SQLiteHelper

 1 /**

 2  * 实现对表的创建、更新、变更列名操作

 3  *

 4  *

 5  */

 6 public class SQLiteHelper extends SQLiteOpenHelper {

 7     public static final String DB_NAME = "historyDB";

 8     public static final String TB_NAME = "historyTB";

 9     

10     public SQLiteHelper(Context context)

11     {

12         super(context, DB_NAME, null, 1);

13     }

14     

15     /**

16      * 创建新表

17      */

18     @Override

19     public void onCreate(SQLiteDatabase db) {

20         db.execSQL("CREATE TABLE IF NOT EXISTS " +

21                 TB_NAME + "(" +

22                 //HistoryBean.ID + " integer primary key," +

23                 HistoryBean.URL + " varchar," + 

24                 HistoryBean.TIME + " integer,"+

25                 HistoryBean.NAME + " varchar"+

26                 ")");

27     }

28     

29     /**

30      * 当检测与前一次创建数据库版本不一样时，先删除表再创建新表

31      */

32     @Override

33     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

34         db.execSQL("DROP TABLE IF EXISTS " + TB_NAME);

35         onCreate(db);

36     }

37     

38     /**

39      * 变更列名

40      * @param db

41      * @param oldColumn

42      * @param newColumn

43      * @param typeColumn

44      */

45     public void updateColumn(SQLiteDatabase db, String oldColumn, String newColumn, String typeColumn){

46         try{

47             db.execSQL("ALTER TABLE " +

48                     TB_NAME + " CHANGE " +

49                     oldColumn + " "+ newColumn +

50                     " " + typeColumn

51             );

52         }catch(Exception e){

53             e.printStackTrace();

54         }

55     }

56 

57 }