android数据库操作
packagecom.tcl.kang;
importandroid.content.ContentValues;
importandroid.content.Context;
importandroid.database.Cursor;
importandroid.database.sqlite.SQLiteDatabase;
importandroid.database.sqlite.SQLiteOpenHelper;
publicclassDatabaseHelperextendsSQLiteOpenHelper
{
privatestaticfinalStringname="mydatabase";
privatestaticfinalStringTABLE_name="tb_test";
privatestaticfinalintVERSION=1;
privateStringTABLE_NUM="_num";
privateStringTABLE_DATA="_data";
publicDatabaseHelper(Contextcontext)
{
super(context,NAME,null,VERSION);
//TODOAuto-generatedconstructorstub
}
@Override
publicvoidonCreate(SQLiteDatabasedb)
{
//TODOAuto-generatedmethodstub
Stringsql="CREATETABLE"
+TABLE_NAME
+"(_idINTEGERPRIMARYKEYAUTOINCREMENT,_numtext,_datatext)";
db.execSQL(sql);//需要异常捕获
}
@Override
publicvoidonUpgrade(SQLiteDatabasedb,intoldVersion,intnewVersion)
{
//TODOAuto-generatedmethodstub
Stringsql="droptable"+"tb_test";
db.execSQL(sql);
onCreate(db);
}
/**
*添加数据
*/
publiclonginsert(Stringnum,Stringdata)
{
SQLiteDatabasedb=getWritableDatabase();//获取可写SQLiteDatabase对象
//ContentValues类似map，存入的是键值对
ContentValuescontentValues=newContentValues();
contentValues.put(TABLE_NUM,num);
contentValues.put(TABLE_DATA,data);
returndb.insert(TABLE_NAME,null,contentValues);
}
/**
*/**删除记录
*
*@param_id
*/
publicvoiddelete(Stringid)
{
SQLiteDatabasedb=getWritableDatabase();
db.delete(TABLE_NAME,"_id=?",newString[]{id});
}
/**
*更新记录的，跟插入的很像
*/
publicvoidupdate(String_id,Stringnum,Stringdata){
SQLiteDatabasedb=getWritableDatabase();
ContentValuescontentValues=newContentValues();
contentValues.put(TABLE_NUM,num);
contentValues.put("TABLE_DATA",data);
db.update(TABLE_NAME,contentValues,
"_id=?",
newString[]{_id});
}
/**
*查询所有数据
*@returnCursor
*/
publicCursorselect(){
SQLiteDatabasedb=getReadableDatabase();
returndb.query(
TABLE_NAME,
newString[]{"_id",TABLE_NUM,TABLE_DATA},
null,
null,null,null,"_iddesc");//desc降序排列,asc升序排列
}
}