- Home
- Products
- Integration
- Tutorial
- Barcode FAQ
- Purchase
- Company
c# barcode reader sample EXPLORING THE RESULTSET INTERFACE in Font
CHAPTER 5 EXPLORING THE RESULTSET INTERFACE Generate PDF-417 2d Barcode In None Using Barcode creator for Font Control to generate, create PDF 417 image in Font applications. www.OnBarcode.comPDF 417 Drawer In None Using Barcode creation for Font Control to generate, create PDF417 image in Font applications. www.OnBarcode.comSetting Up the Oracle Database
Creating Barcode In None Using Barcode creation for Font Control to generate, create Barcode image in Font applications. www.OnBarcode.comDraw Code128 In None Using Barcode maker for Font Control to generate, create Code 128 image in Font applications. www.OnBarcode.comThe following code shows how to set up the Oracle database: SQL> create table employees ( 2 id varchar(10) not null primary key, 3 name varchar(20) not null, 4 age int 5 ); Table created. SQL> desc employees; Name Null ---------------- -------ID NOT NULL NAME NOT NULL AGE SQL> insert into SQL> insert into SQL> insert into SQL> insert into SQL> insert into SQL> commit; Commit complete. Code-39 Drawer In None Using Barcode drawer for Font Control to generate, create Code 39 Full ASCII image in Font applications. www.OnBarcode.comMake Barcode In None Using Barcode creation for Font Control to generate, create Barcode image in Font applications. www.OnBarcode.comType -----------VARCHAR2(10) VARCHAR2(20) NUMBER(38) name, name, name, name, name) age) values('11', 'Alex Smith', 25); age) values('22', 'Don Knuth', 65); age) values('33', 'Mary Kent', 35); age) values('44', 'Monica Seles', 30); values('99', 'Alex Edison'); EAN-13 Supplement 5 Drawer In None Using Barcode generation for Font Control to generate, create EAN-13 image in Font applications. www.OnBarcode.comPrint Uniform Symbology Specification Code 93 In None Using Barcode generator for Font Control to generate, create USD-3 image in Font applications. www.OnBarcode.comemployees(id, employees(id, employees(id, employees(id, employees(id, Making PDF 417 In Java Using Barcode encoder for BIRT Control to generate, create PDF-417 2d barcode image in Eclipse BIRT applications. www.OnBarcode.comPDF 417 Scanner In C# Using Barcode recognizer for .NET framework Control to read, scan read, scan image in .NET framework applications. www.OnBarcode.comSQL> select id, name, age from employees; ID ---------11 22 33 44 99 NAME AGE -------------------- ---------Alex Smith 25 Don Knuth 65 Mary Kent 35 Monica Seles 30 Alex Edison PDF 417 Generation In Java Using Barcode generation for Java Control to generate, create PDF 417 image in Java applications. www.OnBarcode.comScan Barcode In Java Using Barcode scanner for Java Control to read, scan read, scan image in Java applications. www.OnBarcode.comSetting Up the MySQL Database
Print QR Code In None Using Barcode printer for Word Control to generate, create QR Code image in Word applications. www.OnBarcode.comBarcode Decoder In Java Using Barcode Control SDK for BIRT Control to generate, create, read, scan barcode image in BIRT reports applications. www.OnBarcode.comThe following code shows how to set up the MySQL database: create table employees ( id varchar(10) not null primary key, name varchar(20) not null, age int ); insert insert insert insert insert mysql> into employees(id, name, into employees(id, name, into employees(id, name, into employees(id, name, into employees(id, name) select * from employees; age) values('11', 'Alex Smith', 25); age) values('22', 'Don Knuth', 65); age) values('33', 'Mary Kent', 35); age) values('44', 'Monica Seles', 30); values('99', 'Alex Edison'); Making Code 128A In Visual C# Using Barcode creation for VS .NET Control to generate, create Code 128 Code Set A image in .NET applications. www.OnBarcode.comScanning Barcode In .NET Framework Using Barcode Control SDK for ASP.NET Control to generate, create, read, scan barcode image in ASP.NET applications. www.OnBarcode.comCHAPTER 5 EXPLORING THE RESULTSET INTERFACE
Create QR Code In Java Using Barcode drawer for Android Control to generate, create QR Code ISO/IEC18004 image in Android applications. www.OnBarcode.comGS1 - 12 Generator In Objective-C Using Barcode drawer for iPhone Control to generate, create GTIN - 12 image in iPhone applications. www.OnBarcode.com+----+--------------+------+ | id | name | age | +----+--------------+------+ | 11 | Alex Smith | 25 | | 22 | Don Knuth | 65 | | 33 | Mary Kent | 35 | | 44 | Monica Seles | 30 | | 99 | Alex Edison | NULL | +----+--------------+------+ Five Rows in a Set (0.00 Sec) ANSI/AIM Code 128 Creation In None Using Barcode drawer for Online Control to generate, create Code 128 Code Set A image in Online applications. www.OnBarcode.comMatrix 2D Barcode Encoder In VB.NET Using Barcode printer for Visual Studio .NET Control to generate, create Matrix Barcode image in Visual Studio .NET applications. www.OnBarcode.comSolution
I will now provide a simple Java class to demonstrate how to use ResultSet by querying the employees table and retrieving employee information from a database. Note that the age column can accept null values as well; because of this, after getting the value of age from a ResultSet, you check (by invoking ResultSet.wasNull()) to see if it is a null value. import java.sql.*; import jcb.db.VeryBasicConnectionManager; import jcb.util.DatabaseUtil; public class DemoResultSet { public static void main(String[] args) { Connection conn = null; Statement stmt = null; ResultSet rs = null; try { System.out.println("--DemoResultSet begin--"); String dbVendor = args[0]; // { "mysql", "oracle" } conn = VeryBasicConnectionManager.getConnection(dbVendor); System.out.println("conn="+conn); System.out.println("---------------"); // prepare query String query = "select id, name, age from employees"; // create a statement stmt = conn.createStatement(); // execute query and return result as a ResultSet rs = stmt.executeQuery(query); // extract data from the ResultSet while (rs.next()) { String id = rs.getString(1); System.out.println("id="+id); String name = rs.getString(2); System.out.println("name="+name); // age might be null (according to schema) int age = rs.getInt(3); if (rs.wasNull()) { System.out.println("age=null"); } CHAPTER 5 EXPLORING THE RESULTSET INTERFACE
else { System.out.println("age="+age); } System.out.println("---------------"); } System.out.println("--DemoResultSet end--"); } catch(Exception e){ e.printStackTrace(); System.exit(1); } finally { // release database resources DatabaseUtil.close(rs); DatabaseUtil.close(stmt); DatabaseUtil.close(conn); } } } The important methods and concepts of this solution are as follows: The getConnection() method gets a database connection for the sample Oracle database. createStatement() creates a Statement object for sending SQL statements to the database. executeQuery() is used for Statement objects that return a ResultSet, which is basically a SELECT statement. next() moves the cursor down one row from its current position. The first next() sets the cursor on the first row; the next() method enables you to iterate through all the records retrieved. getString(int columnIndex) retrieves the value of the designated column in the current row of this ResultSet object as a String in the Java programming language. You use getString(1) and getString(2) to get the id and name, respectively. (In the query, id is defined in the first column, and name is defined in the second column.) Note that when using column index, the first column is 1, the second is 2, and so on. getInt(int columnIndex) retrieves the value of the designated column in the current row of this ResultSet object as an int in the Java programming language. You use getInt(3) to get the age of an employee (note that age is defined in the third column of the query). wasNull() reports whether the last column read had a value of SQL NULL. The ResultSet object s getXXX() methods (such as getString() and getInt()) retrieve column data. JDBC defines types to match the SQL data types, and there is a getXXX() method for each. You can use the getXXX() method in two ways with the same semantics. (You can retrieve the value of the designated column in the current row of this ResultSet object as an XXX type.) getXXX(int columnIndex) is the preferred way of getting data since there is no need to get the column s metadata information. getXXX(String columnName) might be a little bit slow because of getting the column s metadata information.
|
|