为什么数据类型不匹配,为什么在调用createRecords方法时,行的插入是(name,_id)而不是(_id,name)?
package com.caldroidsample;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import static android.R.attr.text;
import static android.R.id.primary;
import static com.caldroidsample.R.id.email;
public class MyDatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "DBName";
private static final int DATABASE_VERSION = 2;
// Database creation sql statement
private static final String DATABASE_CREATE = "create table MyEmployees( _id integer primary key, name varchar(255) not null);";
public MyDatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Method is called during creation of the database
@Override
public void onCreate(SQLiteDatabase database) {
database.execSQL(DATABASE_CREATE);
}
// Method is called during an upgrade of the database,
@Override
public void onUpgrade(SQLiteDatabase database,int oldVersion,int newVersion){
Log.w(MyDatabaseHelper.class.getName(),
"Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
database.execSQL("DROP TABLE IF EXISTS MyEmployees");
onCreate(database);
}
}
这是MyDB.java类
package com.caldroidsample;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
public class MyDB{
private MyDatabaseHelper dbHelper;
public SQLiteDatabase database;
public final static String EMP_TABLE="MyEmployees"; // name of table
public final static String EMP_ID="_id"; // id value for employee
public final static String EMP_NAME="name"; // name of employee
public final static String EMP_EMAIL="email"; // email of employee
public final static String EMP_ADDRESS="address";
public final static String EMP_GENDER="gender";
/**
*
* @param context
*/
public MyDB(Context context){
dbHelper = new MyDatabaseHelper(context);
database = dbHelper.getWritableDatabase();
}
public long createRecords(String id, String name){
ContentValues values = new ContentValues();
values.put(EMP_NAME, name);
values.put(EMP_ID, id);
return database.insert(EMP_TABLE, EMP_ID, values);
}
public Cursor selectRecords() {
String[] cols = new String[] {EMP_ID, EMP_NAME};
Cursor mCursor = database.query(true, EMP_TABLE,cols,null
, null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor; // iterate to get each value.
}
}
编辑:我将_id的整数类型更改为varchar(255),但我仍然得到相同的错误。
答案 0 :(得分:0)
我相信您收到数据类型不匹配错误,因为您已将列_id
创建为integer
,并且您正尝试在该列中插入字符串。
尝试values.put(EMP_ID, Integer.parseInt(id));
或只是将整数作为参数传递给createRecords
方法
我不理解您关于(_id, name)
和(name, _id)
的问题的最后部分,但如果您指的是未在values
内保留订单,那是因为它是HashMap中。
还有一件事,当您调用database.insert(EMP_TABLE, EMP_ID, values);
时,如果您确定nullColumnHack
不为空,则不需要在values
参数中传递任何内容。