How to use JDBC to connect to a MySQL database

1.Right-click the new floder in the new project

2.Create a package named lib.

3.The project directory after it has been created.

5.In the project lib package, select paste to paste and copy the mysql jar package.

7.Right-click the MySQL JAR package and select Build Path - Add to Build Path

8.After the addition is completed, the project is associated with the MySQL JAR package, and the relevant classes and methods can now be used.

9.Create a new class in your project.

10.Enter the following**:

11.**Explanation:

driver is an implementation class that is implemented by a specific database vendor.

Its connect method can get a database connection. The parameters are as shown in the figure above.

After running, the output is as follows, which proves that the database connection is successful!

12.Note: This is to use the driver to connect to the database, while the drivermanager or database connection pool is usually used in development, and this is only used to understand the database connection case.

In general, JDBC may not be able to insert data into MySQL for the following reasons:

1.Database connection error: If the URL, username, or password used to connect to the database is incorrect, then the connection fails and data cannot be inserted. You can check whether the connection string is correct to ensure that the connection information in the database is correct.

2.Database table does not exist: If the table you want to insert data into does not exist, then you cannot insert data either. You can check if the correct table name is used, or you can use SQL commands in the database to create a table.

3.Data type error: If the data type to be inserted does not match the data type defined in the table, then the insert operation will also fail. You can check whether the data type segment is correct, or get the table structure information before inserting the data.

4.Primary key or unique index constraint error: If the data to be inserted contains a primary key or unique index value that already exists, the insert operation will also fail.

You can check that the correct primary key or unique index value is used, or query the data that is already in the table before inserting the data.

5.Database permission issue: If the database user you are using does not have permission to insert data, the insert operation will also fail. You can check if the database user has permission to insert data, or if the tasseler uses a user with permission to insert data for insert operations.

In actual development, data may not be inserted due to other factors, such as misconfigured database connection pools and busy database servers. Therefore, you need to double-check your development and configuration to ensure that you can insert the data correctly.

If the JDBC connection to MySQL cannot insert data, there may be several reasons:

1.The database connection was unsuccessful, resulting in data being unable to be inserted. This issue can be caused by incorrect database connection information, username, or password. You need to check that the connection string, username, and password are correct.

2.The database table structure is incorrect, resulting in data not being inserted. This problem may be caused by a mismatch between the structure of the database table and the statement inserting the data. You need to check whether the table structure and the statements that insert the data are correct.

3.The insertion of data is incorrect, resulting in the inability to insert data. This issue may be caused by an incorrect statement inserting data. Xunhe needs to check whether the statement inserting the data is correct.

These problems can be solved by following the following steps:

1.Check whether the database connection information, username, and password are correct to ensure that the connection is successful.

2.Check whether the table structure of the database is correct and make sure that the table structure matches the statement in which the data is inserted.

3.Check that the statement inserting the data is correct and that the statement is correct.

In addition, you can print logs to view specific error messages to help locate the problem. At the same time, you need to make sure that both the database and the table have been created correctly, and that the user has sufficient permissions to perform the insert operation. Shed talk.

There are several common reasons why JDBC connection to MySQL cannot insert data:

1.The database connection is not correctly configured: To connect JDBC to MySQL, you need to configure the database connection information, including the host name, port number, database name, user name, and password. If the connection information is misconfigured, data may not be inserted.

2.Data table does not exist or fields do not match: If you try to insert data into a data table that does not exist, or if the field that does not match the data table, the insert data will also fail.

3.SQL statement writing errors: If SQL statements inserting data are written incorrectly, such as syntax errors or field names, the data insertion will fail.

These problems can be solved by checking the database connection information, table structure, and SQL statements. In addition, you need to pay attention to the problem of the JDBC driver version. There are compatibility problems with different versions of JDBC drivers, and you need to select the appropriate driver version according to the specific situation.

In addition, if JDBC connects to MySQL, you also need to pay attention to the release of database connections. If the connection is not released correctly, it can cause the connection pool to become full, making it impossible to establish new connections. Therefore, after the database connection is consumed, you need to close the connection in time to release resources.