如何使用 VB.NET 从 MySQL 数据库查询数据
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How do I query data from a MySQL Database using VB.NET
提问by Kraxed
I have a MySQL Database called "business elements", which has 4 columns in it (ID,Username,Password & Level). I want to check if a specific username's (given by Usernametextbox.text) "Level" is Admin, Manager or User. These are the 3 values that I want all of my users to have(They are all in the column Level). My connectionstring is "server=localhost;user id=root;password=;database=business elements"and my table is users
我有一个名为“业务元素”的 MySQL 数据库，其中有 4 列（ID、用户名、密码和级别）。我想检查一个特定的用户名（由 给出Usernametextbox.text）“级别”是管理员、经理还是用户。这些是我希望所有用户都拥有的 3 个值（它们都在列级别中）。我的连接字符串是"server=localhost;user id=root;password=;database=business elements"，我的表是users
Basically I want to check the value of a column with a given user.
基本上我想检查给定用户的列的值。
All of this is in Visual Basic.
所有这些都在 Visual Basic 中。
Someone please Help..
有人请帮助..
回答by xpda
Here's how to get the level for a particular username. It should a good starting point for lots of other functions. I haven't tested it, but it should be pretty close. (Userlevel should match the data type for "level"in the table.)
以下是获取特定用户名的级别的方法。它应该是许多其他功能的良好起点。我还没有测试过，但它应该非常接近。（用户级别应与表中“级别”的数据类型匹配。）
Dim conn as MySqlConnection
Dim cmd As MySqlCommand
conn = New MySqlConnection("server=localhost;user id=root;password=;database=business elements;")
conn.Open()
cmd = New MySqlCommand("SELECT level FROM users WHERE Username=@username LIMIT 1", conn)
cmd.Parameters.AddWithValue("@username", Usernametextbox.Text)
userLevel = cmd.ExecuteScalar()
