[英]check if row exist with this kind of implementing sqlite db
如果行存在,如何檢查sqlite數據庫? 我實現sqlite db的風格是這樣的
public class EmployeeDBController extends SQLiteOpenHelper {
public EmployeeDBController(Context applicationcontext) {
super(applicationcontext, "registeruser.db", null, 1);
}
public SQLiteDatabase db;
//Creates Table
@Override
public void onCreate(SQLiteDatabase database) {
String query;
query = "CREATE TABLE register ( userId INTEGER PRIMARY KEY, Name text, Age text, Gender text," +
"HomeAddress text, Password text, QRID text, udpateStatus TEXT)";
database.execSQL(query);
}
@Override
public void onUpgrade(SQLiteDatabase database, int version_old, int current_version) {
String query;
query = "DROP TABLE IF EXISTS register";
database.execSQL(query);
onCreate(database);
}
}
例如:我想檢查在sqlite數據庫中是否有“名稱”和“約翰”。
有一個幫助程序函數 ,可以避免被游標弄亂:
public boolean rowExists(String table, String column, String value) {
long count = DatabaseUtils.queryNumEntries(db,
table, column+" = ?", new String[]{ value });
return count > 0;
}
使用這種方法!
public boolean isRowExist(/*YOUR_INPUTS*/){
try {
db = mDBHelper.getReadableDatabase();
String selectQuery = YOUR_SEARCH_QUERY_STATMENT
//You should use YOUR_INPUTS to create a selectQuery that can select the row/rows for you
Cursor c = db.rawQuery(selectQuery, null);
if(c.getCount()>=1){
c.close();
return true;
}
c.close();
return false;
} catch (Exception e) {
return false;
}
}
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