设计了一张表,三个属性,一个为ID,一个为Location,一个为Feature,没有设置约束,只要三列的值不完全一样即可.现在我要按照ID分组,然后每组取出一行,这一行必须满足的条件为该行在所在组的Location值为最小,请问该怎么做.下面是几次失败的尝试Cursor c=read.query(DatabaseHelper.TABLENAME_2,
new String[]{"ID","Location","Feature","MIN(Location) "},null,null,"ID","Location=Min(Location)","ID ASC");//取出所有病毒的第一段特征码.
Cursor c=read.query(DatabaseHelper.TABLENAME_2,
new String[]{"ID","Location","Feature","MIN(Location) M"},null,null,"ID","Location=M","ID ASC");//取出所有病毒的第一段特征码
我希望使用query方法来达成目的.SQLiteJava分组 取最小 query
new String[]{"ID","Location","Feature","MIN(Location) "},null,null,"ID","Location=Min(Location)","ID ASC");//取出所有病毒的第一段特征码.
Cursor c=read.query(DatabaseHelper.TABLENAME_2,
new String[]{"ID","Location","Feature","MIN(Location) M"},null,null,"ID","Location=M","ID ASC");//取出所有病毒的第一段特征码
我希望使用query方法来达成目的.SQLiteJava分组 取最小 query
Cursor c = read.execSQL("select ID,Location,Feature from "+DatabaseHelper.TABLENAME_2+"GroupBy ID ASC Having Location=MIN(Location)");