Dynamically insert data in the table using JDBC

Question

I have 1 table in mysql database and another table in oracle database. I am writing an utility to get data from one table and insert into another table.

The following is my design of the utility tool in swing.

Textarea for select query; Another Textarea for insert query; A button called load data.

Now if i click the load data, select query should run and pick up the data. And execute the insert query to insert in to the table.

Note :Since it is an utility tool, the table names are dynamic.

The problem i am facing right now is with the insert query. How can i dynamically find the desc of the table so that i can use setString, setLong or ect during the run time?

Answer 1

ResultSetMetaData can tell you about a ResultSet (and hence a table):

 ResultSet rs = stmt.executeQuery("SELECT a, b, c FROM TABLE2");
 ResultSetMetaData rsmd = rs.getMetaData();
 int numberOfColumns = rsmd.getColumnCount();
 boolean b = rsmd.isSearchable(1);

Answer 2

Here is an example of how a ResultSetMetaData object can tell you about the table you've queried:

import java.sql.*;

public class JDBCQuery {

    public static void main(String args[]) {
        Connection conn = null;
        Statement s = null;
        try {
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            conn = DriverManager.getConnection(
                    "jdbc:odbc:Driver={SQL Server};" + 
                    "Server=.\\SQLEXPRESS;" +
                    "Trusted_Connection=yes;" +
                    "Database=myDb");
            s = conn.createStatement();
            s.executeQuery("SELECT * FROM dbo.SalesSummary WHERE 0 = 1");
            ResultSet rs = s.getResultSet();
            ResultSetMetaData rsmd = rs.getMetaData();
            for (int i = 1; i <= rsmd.getColumnCount(); i++) {
                System.out.println(String.format("-- Column %d --", i));
                System.out.println(String.format("Column name: %s", rsmd.getColumnName(i)));
                System.out.println(String.format("Database-specific type name: %s", rsmd.getColumnTypeName(i)));
                System.out.println(String.format("Column size (DisplaySize): %d", rsmd.getColumnDisplaySize(i)));
                System.out.println(String.format("java.sql.Type of column: %d", rsmd.getColumnType(i)));
                System.out.println();
            }
        } catch( Exception e ) {
            e.printStackTrace();
        } finally {
            try {
                if (s != null) {
                    s.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch( Exception e ) {
                e.printStackTrace();
            }
        }
    }
}

Here is the output:

-- Column 1 --
Column name: Item
Database-specific type name: nvarchar
Column size (DisplaySize): 255
java.sql.Type of column: -9

-- Column 2 --
Column name: FiscalYear
Database-specific type name: int
Column size (DisplaySize): 11
java.sql.Type of column: 4

-- Column 3 --
Column name: Quarter
Database-specific type name: int
Column size (DisplaySize): 11
java.sql.Type of column: 4

-- Column 4 --
Column name: Sales
Database-specific type name: money
Column size (DisplaySize): 21
java.sql.Type of column: 3

A complete list of java.sql.Types is available here .

Answer 3

Here some code I write recently to generate some scripts dynamically. Queries the database metadata to get information about all views with the prefix vw_as. You should be able to use this as a starting point to query the table you want to insert into and get its definition.

DataSource ds = ...;
Connection c = ds.getConnection();
DatabaseMetaData metaData = c.getMetaData();

ResultSet rs = metaData.getTables(null, "dbo", "vw_as%", new String[] { "VIEW" });

while (rs.next()) {
    String tableName = rs.getString("TABLE_NAME"));

    ResultSet rs1 = metaData.getColumns(null, "dbo", tableName, "%");

    while (rs1.next()) {
        String columnName = rs1.getString("COLUMN_NAME"));
    }
  }
}