create table command text mysql user defined c#.net

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I'm having problem regarding this code. I try to create table based on database that user defined in c#.net framework.

SchemaName schemaForm = new SchemaName();
            frmMetCon form2 = new frmMetCon();

            if (schemaForm.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
               
              string connStr = "datasource=localhost;port=3306;username=root;password=root;";
              MySqlConnection conn = new MySqlConnection(connStr);
                try
                 {
                   MySqlCommand command = conn.CreateCommand();
                   conn.Open();
                   command.CommandText = "DROP DATABASE IF EXISTS " + schemaForm.getData();
                   command.ExecuteNonQuery();
                   command.CommandText = "CREATE DATABASE " + schemaForm.getData();
                   command.CommandText = "CREATE TABLE Metabolites(MetaboliteID VARCHAR(10) NOT NULL, Metabolite_Name VARCHAR(45) NULL, ReactionTime INT NULL, PRIMARY KEY (MetaboliteID)";
                   command.ExecuteNonQuery();
                   this.Hide();
                   form2.Show();   
                 }
                 catch (Exception ex)
                 {
                   MessageBox.Show(ex.Message); 
                 }
                 conn.Close();
           
             }

The error showing that no database selected. if I create like this

command.CommandText = "CREATE TABLE" +schemaForm.getData()+ ".Metabolites(MetaboliteID VARCHAR(10) NOT NULL, Metabolite_Name VARCHAR(45) NULL, ReactionTime INT NULL, PRIMARY KEY (MetaboliteID)";

I will get error on the command. Please help

Posted 12-Oct-13 7:18am

arave0521

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Nissim Salomon · Answer 1 · 2013-10-12T07:23:00

Solution 1

I think you have a problem with your connection string
check the following MySQL connection strings

Posted 12-Oct-13 7:23am

Nissim Salomon

Comments

arave0521 12-Oct-13 13:28pm

There is nothing wrong with the connection. It works fine. The proble I'm facing is the command of creating table based on user defined the database name
command.CommandText = "CREATE TABLE" +schemaForm.getData()+ ".Metabolites(MetaboliteID VARCHAR(10) NOT NULL, Metabolite_Name VARCHAR(45) NULL, ReactionTime INT NULL, PRIMARY KEY (MetaboliteID)";

Ehsan Skardu · Answer 2 · 2013-10-12T07:36:00

Solution 2

Before you execute the Create table command you must execute the create database command, Like

try
                {
                  MySqlCommand command = conn.CreateCommand();
                  conn.Open();
                  command.CommandText = "DROP DATABASE IF EXISTS " + schemaForm.getData();
                  command.ExecuteNonQuery();
                  command.CommandText = "CREATE DATABASE " + schemaForm.getData();
                    command.ExecuteNonQuery();
                  command.CommandText = "CREATE TABLE Metabolites(MetaboliteID VARCHAR(10) NOT NULL, Metabolite_Name VARCHAR(45) NULL, ReactionTime INT NULL, PRIMARY KEY (MetaboliteID)";
                  command.ExecuteNonQuery();
                  this.Hide();
                  form2.Show();
                }

Posted 12-Oct-13 7:36am

Ehsan Skardu

Comments

arave0521 12-Oct-13 13:40pm

I tried but still got error. The error said that no database selected. if I create

try
{
MySqlCommand command = conn.CreateCommand();
conn.Open();
command.CommandText = "DROP DATABASE IF EXISTS " + schemaForm.getData();
command.ExecuteNonQuery();
command.CommandText = "CREATE DATABASE " + schemaForm.getData();
command.ExecuteNonQuery();
command.Parameters.AddWithValue("@schema",database);
command.CommandText = "CREATE TABLE @schema.Metabolites(MetaboliteID VARCHAR(10) NOT NULL, Metabolite_Name VARCHAR(45) NULL, ReactionTime INT NULL, PRIMARY KEY (MetaboliteID)";
command.ExecuteNonQuery();
this.Hide();
form2.Show();
}

there is still an error

[no name] 12-Oct-13 13:50pm

Oh yes now you show open connection with the new Database you create now and execute the create table query with the new command.

arave0521 12-Oct-13 13:51pm

I don't get it. do you mind showing example?

[no name] 12-Oct-13 14:08pm

try
{
MySqlCommand command = conn.CreateCommand();
conn.Open();
command.CommandText = "DROP DATABASE IF EXISTS " + schemaForm.getData();
command.ExecuteNonQuery();
command.CommandText = "CREATE DATABASE " + schemaForm.getData();
command.ExecuteNonQuery();
conn.close();
command.ExecuteNonQuery();
con.close();
con.connsectionstring=Connectionstring;// this will contain the same server information but database information is the new one,
comand=new conn.CreateCommand()
command.CommandText = "CREATE TABLE Metabolites(MetaboliteID VARCHAR(10) NOT NULL, Metabolite_Name VARCHAR(45) NULL, ReactionTime INT NULL, PRIMARY KEY (MetaboliteID)";
command.ExecuteNonQuery();
this.Hide();
form2.Show();
}

arave0521 12-Oct-13 14:27pm

there is an error on con.connsectionstring=Connectionstring;// this will contain the same server information but database information is the new one,

arave0521 13-Oct-13 8:36am

private void btnNew_Click(object sender, EventArgs e)
{
SchemaName schemaForm = new SchemaName();
frmMetCon form2 = new frmMetCon();

if (schemaForm.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{

string connStr = "datasource=localhost;port=3306;username=root;password=root;";
string database = schemaForm.getData();
MySqlConnection conn = new MySqlConnection(connStr);
try
{
MySqlCommand command = conn.CreateCommand();
conn.Open();
command.CommandText = "DROP DATABASE IF EXISTS " + database;
command.ExecuteNonQuery();
command.CommandText = "CREATE DATABASE " + database;
command.ExecuteNonQuery();
conn.Close();
command.ExecuteNonQuery();
conn.Close();
conn.ConnectionString = connStr;
MySqlCommand comm = conn.CreateCommand();
conn.Open();
comm.CommandText = "CREATE TABLE Metabolites(MetaboliteID VARCHAR(10) NOT NULL, Metabolite_Name VARCHAR(45) NULL, ReactionTime INT NULL, PRIMARY KEY (MetaboliteID)";
comm.ExecuteNonQuery();
this.Hide();
form2.Show();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
conn.Close();

}
}
}

Here is the code I try modified based on you given example. the problem i'm facing now is the conn is not open. i insert open connection but still the same error appear. Any advise?

Member 9472584 matlamis · Answer 3 · 2014-07-26T03:06:00

SchemaName schemaForm = new SchemaName();
            frmMetCon form2 = new frmMetCon();
 
            if (schemaForm.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
               
              string connStr = "datasource=localhost;port=3306;username=root;password=root;";
              MySqlConnection conn = new MySqlConnection(connStr);
                try
                 {
                   MySqlCommand command = conn.CreateCommand();
                   conn.Open();
                   command.CommandText = "DROP DATABASE IF EXISTS " + schemaForm.getData();
                   command.ExecuteNonQuery();
                   command.CommandText = "CREATE DATABASE " + schemaForm.getData();
                   command.ExecuteNonQuery();
                   command.CommandText = "USE " + schemaForm.getData();
                   command.ExecuteNonQuery();
                   command.CommandText = "CREATE TABLE Metabolites(MetaboliteID VARCHAR(10) NOT NULL, Metabolite_Name VARCHAR(45) NULL, ReactionTime INT NULL, PRIMARY KEY (MetaboliteID)";
                   command.ExecuteNonQuery();
                   this.Hide();
                   form2.Show();   
                 }
                 catch (Exception ex)
                 {
                   MessageBox.Show(ex.Message); 
                 }
                 conn.Close();
           
             }