SQLite使用基础

数据库的增删改查操作，实现对封装了bean的操作。建表：

@Override

publicvoidonCreate(SQLiteDatabasedb){

Stringsql="CREATETABLE"+TABLE_NAME+"("+_ID

+"INTEGERPRIMARYKEYAUTOINCREMENT,"+_USERNAME

+"TEXTNOTNULL,"+_PASSWORD+"TEXT)";

Log.i(TAG,sql);

db.execSQL(sql);

}

增加数据：①利用sql语句

publicvoidadd(Useru){

Stringsql="INSERTINTO"+TABLE_NAME+"("+_USERNAME+","

+_PASSWORD+")VALUES(?,?)";

Log.i(TAG,sql);

db.execSQL(sql,newObject[]{u.getUserName(),u.getPassWord()});

}

②高级做法

publicvoidadd_(Useru){

ContentValuesvalues=newContentValues();

	values.put(_USERNAME,u.getUserName());

	values.put(_PASSWORD,u.getPassWord());

	db.insert(TABLE_NAME,null,values);

}

db.insert(TABLE_NAME,null,values);①参数一：表名②参数二：可选的，一般为空，当values参数为空或者里面没有内容的时候，insert是会失败的(底层数据库不允许插入一个空行)，为了防止这种情况，我们要在这里设置一个列名，到时候如果发现将要插入的行为空行时，就会将你指定的这个列名的值设为null,然后再向数据库中插入。删除数据：①利用sql语句

publicvoiddel(intid){

	Stringsql="DELETEFROM"+TABLE_NAME+"WHERE"+_ID+"=?";

Log.i(TAG,sql);

db.execSQL(sql,newObject[]{id});

}

②高级做法

publicvoiddel_(intid){

	StringwhereClause=_ID+"=?";

	String[]whereArgs={id+""};

	db.delete(TABLE_NAME,whereClause,whereArgs);

}

db.delete(TABLE_NAME,whereClause,whereArgs)参数一：表名参数二：where后面添加的条件，看好格式参数三：条件中？参数的值的数组更改数据：①利用sql

publicvoidupdate(Useru){

	Stringsql="UPDATE"+TABLE_NAME+"SET"+_USERNAME+"=?,"+_PASSWORD+"=?"+"WHERE"+_ID+"=?";

Log.i(TAG,sql);

db.execSQL(sql,

newObject[]{u.getUserName(),u.getPassWord(),u.getId()});

}

②推荐做法

publicvoidupdate_(Useru){

ContentValuesvalues=newContentValues();

	values.put(_USERNAME,u.getUserName());

	values.put(_PASSWORD,u.getPassWord());

	StringwhereClause=_ID+"=?";//可以有多个条件的

	String[]whereArgs={u.getId()+""};

	db.update(TABLE_NAME,values,whereClause,whereArgs);

}

db.update(TABLE_NAME,values,whereClause,whereArgs)：荐做法参数一：表名参数二：更改之后的ContentValues类型的值参数三：条件语句，格式参数四：条件中?号所对应的值查询数据：①sql语句做法

publicList<User>queryAll(){

	List<User>list=newArrayList<User>();

	Stringsql="SELECT*FROM"+TABLE_NAME;

Log.i(TAG,sql);

	Cursorcursor=db.rawQuery(sql,null);

	while(cursor.moveToNext()){

		Useru=newUser();

u.setId(cursor.getInt(cursor.getColumnIndex(_ID)));

u.setUserName(cursor.getString(cursor.getColumnIndex(_USERNAME)));

u.setPassWord(cursor.getString(cursor.getColumnIndex(_PASSWORD)));

list.add(u);

}

	returnlist;

}

②高级用法

publicList<User>queryAll_(){

	List<User>list=newArrayList<User>();

	Cursorcursor=db.query(TABLE_NAME,null,null,null,null,null,

null);

	while(cursor.moveToNext()){

		Useru=newUser();

u.setId(cursor.getInt(cursor.getColumnIndex(_ID)));

u.setUserName(cursor.getString(cursor.getColumnIndex(_USERNAME)));

u.setPassWord(cursor.getString(cursor.getColumnIndex(_PASSWORD)));

list.add(u);

}

	returnlist;

}

db.query(table,columns,selection,selectionArgs,groupBy,having,orderBy)上面都给空，代表就是select*fromuser;参数一：表名参数二：需要查询的字段参数三：筛选的语句，类似于where中的条件参数四：筛选条件中的值参数四：为分组增加条件参数五：分组之后的条件参数六：排序还有三个构造方法。看名称就能看懂。实现分页的功能的查询：

publicCursorquery(intcurrentPage,intpageSize){

	intstart=(currentPage-1)*pageSize;

	Stringlimit=start+","+pageSize;//和sql语句基本一样

	Cursorcursor=db.query(TABLE_NAME,null,null,null,null,null,null,limit);

	returncursor;

}

整体的代码：

importjava.util.ArrayList;

importjava.util.List;

importandroid.content.ContentValues;

importandroid.content.Context;

importandroid.database.Cursor;

importandroid.database.sqlite.SQLiteDatabase;

importandroid.database.sqlite.SQLiteOpenHelper;

importandroid.util.Log;

importcom.mixm.bean.User;

publicclassUserDBHelper{

	privatestaticfinalStringTAG="UserDBHelper";

	privatestaticfinalStringDATABASE_NAME="user.db";

	privatestaticfinalintVERSISON=1;

	privatestaticfinalStringTABLE_NAME="user";

	privatestaticfinalString_ID="id";

	privatestaticfinalString_USERNAME="username";

	privatestaticfinalString_PASSWORD="password";

	privateUserHelperuserHelper;

	privateSQLiteDatabasedb;

	//内部类

	classUserHelperextendsSQLiteOpenHelper{

		publicUserHelper(Contextcontext){

			super(context,DATABASE_NAME,null,VERSISON);

}

@Override

		publicvoidonCreate(SQLiteDatabasedb){

		Stringsql="CREATETABLE"+TABLE_NAME+"("+_ID

		+"INTEGERPRIMARYKEYAUTOINCREMENT,"+_USERNAME

		+"TEXTNOTNULL,"+_PASSWORD+"TEXT)";

	Log.i(TAG,sql);

		db.execSQL(sql);

}

@Override

		publicvoidonUpgrade(SQLiteDatabasedb,intoldVersion,intnewVersion){

}

}

	publicUserDBHelper(Contextcontext){

		userHelper=newUserHelper(context);

		db=userHelper.getWritableDatabase();

}

	//普通

	publicvoidadd(Useru){

	Stringsql="INSERTINTO"+TABLE_NAME+"("+_USERNAME+","

	+_PASSWORD+")VALUES(?,?)";

Log.i(TAG,sql);

db.execSQL(sql,newObject[]{u.getUserName(),u.getPassWord()});

}

	//高级一般做法

	publicvoidadd_(Useru){

	ContentValuesvalues=newContentValues();

		values.put(_USERNAME,u.getUserName());

		values.put(_PASSWORD,u.getPassWord());

		db.insert(TABLE_NAME,null,values);

}

	publicvoiddel(intid){

		Stringsql="DELETEFROM"+TABLE_NAME+"WHERE"+_ID+"=?";

Log.i(TAG,sql);

	db.execSQL(sql,newObject[]{id});

}

	publicvoiddel_(intid){

		StringwhereClause=_ID+"=?";

		String[]whereArgs={id+""};

		db.delete(TABLE_NAME,whereClause,whereArgs);

}

	publicvoidupdate(Useru){

		Stringsql="UPDATE"+TABLE_NAME+"SET"+_USERNAME+"=?,"

				+_PASSWORD+"=?"+"WHERE"+_ID+"=?";

Log.i(TAG,sql);

	db.execSQL(sql,

				newObject[]{u.getUserName(),u.getPassWord(),u.getId()});

}

	publicvoidupdate_(Useru){

	ContentValuesvalues=newContentValues();

		values.put(_USERNAME,u.getUserName());

		values.put(_PASSWORD,u.getPassWord());

		StringwhereClause=_ID+"=?";

		String[]whereArgs={u.getId()+""};

		db.update(TABLE_NAME,values,whereClause,whereArgs);

}

	publicList<User>queryAll(){

		List<User>list=newArrayList<User>();

		Stringsql="SELECT*FROM"+TABLE_NAME;

Log.i(TAG,sql);

		Cursorcursor=db.rawQuery(sql,null);

		while(cursor.moveToNext()){

			Useru=newUser();

	u.setId(cursor.getInt(cursor.getColumnIndex(_ID)));

	u.setUserName(cursor.getString(cursor.getColumnIndex(_USERNAME)));

	u.setPassWord(cursor.getString(cursor.getColumnIndex(_PASSWORD)));

	list.add(u);

}

		returnlist;

}

	publicList<User>queryAll_(){

		List<User>list=newArrayList<User>();

		Cursorcursor=db

				.query(TABLE_NAME,null,null,null,null,null,null);

		while(cursor.moveToNext()){

			Useru=newUser();

	u.setId(cursor.getInt(cursor.getColumnIndex(_ID)));

	u.setUserName(cursor.getString(cursor.getColumnIndex(_USERNAME)));

	u.setPassWord(cursor.getString(cursor.getColumnIndex(_PASSWORD)));

	list.add(u);

}

		returnlist;

}

}