如何检查mysql服务器中是否存在数据库？ [英] How to check if database exists in mysql server?

问题描述

大家好，



我正在使用带有MySQL数据库的WPF应用程序。我确实创建了backup.sql文件。然后，在创建.exe文件之后，如何检查db是否存在然后跳过下面的代码？



请帮帮我...



我尝试了什么：



我用过这段代码，

Hello everyone,

I am using WPF apps with MySQL database. I did create backup.sql file. Then, after create .exe file, how can I check if db exist then skip below code?

Please help me...

What I have tried:

I did used this code,

private void Application_Startup(object sender, StartupEventArgs e)  
        {  
            RestoreBehavior();  
        }  

在这里，我如何检查mydb是否存在然后跳过代码？

Here,How can I check here if mydb exist then skip the code?

private void RestoreBehavior()  
        {  
            string constring = "server=localhost;user=root;pwd=123456;";  
            string file = @"C:\Program Files (x86)\xxxx\xxxx\backup.sql";  
            using (MySqlConnection conn = new MySqlConnection(constring))  
            {  
                using (MySqlCommand cmd = new MySqlCommand())  
                {  
                    using (MySqlBackup mb = new MySqlBackup(cmd))  
                    {  
                        cmd.Connection = conn;  
                        conn.Open();  
                        mb.ImportInfo.TargetDatabase = "mydb";/*Here,How can I check here if mydb exist then skip the code?*/
                        mb.ImportInfo.DatabaseDefaultCharSet = "utf8";  
                        mb.ImportFromFile(file);  
                    }  
                }  
            }  
        }  

推荐答案

尝试：

Try:

use information_schema;
SELECT COUNT(*) FROM schemata WHERE SCHEMA_NAME="<db name here>";

public bool DBExists(string conn, string dbName)
{
	bool functionReturnValue = false;

	using (MySqlConnection dbconn = new MySqlConnection(conn)) {
		using (MySqlCommand cmd = new MySqlCommand("SELECT COUNT(*) FROM information_schema.schemata WHERE SCHEMA_NAME=@dbName", conn)) {
			functionReturnValue = false;
cmd.Parameters.AddWithValue("@dbName", dbName);
			dbconn.Open();
			if (cmd.ExecuteNonQuery() != 0) {
				functionReturnValue = true;
			}
			dbconn.Close();
		}
	}
	return functionReturnValue;
}

这篇关于如何检查mysql服务器中是否存在数据库？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！