JDBC没有执行SHOW DATABASES命令 [英] JDBC is not executing SHOW DATABASES command

问题描述

我想获取存储在mysql中的数据库列表，并通过结果集使用命令显示数据库"将其放在java表中.但它不起作用.

DefaultTableModel model=(DefaultTableModel)dbTbl.getModel();
try{
    Class.forName("com.mysql.jdbc.Driver");
    Connection con=DriverManager.getConnection("jdbc:mysql//localhost/:3306","root","password");
    Statement stmt=con.createStatement();
    ResultSet rs=stmt.executeQuery("show databases;");
    while(rs.next())
   {
    String db=rs.getString(1);
    model.addRow(new Object[] {db});
   }
    rs.close();
    stmt.close();
    con.close();
}
catch(Exception e)
{
    JOptionPane.showMessageDialog(null,"nahi chalda");
}

解决方案

这不是在JDBC中获取数据库列表的最佳方法.这是完成的方式-使用MetaData

Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost/:3306","root","password");
DatabaseMetaData meta = con.getMetaData();
ResultSet resultSet = meta.getCatalogs();
while (resultSet.next()) {
   String db = resultSet.getString("TABLE_CAT");
   model.addRow(new Object[] {db});
}
resultSet.close();
con.close();

另请参见:如何获取数据库模式"列表使用Java JDBC的MySql的名称

i want to get a list of databases stored in mysql and put in java table using command "show databases" via a resultset. but its not working.

DefaultTableModel model=(DefaultTableModel)dbTbl.getModel();
try{
    Class.forName("com.mysql.jdbc.Driver");
    Connection con=DriverManager.getConnection("jdbc:mysql//localhost/:3306","root","password");
    Statement stmt=con.createStatement();
    ResultSet rs=stmt.executeQuery("show databases;");
    while(rs.next())
   {
    String db=rs.getString(1);
    model.addRow(new Object[] {db});
   }
    rs.close();
    stmt.close();
    con.close();
}
catch(Exception e)
{
    JOptionPane.showMessageDialog(null,"nahi chalda");
}

解决方案

That's not the best way to get a list of Databases in JDBC. Here's the way it's done - using MetaData

Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost/:3306","root","password");
DatabaseMetaData meta = con.getMetaData();
ResultSet resultSet = meta.getCatalogs();
while (resultSet.next()) {
   String db = resultSet.getString("TABLE_CAT");
   model.addRow(new Object[] {db});
}
resultSet.close();
con.close();

See also: how to get list of Databases "Schema" names of MySql using java JDBC

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