Description of Database Table

This section introduces you how to get the detailed information about the database table.

Description of Database Table

Description of Database Table

     

This section introduces you how to get the detailed information about the database table. As we all know that, table has some specific information like: field, type, null etc.  But how to get all those information by the database. By using a simple query we can get all information about the table like the number of columns and rows in it, its type, whether the field is null or not, whether the column is unique or primary and much more.

Description of program:

While making this program firstly we should establish the connection with MySQL database through the JDBC driver. When the connection has been established, pass the table name in the database query and use some java methods to get the detail description of table. When the program will gets execute then it will show field name,  type and null of the database table. If any field have null value then shows "YES" and if not null then shows "NO". If any problem is created at the time of query, it will show "SQL statement is not executed!".

Description of code:

DESCRIBE table_name;
This code is used to know the brief description of a database table. It takes the name of that table of which we want to see the description.

getColumns(String cat, String sche, String tab, String col_pat)::
This method returns ResultSet object and provides descriptions of table. It takes four string type arguments as given below:
  String cat: This is a table catalog. It may be null value.
  String sche: It shows schema of table. It may be null value.
  String tab: This is a table name. It must require for getting the information.
  String col_pat: It shows column name pattern.

COLUMN_NAME:  Shows column name
TYPE_NAME: data types of column like: integer, varchar, char etc.
COLUMN_SIZE: Column size
NULLABLE: column can be null.

Here is the code of program:

import java.io.*;
import java.sql.*;

public class DiscriptionTable{
  public static void main(String[] args) {
  System.out.println("See Description of Table Example!");
  Connection con = null;
  try{
  Class.forName("com.mysql.jdbc.Driver");
  con = DriverManager.getConnection
(
"jdbc:mysql://localhost:3306/jdbctutorial","root","root");
  try{
  Statement st = con.createStatement();
  BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
  System.out.println("Enter table name:");
  String table = bf.readLine();
  ResultSet rs = st.executeQuery("DESCRIBE "+table);
  ResultSetMetaData md = rs.getMetaData();
  int col = md.getColumnCount();
  for (int i = 1; i <= col; i++){
  String col_name = md.getColumnName(i);
  System.out.print(col_name+"\t");
  }
  System.out.println();
  DatabaseMetaData dbm = con.getMetaData();
  ResultSet rs1 = dbm.getColumns(null,"%",table,"%");
  while (rs1.next()){
  String col_name = rs1.getString("COLUMN_NAME");
  String data_type = rs1.getString("TYPE_NAME");
  int data_size = rs1.getInt("COLUMN_SIZE");
  int nullable = rs1.getInt("NULLABLE");
  System.out.print(col_name+"\t"+data_type+"("+data_size+")"+"\t");
  if(nullable == 1){
  System.out.print("YES\t");
  }
  else{
  System.out.print("NO\t");
  }
  System.out.println();
  }
  }
  catch (SQLException s){
  System.out.println("SQL statement is not executed!");
  }
  }
  catch (Exception e){
  e.printStackTrace();
  }
  }
}

Download this example.

Output of program:

C:\vinod\jdbc\jdbc\jdbc-mysql>javac DiscriptionTable.java

C:\vinod\jdbc\jdbc\jdbc-mysql>java DiscriptionTable
See Description of Table Example!
Enter table name:
vk
Field   Type  Null  Key   Default   Extra
id  int(11)   NO
name  char(1)  YES

Tutorials

  1. Mapping MySQL Data Types in Java
  2. Connecting to a MySQL Database in Java
  3. Creating a Database in MySQL
  4. Creating a Database Table
  5. Creating a MySQL Database Table to store Java Types
  6. Description of Database Table
  7. Deleting a Table from Database
  8. Retrieving Tables from a Database
  9. Inserting values in MySQL database table
  10. Retrieving All Rows from a Database Table
  11. Adding a New Column Name in Database Table
  12. Change Column Name of a Table
  13. Make Unique Column in Database Table
  14. Remove Unique Column in Database Table
  15. Arrange a Column of Database Table
  16. Arrange a Column of Database Table
  17. Sum of Column in a Database Table
  18. Deleting All Rows from a Database Table
  19. Delete a Specific Row from a Database Table
  20. Delete a Column from a Database Table
  21. Join tables in the specific database
  22. Join tables with the NATURAL LEFT JOIN operation
  23. Join tables with the NATURAL RIGHT JOIN operation
  24. Cross Join Tables in a Specific Database
  25. Prepared Statement Set Object
  26. Statement Batch Update
  27. Prepared Statement With Batch Update
  28. Select Records Using Prepared Statement
  29. Update Records using Prepared Statement
  30. Inserting Records using the Prepared Statement
  31. Count Records using the Prepared Statement
  32. Deleting Records using the Prepared Statement
  33. Using the Prepared Statement Twice
  34. Set Data Types by using Prepared Statement
  35. Set byte, short and long data types by using the Prepared Statement
  36. Prepared Statement Set Big Decimal
  37. Set Date by using the Prepared Statement
  38. Set Time by using the Prepared Statement
  39. Set Timestamp by using the Prepared Statement
  40. Copy Table in a MySQL Database