如何使用java检查mysql中的特定数据库是否已存在 [英] How to check if a particular database in mysql already exists using java

问题描述

大家好我是jdbc的新手，我想知道是否有办法检查mysql中是否已经存在某个特定的数据库。

Hi everyone I am new in jdbc and I wanted to find out if there is a way to check if a particular database already exists in mysql.

假设我想创建一个名为students的数据库，如果学生数据库已经在mysql中创建，eclipse中的错误消息将表明该学生数据库已经存在。但是我想要做的是创建一个布尔方法来检查学生数据库是否已经存在。如果它存在则boolean方法将返回false，否则为true，然后我可以创建学生数据库。
我如何用Java做这些？在jdbc中是否有任何方法可以执行此操作，还是需要从头开始编写代码？
感谢您的帮助。

Let's say I wanted to create a database named students, if the students database is already created in mysql an error message in eclipse would state that this students database already exists. However what I wanted to do is to create a boolean method to check if students database already exists. If it exists then boolean method would return false otherwise its true then I can create students database. How do I do these in Java? Are there any methods in jdbc that does this or do I need to code it from scratch? Thanks for your help.

我遵循了mguymons建议，这就是我的意思出现了

I followed mguymons suggestion and this is what I came up

public boolean checkDBExists(String dbName){

    try{
        Class.forName(JDBCDriver); //Register JDBC Driver

        System.out.println("Creating a connection...");
        conn = DriverManager.getConnection(DBURL, USER, PASS); //Open a connection

        ResultSet resultSet = conn.getMetaData().getCatalogs();

        while (resultSet.next()) {

          String databaseName = resultSet.getString(1);
            if(databaseName.equals(dbName)){
                return true;
            }
        }
        resultSet.close();

    }
    catch(Exception e){
        e.printStackTrace();
    }

    return false;
}

推荐答案

您可以从中获取该信息使用 DatabaseMetaData进行 JDBC连接 #getCatalogs ，以下是获取目录的示例，即数据库名称

You can get that info from a JDBC Connection using DatabaseMetaData#getCatalogs, here is an example of getting the Catalogs, aka Database names

// Connection connection = <your java.sql.Connection>
ResultSet resultSet = connection.getMetaData().getCatalogs();

//iterate each catalog in the ResultSet
while (resultSet.next()) {
  // Get the database name, which is at position 1
  String databaseName = resultSet.getString(1);
}
resultSet.close();

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