Database content:
Java source code: (the Code implements the query of the personnel information with a score of 100, and there are comments in the Code for other functions) Note: When running a program in eclipse, You need to insert a jar package into the project, otherwise, an exception occurs! Import java. SQL .*;
Import java. io. *; class database_manage {public Connection conn = null; public ResultSet rs = null; private String DatabaseDriver = "com. mysql. jdbc. Driver ";
// DataSource data source name DSN
Private String DatabaseConnStr = "jdbc: mysql: // localhost: 3306/lele_manage? UseUnicode = true & characterEncoding = utf8"
+ ", Root, root"; public void setDatabaseDriver (String Driver ){
This. DatabaseDriver = Driver;
} Public String getDatabaseDriver (){
Return (this. DatabaseDriver );
} Public void setDatabaseConnStr (String ConnStr ){
This. DatabaseConnStr = ConnStr;
} Public String getDatabaseConnStr (){
Return (this. DatabaseConnStr );
} Public database_manage () {// constructor connects to the database
Try {
Class. forName (DatabaseDriver );
} Catch (java. lang. ClassNotFoundException e ){
System. err. println ("error loading drive:" + e. getMessage ());
System. out. print ("insert execution error:" + e. getMessage (); // output to the client
}
}
Public ResultSet query (String SQL) {// query a database
Rs = null;
Try {
Conn = DriverManager
. GetConnection (
"Jdbc: mysql: // localhost: 3306/people_manage? UseUnicode = true & characterEncoding = utf8 ",
"Root", "root ");
Statement stmt = conn. createStatement ();
Rs = stmt.exe cuteQuery (SQL );
} Catch (SQLException ex ){
System. err. println ("An error occurred while performing the query:" + ex. getMessage ());
System. out. print ("query execution error:" + ex. getMessage (); // output to the client
}
Return rs;
} Public int update_database (String SQL) {// update or insert a database
Int num = 0;
Try {
Conn = DriverManager
. GetConnection (
"Jdbc: mysql: // localhost: 3306/people_manage? UseUnicode = true & characterEncoding = utf8 ",
"Root", "root ");
Statement stmt = conn. createStatement ();
Num = stmt.exe cuteUpdate (SQL );
} Catch (SQLException ex ){
System. err. println ("An error occurred while executing the insert operation:" + ex. getMessage ());
System. out. print ("insert execution error:" + ex. getMessage (); // output to the client
} CloseDataBase ();
Return num;} public void CloseDataBase () {// close the database
Try {
Conn. close ();
} Catch (Exception end ){
System. err. println ("An error occurred while executing the close Connection object:" + end. getMessage ());
System. out. print ("An error occurred while executing and closing the Connection object:" + end. getMessage (); // output to the client
}
} Class people {
Private String uid;
Private String name;
Private String banji;
Private int score; public people (){
} Public people (String uid, String name, String banji ){
This. uid = uid;
This. name = name;
This. banji = banji;
} Public people (String uid, String name, String banji, int score ){
This. uid = uid;
This. name = name;
This. banji = banji;
This. score = score;
} Public String getUid (){
Return uid;
} Public void setUid (String uid ){
This. uid = uid;
} Public String getName (){
Return name;
} Public void setName (String name ){
This. name = name;
} Public String getBanji (){
Return banji;
} Public void setBanji (String banji ){
This. banji = banji;
} Public int getScore (){
Return score;
} Public void setScore (int score ){
This. score = score;
} Public class manage {private people [] people_array1; // object array public void add_people (String uid, String name) {String SQL = "insert people (uid, name) values ('"+ uid +"', '"+ name
+ "')"; // SQL insert statement
// String sql2 = "insert people (uid, name) values ('uid001', 'Tom ')"; database_manage db_obj = new database_manage ();
Db_obj.update_database (SQL );
} Public void update_people (String uid, String name) {String SQL = "update people set name = '" + name + "'where uid ='" + uid
+ "'";
Database_manage db_obj = new database_manage ();
Db_obj.update_database (SQL);} public void delete_people (String uid) {String SQL = "delete from people where uid = '" + uid + "'"; database_manage db_obj = new database_manage (); db_obj.update_database (SQL);} public people query_people (String uid ){
Database_manage db_obj = new database_manage ();
// String adminid = null;
String uid_new, name, banji;
Uid_new = null;
Name = null;
Banji = null;
String SQL _query = "select * from people where uid = '" + uid + "'"; try {
ResultSet rs = db_obj.query (SQL _query );
If (rs. next ()){
Uid_new = rs. getString ("uid ");
Name = rs. getString ("name ");
Banji = rs. getString ("banji ");
}
} Catch (Exception e ){
E. getMessage ();
}
People new_people = new people (uid_new, name, banji );
Return new_people;
} Public people [] query_people_byscore (int score ){
Database_manage db_obj = new database_manage ();
String uid_new, name, banji;
Uid_new = null;
Name = null;
Banji = null;
Int score_new = 0;
String SQL _query = "select * from people where score =" + score; // SQL query statement
Try {
ResultSet rs = db_obj.query (SQL _query); // return the result set after the query.
Int num = 0;
ResultSet rs_new = rs;
While (rs_new.next () {// Number of students in the statistical result set
Num ++;
}
// System. out. println (num );
Lele_array1 = new people [num];
Int I = 0;
Rs. beforeFirst (); // start of the returned result set
While (rs. next ()){
Uid_new = rs. getString ("uid ");
Name = rs. getString ("name ");
Banji = rs. getString ("banji ");
Score_new = rs. getInt ("score ");
People_array1 [I] = new people (uid_new, name, banji, score_new );
I ++;
}
} Catch (Exception e ){
E. getMessage ();
}
Return people_array1;
}
Public static void main (String args []) {
/*
* People new_people = new people ();
*
* Manage mr = new manage (); // mr. add_people ("000", "James"); insert a student's Information
*
* New_people = mr. query_people ("001"); // query the student information of uid = 001. The System. out object is returned.
* Println ("" + new_people.getName () + "" + new_people.getBanji ());
* Mr. update_people ("004", "John"); updates the information of a student.
*
* New_people = mr. query_people ("004"); // query after update
*
* System. out. println ("" + new_people.getName () + "" + new_people.getBanji (
*));
*/
Manage mr = new manage ();
// Mr. delete_people ("001"); Delete student information with uid = 001
People [] lele_array; // declares an array of objects.
Lele_array = mr. query_people_byscore (100); // returns an array of student classes whose score is one hundred, and then outputs
Int num = 0;
Num = lele_array.length;
For (int I = 0; I <num; I ++ ){
System. out. println (lele_array [I]. getUid () + ""
+ People_array [I]. getName () + ""
+ Lele_array [I]. getBanji () + ""
+ Lele_array [I]. getScore ());
}
}
}
Program running result:
