations such as adding, deleting, and modifying data. This article will introduce the operations of adding, deleting, and modifying data in MySQL.

1. MySQL's data adding operation

MySQL is a relational database management system that uses SQL language to operate and insert data into the database through the INSERT INTO statement.

Insert a single piece of data:

INSERT INTO table_name (col1,col2,col3,...) VALUES (value1,value2,value3,...);

where table_name is the table name, col is the column name, and value is the data value. For example:

INSERT INTO employees (name,age,gender) VALUES ('John',25,'male');

Insert multiple pieces of data:

INSERT INTO table_name (col1,col2,col3,...) VALUES (value1,value2,value3,...), (value1,value2,value3,...), ...

For example:

INSERT INTO employees (name,age,gender) VALUES ('John',25,'male'), ('Jane',30,'female');

2. MySQL data modification operation

MySQL update statement is used to modify the table data in.

Modify a single piece of data:

UPDATE table_name SET col1 = value1, col2 = value2,... WHERE column_name = some_value;

For example:

UPDATE employees SET name = 'Tom', age = 35 WHERE employee_id = 1;

Modify multiple pieces of data:

UPDATE table_name SET col1 = value1, col2 = value2,... WHERE some_column = some_value;

For example:

UPDATE employees SET age = 30 WHERE gender = 'female';

3. MySQL Delete data operation

MySQL delete statement is used to delete data from the table.

Delete a single piece of data:

DELETE FROM table_name WHERE some_column = some_value;

For example:

DELETE FROM employees WHERE employee_id = 2;

Delete multiple pieces of data:

DELETE FROM table_name WHERE some_column = some_value;

For example:

DELETE FROM employees WHERE age > 30;

Things to note Yes, deleting data is irreversible, so you need to think carefully before executing it to avoid irreversible consequences.

4. MySQL transaction processing

The transaction processing function of MySQL can ensure the atomicity, consistency, isolation and durability of data operations.

A transaction is a series of operations connected together. These operations require all executions to be successful or all to fail to ensure data integrity.

The syntax of transaction processing is as follows:

START TRANSACTION; MySQL的SQL语句; MySQL的SQL语句; MySQL的SQL语句; COMMIT;

When an error occurs during execution, you can use the ROLLBACK statement to roll back the transaction.

START TRANSACTION; MySQL的SQL语句; MySQL的SQL语句; MySQL的SQL语句; ROLLBACK;

5. Summary of MySQL

MySQL is a powerful and flexible relational database management system that can perform a variety of data operations, including adding, modifying and deleting data. Care needs to be taken when performing these operations and data integrity and consistency must be ensured. In addition, MySQL's transaction processing capabilities ensure the atomicity, consistency, isolation, and durability of operations. These operations are very important for both developers and database administrators because they can ensure the correctness of the data and protect the security of important information.

The above is the detailed content of mysql addition, deletion and modification. For more information, please follow other related articles on the PHP Chinese website!