I have to insert a lot of rows in my SQLite Database and for some tables
a specific value of each row has to be converted into an other using the value of an other table.
Actually, I have this function which is working well:
public void myFunction( String tableName, String attrName, ContentValues currentVal ) {
SQLiteDatabase database = this.getReadableDatabase();
Cursor c = database.rawQuery("SELECT colName FROM "+tableName+" WHERE "+tableName+".otherColName = " + currentVal.getAsString(attrName), null);
Long realValue = null;
if( c.moveToFirst() ) {
realValue = c.getLong(0);
}
if( c != null ) c.close();
currentVal.put( attrName, realValue );
}
But, this is really time consumimg because of this part:
if( c.moveToFirst() ) {
realValue = c.getLong(0);
}
So I wanted to know if there's a way to set the query directly in the value of the ContantValue like this:
currentVal.put( attrName, "SELECT colName FROM "+tableName+" WHERE "+tableName+".otherColName = " + currentVal.getAsString(attrName));
and the query will be executed at the same time as the insert query in order to replace the value.
Thank you beforehand!
No, ContentValues is just a wrapper of a hash map for the data. You can try to use index to accelerate the query.
I want to check the records are available or not in my Sqlite table. I tried but the cursor is always return 1 value even if the SQlite databse table is empty, no any record in table. Why return one? How to solve this issue?
dbhelper = new MyDbHelper(this);
SQLiteDatabase db = dbhelper.getWritableDatabase();
String count = "select count(*) from ActivityObjectList";
Cursor mcursor = db.rawQuery(count, null);
mcursor.moveToFirst();
int icount = mcursor.getInt(0);
if(icount>0)
{
Log.e("Record does not found","");
//leav
}
else
{
Log.e("Record is exists !!","");
//populate table
}
Use mcursor.getCount() to check number of rows.
I am trying to get the last 3 entries made to the database. Im using the following code but im only getting the last entry not the last 3.
String query = "Select * from " + TABLE_DETAILS + " DESC limit 3;";
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(query, null);
if (cursor.moveToFirst()) {
cursor.moveToFirst();
System.out.println(Integer.parseInt(cursor.getString(2)));
cursor.close();
} else {
}
db.close();
Thanks
You'll need to loop with the cursor to get all result rows, e.g. instead of
if (cursor.moveToFirst()) {
...
loop like this
while (cursor.moveToNext()) {
System.out.println(cursor.getString(2));
}
cursor.close();
To change the ordering, add ORDER BY <expression> to your query, for example
SELECT ... ORDER BY _id DESC LIMIT 3
I'm trying a simple SQL Command wihtin my Android-App, to get the age of a selected Person:
public int getAge(){
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM persons WHERE name =? " + MainActivity.selectedPerson.getText().toString(), null);
int age = cursor.getInt(3); // column with ages
cursor.close();
db.close();
return age;
}
But when I run my app, it crashes when I call the function getAge(). I get the following Error:
SQLiteException: no such column: Max: , while compiling: SELECT * FROM persons WHERE name = Max
I don't get it. There is the name "Max" in the table. What am I doing wrong? Thanks in advance.
Edit 2:
With this one:
Cursor cursor = db.rawQuery("SELECT name FROM persons WHERE name = '" + MainActivity.selectedPerson.getText().toString() + "'", null);
I get a different error:
08-27 19:43:47.573: E/AndroidRuntime(6161): android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 1
what does this mean?
You should consider using the selectionArgs parameter of rawQuery() to prevent SQL Injection Attacks:
Cursor cursor = db.rawQuery("SELECT * FROM persons WHERE name = ?", new String[] { MainActivity.selectedPerson.getText().toString() });
Also you only need one column so rather than wasting resources by selecting them all with *, you should just select the one column:
Cursor cursor = db.rawQuery("SELECT age FROM persons WHERE name = ?", new String[] { MainActivity.selectedPerson.getText().toString() });
Hope that helps!
All together it should look like:
public int getAge(){
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT age FROM persons WHERE name = ?", new String[] { MainActivity.selectedPerson.getText().toString() });
int age;
// Check if you have a valid result and move to the first row to read it
if(cursor.moveToFirst())
age = cursor.getInt(0);
// Prevent a crash if there is no data for this name
else
age = 0;
cursor.close();
db.close();
return age;
}
Chan ge the 3rd line of your program:
Cursor cursor = db.rawQuery("SELECT * FROM persons WHERE name =? " + MainActivity.selectedPerson.getText().toString(), null);
to this:
Cursor cursor = db.rawQuery("SELECT * FROM persons WHERE name = ?", new String[] { MainActivity.selectedPerson.getText().toString()} );
Try this:
public int getAge(){
int age;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM persons WHERE name = '" + MainActivity.selectedPerson.getText().toString()+"'",null);
if(cursor.moveToFirst())
{
age = cursor.getInt(3); // column with ages
}
cursor.close();
db.close();
return age;
}
You missed the single quotes (' ') in your sql command. That's why MAX was taken as a column and not as a value.
I am trying to get the last inserted rowid from a sqlite database in Android. I have read a lot of posts about it, but can't get one to work.
This is my method:
public Cursor getLastId() {
return mDb.query(DATABASE_TABLE, new String[] {KEY_WID}, KEY_WID + "=" + MAX(_id), null, null, null, null, null);}
I have tried with MAX, but I must be using it wrong. Is there another way?
Well actually the SQLiteDatabase class has its own insert method which returns the id of the newly created row. I think this is the best way to get the new ID.
You can check its documentation here.
I hope this helps.
Use
SELECT last_insert_rowid();
to get the last inserted rowid.
If you are using AUTOINCREMENT keyword then
SELECT * from SQLITE_SEQUENCE;
will tell you the values for every table.
To get the last row from the table..
Cursor cursor = theDatabase.query(DATABASE_TABLE, columns,null, null, null, null, null);
cursor.moveToLast();
Use moveToLast() in Cursor interface.
From android.googlesource.com
/**
* Move the cursor to the last row.
*
* <p>This method will return false if the cursor is empty.
*
* #return whether the move succeeded.
*/
boolean moveToLast();
Simple example:
final static String TABLE_NAME = "table_name";
String name;
int id;
//....
Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_NAME, null);
if(cursor.moveToLast()){
//name = cursor.getString(column_index);//to get other values
id = cursor.getInt(0);//to get id, 0 is the column index
}
Or you can get the last row when insertion(Which is #GorgiRankovski have mentioned):
long row = 0;//to get last row
//.....
SQLiteDatabase db= this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COLUMN_NAME, name);
row = db.insert(TABLE_NAME, null, contentValues);
//insert() returns the row ID of the newly inserted row, or -1 if an error occurred
Also their is a multiple ways you can do this using query:
One is expressed by #DiegoTorresMilano
SELECT MAX(id) FROM table_name. or to get all columns values SELECT * FROM table_name WHERE id = (SELECT MAX(id) FROM table_name).
If your PRiMARY KEY have sat to AUTOINCREMENT, you can SELECT vaules occording to max to min and limit the rows to 1 using SELECT id FROM table ORDER BY column DESC LIMIT 1
(If you want each and every value, use * instead of id)
If you want the last_insert_id just afert a insert you can use that :
public long insert(String table, String[] fields, String[] vals )
{
String nullColumnHack = null;
ContentValues values = new ContentValues();
for (int i = 0; i < fields.length; i++)
{
values.put(fields[i], vals[i]);
}
return myDataBase.insert(table, nullColumnHack, values);
}
The insert method returns the id of row just inserted or -1 if there was an error during insertion.
long id = db.insert("your insertion statement");
db is an instance of your SQLiteDatabase.
Try this:
public Cursor getLastId() {
return mDb.query(DATABASE_TABLE, new String[] { **MAX(id)** }, null, null, null, null, null, null);}
/**
* #return
*/
public long getLastInsertId() {
long index = 0;
SQLiteDatabase sdb = getReadableDatabase();
Cursor cursor = sdb.query(
"sqlite_sequence",
new String[]{"seq"},
"name = ?",
new String[]{TABLENAME},
null,
null,
null,
null
);
if (cursor.moveToFirst()) {
index = cursor.getLong(cursor.getColumnIndex("seq"));
}
cursor.close();
return index;
}
I use this
public int lastId(){
SQLiteDatabase db =
this.getReadableDatabase();
Cursor res = db.rawQuery( "select * from resep", null );
res.moveToLast();
return res.getInt(0);
}
In your DbHelper class,
public long getLastIdFromMyTable()
{
SQLiteDatabase db = this.getReadableDatabase();
SQLiteStatement st = db.compileStatement("SELECT last_insert_rowid() from " + MY_TABLE);
return st.simpleQueryForLong();
}