关于android的DB操作

package com.metoo.girls;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

/**
 * @author wbhuang
 * @time 20130912
 * @description 数据库操作封装
 */
public class GirlsDbHelper {
	private static String TAG = "GirlsDbHelper";
	private static GirlsDbHelper girlsDbHelper = null;
	private static DatabaseHelper dbHelper;
	private static SQLiteDatabase db;
	private static final String GRILS_DB_NAME = "girls.db";
	private static final int GIRLS_DB_VERSION = 1;
	private Context context;

	private GirlsDbHelper(Context c) {
		context = c;
	}

	private static class DatabaseHelper extends SQLiteOpenHelper {
		public DatabaseHelper(Context c) {
			super(c, GRILS_DB_NAME, null, GIRLS_DB_VERSION);
		}

		@Override
		public void onCreate(SQLiteDatabase arg0) {
		}

		@Override
		public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
		}
	} 

	public static GirlsDbHelper getInstance(Context c) {
		if (null == girlsDbHelper) {
			girlsDbHelper = new GirlsDbHelper(c);
		}
		return girlsDbHelper;
	}

	/**
	 * 打开数据库
	 */
	public void open() {
		Log.v(TAG, "open");
		dbHelper = new DatabaseHelper(context);
		db = dbHelper.getWritableDatabase();
	}

	/**
	 * 关闭数据库
	 */
	public void close() {
		Log.v(TAG, "close");
		db.close();
		dbHelper.close();
	}

	/**
	 * 插入数据
	 * @param tblName 表名
	 * @param values 要插入的列对应值
	 * @return
	 */
	public long insert(String tblName, ContentValues values) {
		return db.insert(tblName, null, values);
	}

	/**
	 * 删除数据
	 * @param tblName 表名
	 * @param deleteCondition 删除条件
	 * @param deleteArgs 如果deleteCondition中有"?"号，将用次数组替换
	 * @return
	 */
	public long delete(String tblName, String deleteCondition, String[] deleteArgs) {
		return db.delete(tblName, deleteCondition, deleteArgs);
	}

	/**
	 * 更新数据
	 * @param tblName 表名
	 * @param values 要更新的列
	 * @param selection 更新的条件
	 * @param selectArgs 如果selection中有"?"将由此数组中的值替换
	 * @return
	 */
	public long update(String tblName, ContentValues values, String selection, String[] selectArgs) {
		return db.update(tblName, values, selection, selectArgs);
	}

	/**
	 * 查询多行数据
	 * @param tblName 表名
	 * @param columns 查询的列
	 * @param selection 查询条件
	 * @param selectionArgs 如果selection中有"?"将由此数组中的值替换
	 * @return
	 */
	public Cursor queryList(String tblName, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy) {
		return db.query(tblName, columns, selection, selectionArgs, groupBy, having, orderBy);
	}

	/**
	 * 查询单行数据
	 * @param tblName 表名
	 * @param columns 查询的列
	 * @param selection 查询条件
	 * @param selectionArgs 如果selection中有"?"将由此数组中的值替换
	 * @return
	 */
	public Cursor queryOne(String tblName, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy) {
		Cursor cursor = db.query(tblName, columns, selection, selectionArgs, groupBy, having, orderBy);
		if (cursor != null) {
			cursor.moveToFirst();
		}
		return cursor;
	}

	/**
	 * 执行SQL语句
	 * @param sql
	 */
	public void execSQL(String sql){
		db.execSQL(sql);
	}  

	/**
	 * 判断表是否存在
	 * @param tableName
	 * @return
	 */
	public boolean isTableExist(String tableName){
		boolean result = false;
		if(tableName == null){
			return false;
		}
		try {
			Cursor cursor = null;
			String sql = "select count(1) as c from sqlite_master where type ='table' and name ='"+tableName.trim()+"' ";
			cursor = db.rawQuery(sql, null);
			if(cursor.moveToNext()){
				int count = cursor.getInt(0);
				if(count > 0){
					result = true;
				}
			}
			cursor.close();
		} catch (Exception e) {
			Log.e(TAG, "isTableExist exception");
		}
		return result;
	}  

	 /**
	  * 判断是否存在某字段(要先判断表是否存在)
	  * @param tabName 表名
	  * @return
	  */
	public boolean isColumnExist(String tableName,String columnName){
		boolean result = false;
		if(tableName == null) {
			return false;
		}
		try {
			Cursor cursor = null;
			String sql = "select count(1) as c from sqlite_master where type ='table' and name ='"+tableName.trim()+"' and sql like '%"+ columnName.trim() +"%'" ;
			cursor = db.rawQuery(sql, null);
			if(cursor.moveToNext()){
				int count = cursor.getInt(0);
				if(count > 0){
					result = true;
				}
			}
			cursor.close();
		} catch (Exception e) {
			Log.e(TAG, "isColumnExist exception");
		}
		return result;
	}  

}

package com.metoo.girls;

import android.content.ContentValues;
import android.database.Cursor;
import android.test.AndroidTestCase;
import android.util.Log;
/**
 * 单元测试操作sqlLite的各种sql
 */
public class GirlsDbHelperTest extends AndroidTestCase{
	/**
	 * 创建表
	 * @throws Exception
	 */
	public void createTable() throws Exception{
		GirlsDbHelper dbHelper = GirlsDbHelper.getInstance(this.getContext());
		dbHelper.open();
		String deleteSql = "drop table if exists user ";
		dbHelper.execSQL(deleteSql);
		 //id是自动增长的主键，username和 password为字段名， text为字段的类型
		String sql = "CREATE TABLE user (id integer primary key autoincrement, username text, password text)";
		dbHelper.execSQL(sql);
		dbHelper.close();
	}

	/**
	 * 插入数据
	 * @throws Exception
	 */
	public void insert() throws Exception{
		GirlsDbHelper dbHelper = GirlsDbHelper.getInstance(this.getContext());
		dbHelper.open();
		ContentValues values =  new ContentValues();  //相当于map
		values.put("username", "test");
		values.put("password", "123456");
		dbHelper.insert("user", values);
		dbHelper.close();
	}

	/**
	 * 更新数据
	 * @throws Exception
	 */
	public void update() throws Exception{
		GirlsDbHelper dbHelper = GirlsDbHelper.getInstance(this.getContext());
		dbHelper.open();
		ContentValues initialValues = new ContentValues();
		initialValues.put("username", "changename");  //更新的字段和值
		dbHelper.update("user", initialValues, "id = '1'", null);   //第三个参数为 条件语句
		dbHelper.close();
	}

	/**
	 * 删除数据
	 * @throws Exception
	 */
	public void delete() throws Exception{
		GirlsDbHelper dbHelper = GirlsDbHelper.getInstance(this.getContext());
		dbHelper.open();
		String testId = "1";
		dbHelper.delete("user", "id = '"+ testId +"'", null);
		dbHelper.close();
	}

	/**
	 * 增加字段
	 * @throws Exception
	 */
	public void addColumn() throws Exception{
		GirlsDbHelper dbHelper = GirlsDbHelper.getInstance(this.getContext());
		dbHelper.open();
		String updateSql = "alter table user add company text";
		dbHelper.execSQL(updateSql);
	}

	/**
	 * 查询列表
	 * @throws Exception
	 */
	public void selectList() throws Exception{
		GirlsDbHelper dbHelper = GirlsDbHelper.getInstance(this.getContext());
		dbHelper.open();
		Cursor returnCursor = dbHelper.queryList("tbl_sexy_state", new String[] {"id", "index", "unlocked"}, "index = ", null,null, null, "id desc");
		while(returnCursor.moveToNext()){
			String id = returnCursor.getString(returnCursor.getColumnIndexOrThrow("id"));
			String username = returnCursor.getString(returnCursor.getColumnIndexOrThrow("username"));
			String password = returnCursor.getString(returnCursor.getColumnIndexOrThrow("password"));
		}
	}

	/**
	 * 某条信息
	 * @throws Exception
	 */
	public void selectInfo() throws Exception{
		GirlsDbHelper dbHelper = GirlsDbHelper.getInstance(this.getContext());
		dbHelper.open();
		Cursor returnCursor = dbHelper.queryList("user",new String[] {"id","username", "password"}, "id = '1'", null,null, null, "id desc");
		if (returnCursor.getCount() > 0) {
			returnCursor.moveToFirst();
			String id = returnCursor.getString(returnCursor.getColumnIndexOrThrow("id"));
			String username = returnCursor.getString(returnCursor.getColumnIndexOrThrow("username"));
			String password = returnCursor.getString(returnCursor.getColumnIndexOrThrow("password"));
		}
	}
}