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how to fetch data from sqlite by name

I just started learning of android and come to section of Database and I inserted same record in it but now I want to fetch data from database only by name and display it in textview.
Help me
Thank You in advance

Please follow developer document.
https://developer.android.com/training/basics/data-storage/databases.html
SQLiteDatabase db = mDbHelper.getReadableDatabase();
// Define a projection that specifies which columns from the database
// you will actually use after this query.
String[] projection = {
FeedEntry._ID,
FeedEntry.COLUMN_NAME_TITLE,
FeedEntry.COLUMN_NAME_SUBTITLE
};
// Filter results WHERE "title" = 'My Title'
String selection = FeedEntry.COLUMN_NAME_TITLE + " = ?";
String[] selectionArgs = { "My Title" };
// How you want the results sorted in the resulting Cursor
String sortOrder =
FeedEntry.COLUMN_NAME_SUBTITLE + " DESC";
Cursor cursor = db.query(
FeedEntry.TABLE_NAME, // The table to query
projection, // The columns to return
selection, // The columns for the WHERE clause
selectionArgs, // The values for the WHERE clause
null, // don't group the rows
null, // don't filter by row groups
sortOrder // The sort order
);

You access data by using a query which returns a Cursor.
A Cursor is like a spreadsheet table that contains columns and rows.
You tell the query what columns you want and imply the rows that will be returned via an optional WHERE statement.
The simplest of queries is base upon the SQL SELECT * FROM <table>;. This will select all columns (i.e. * means all columns) from the table as specified by <table> ( where would be replaced by a valid table name).
If you want specific columns then ***`` should be replaced with a comma delimited list e.g.SELECT name, address FROM would return a **Cursor** containing all the rows from the table with only the **name** and **address** columns from the table specified by`.
If you want to filter the rows returned then you can add a WHERE clause. e.g. SELECT name,address FROM <table> WHERE name = 'Fred', would return a Cursor containing only the rows that have Fred as the name column with only the name and address columns.
You cannot just type the SQL statments you need to either use the SQLiteDatabase rawQuery or query methods if you need to return a cursor.
Using rawQuery
rawQuery takes two parameters, the first being the SQL as a string, the second optional arguments (not covered here, so null will be used).
To obtain a Cursor with columns name and address and with only rows that have Fred you could use, assuming the table is called mytable :-
`Cursor mycursor = db.rawQuery("SELECT name,address FROM mytable WHERE name = 'Fred'";);`
where db is an instance of an SQLiteDatabase object.
However, rawQuery is not recommended as it is open SQL injection. rather it is recommended only for situations where it has to be used.
Using query
query has a number of overload variations as can be found here SQLiteDatabase.
For this example query(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy) will be used.
String table, is the name of the table to be queried.
String[] columns, is an array of column names.
String selection is the where clause (null for no where clause).
String[] selectionArgs is an array of arguments that replace the ? placeholder.
The rest of the parameters will be null as these are features that are not being utilised.
As such the code could be :-
String tablename = "mytable";
String[] columns = {"name", "address"};
String whereclause = "name=?"; //note use of placeholder ?
String[] whereargs = {"Fred"};
Cursor mycursor = db.query(tablename,
columns,
whereclause,
whereargs,
null,null,null
);
where db is an instance of an SQLiteDatabase object.
Accessing the Cursor
mycursor contains the data or perhaps not if there isn't a column with the name Fred.
The number of rows in the cursor can be obtained by using:-
int rowsincursor = mycursor.getCount();
Note! A returned Cursor will not be null. (a very common mistake)
To access the data you have to move through the Cursor. Initially the Cursor is before the first row. If you only expect or want the only/first row then you can use the Cursor moveToFirst method.
See Cursor for more move... methods etc
Once the Cursor is appropriately positioned you can use Cursor get methods to get the data. e.g. getString(int columnindex) will return the data as a String. columnindex is a 0 based offset of the column to be accessed. Using the Cursor's getColumnIndex(String columnname) can be used to eliminate errors made by miscalculating offsets.
As such the following could be used to set a TextView (note intentionally over cautious)
if (mycursor.getCCount() > 0) {
if (mycursor.moveToFirst()) {
mytextview.setText(mycursor.getString(mycursor.getColumnIndex("name")));
}
}
mycursor.close() // You should always close a cursor when done with it.

How to query using SQLiteDatabase.query

How can I make query using SQLiteDatabase.query ?
"Select * from table where col1 = something AND col2 IS NOT NULL"
I tried it by putting the col2 with a =? in selection String and NOT NULL in selection argument but it doesn't work.
Please tell me where m going wrong.

selectionArgs is an array of strings, and can be used only for string values.
When you use col2 = ? with the string NOT NULL, you are telling the database to check if the column's value is the eight-character string "NOT NULL".
You must write col2 IS NOT NULL directly into the selection string:
db.query("MyTable", null,
"col1 = ? AND col2 IS NOT NULL",
new String[] { "something" },
null, null, null);

You can use Cursor and rawQuery
Cursor c=db.rawQuery(your_query,null)

public Cursor query (String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy)
Query the given table, returning a Cursor over the result set.
Parameters
table The table name to compile the query against.
columns
A list of which columns to return. Passing null will return all columns, which is discouraged to prevent reading data from storage that isn't going to be used.
selection
A filter declaring which rows to return, formatted as an SQL WHERE clause (excluding the WHERE itself). Passing null will return all rows for the given table.
selectionArgs
You may include ?s in selection, which will be replaced by the values from selectionArgs, in order that they appear in the selection. The values will be bound as Strings.
groupBy
A filter declaring how to group rows, formatted as an SQL GROUP BY clause (excluding the GROUP BY itself). Passing null will cause the rows to not be grouped.
having
A filter declare which row groups to include in the cursor, if row grouping is being used, formatted as an SQL HAVING clause (excluding the HAVING itself). Passing null will cause all row groups to be included, and is required when row grouping is not being used.
orderBy
How to order the rows, formatted as an SQL ORDER BY clause (excluding the ORDER BY itself). Passing null will use the default sort order, which may be unordered.
So you can try like this
String[] args = { "first string", "second#string.com" };
Cursor cursor = db.query("TABLE_NAME", null, "name=? AND email=?", args, null,null,null);

adding DISTINCT keyword to query() with SQLite in Android

the difference between query() and rawQuery() in SQLite when making more complex SQL queries.
for example
i want to use the SQL keyword DISTINCT, so I don't get any duplicates returned from the database.
i understand how to use rawQuery() method, that way you can put an actual SQL query statement in the method. in this way i can make a standard SQL statement with rawQuery. it would be easy to add the DISTINCT keyword to any SQL statement when using rawQuery()
however, when using the query() method as shown here in this code, I can't just use regular SQL statements. in this case, how would i make a query with the DISTINCT keyword as part of the query? or something with the same functionality?
// get info from country table
public String[] getCountries(int numberOfRows) {
String[] columns = new String[]{COUNTRY_NAME};
String[] countries = new String[numberOfRows];
int counter = 0;
Cursor cursor = sqLiteDatabase.query(COUNTRY_TABLE, columns,
null, null, null, null, null);
if (cursor != null){
while(cursor.moveToNext()){
countries[counter++] = cursor.getString(cursor.getColumnIndex(COUNTRY_NAME));
}
}
return countries;
}

Instead of the...
public Cursor query(String table, String[] columns, String selection,
String[] selectionArgs, String groupBy, String having,
String orderBy)
...method you're using, just use the...
public Cursor query (boolean distinct, String table, String[] columns,
String selection, String[] selectionArgs, String groupBy,
String having, String orderBy, String limit)
...overload and set distinct to true.
The Android docs seem a bit hard to direct link, but the doc page describing both is here.

you can use this,
Cursor cursor = db.query(true, YOUR_TABLE_NAME, new String[] { COLUMN1 ,COLUMN2, COLUMN_NAME_3 }, null, null, COLUMN2, null, null, null);
Here first parameter is used to set the DISTINCT value i.e if set to true it will return distinct column value.
and sixth parameter denotes column name which you want to GROUP BY.

You should use another QUERY function with first DISTINCT boolean parameter set to TRUE
public Cursor query (boolean distinct, String table,...)

this is the function i used in my app for getting distict name from a group table hope you get an idea ,have a look at it.only distinct values will be fetched if the column contains same names
public ArrayList<String> getGroupNames() {
ArrayList<String> groups = new ArrayList<>();
SQLiteDatabase db = this.getReadableDatabase();
String[] projection = {COLUMN_GROUP_NAME};
//select distinct values for group name from group table
Cursor cursor = db.query(true,GROUPS_TABLE_NAME, projection, null, null, COLUMN_GROUP_NAME, null, null,null);
if (cursor.moveToFirst()) {
do {
String group=cursor.getString(cursor.getColumnIndexOrThrow(COLUMN_GROUP_NAME));
groups.add(group);
Log.d("group",group+"gp");
}while (cursor.moveToNext());
}
return groups;
}

how to use rawQuery in android

I have a database table with 3 columns: id, name, permission.
It looks like this:
1 Comics fun
2 Communication talk
3 Comics watch
I am trying to get the permission where the name is comics. I am using the following code in my database class(AppData.java):
private final static String DB_NAME = "safety_app_database"; // the name of our database
private final static int DB_VERSION = 1; // the version of the database
// the names for our database columns
private final String TABLE_NAME = "permissions_table";
private final String ID = "id";
private final String NAME = "name";
private final String PERMISSION = "permission";
and the method
public Cursor getData(){
return db.rawQuery("SELECT permission FROM permissions_table WHERE name = 'Comics', null);
}
and I'm calling this in my main class (safety.java). AppData is referencing AppData.java
appData.getData();
Is this the correct way to do it? I am unsure, and it is giving me an error whenever I try to call the sql query.

One typo mistake, you are not closing sql string with ". try this.
return db.rawQuery("SELECT permission FROM permissions_table WHERE name = 'Comics' ", null);
[EDIT: JAR belongs to 'Android 2.2' which does not allow modifications to source attachments on its entries]
The Jar of this class file blongs to container Android 2.0.1 which does not allow modifications

There is no need for a raw query. You can use one of the recommended SQLiteDatabase query methods and it would look like this:
db.query("permissions_table", new String [] {permission}, "name = \'Comics\'", null, null, null, null);

Try the following approach:
public Cursor getData(String arg) {
return db.rawQuery("SELECT permission FROM `permissions_table` WHERE name ="+arg, null);
}
Then just call the above method with the right parameter like this:
Cursor cursor;
cursor = getData ( "Comic" );

To execute queries, there are two methods: Execute db.rawQuery method Execute db.query method To execute a raw query to retrieve all departments:
Cursor getAllDepts()
{
SQLiteDatabase db=this.getReadableDatabase();
Cursor cur=db.rawQuery("SELECT "+colDeptID+" as _id,
"+colDeptName+" from "+deptTable,new String [] {});
return cur;
}
The rawQuery method has two parameters: String query: The select statement String[] selection args: The arguments if a WHERE clause is included in the select statement Notes The result of a query is returned in Cursor object. In a select statement if the primary key column (the id column) of the table has a name other than _id, then you have to use an alias in the form SELECT [Column Name] as _id cause the Cursor object always expects that the primary key column has the name _id or it will throw an exception . Another way to perform a query is to use a db.query method. A query to select all employees in a certain department from a view would be like this:
public Cursor getEmpByDept(String Dept) {
SQLiteDatabase db=this.getReadableDatabase();
String [] columns=new String[]{"_id",colName,colAge,colDeptName};
Cursor c=db.query(viewEmps, columns, colDeptName+"=?",
new String[]{Dept}, null, null, null);
return c;
}
The db.query has the following parameters: String Table Name: The name of the table to run the query against String [ ] columns: The projection of the query, i.e., the columns to retrieve String WHERE clause: where clause, if none pass null String [ ] selection args: The parameters of the WHERE clause String Group by: A string specifying group by clause String Having: A string specifying HAVING clause String Order By by: A string Order By by clause

Android sql query using WHERE clause

Dear Stack Overflow Community,
I have a question regarding how to incorporate a WHERE clause when querying a sql database in Android. My goal is to return specific records from my database where the date picked by a datepicker matches the date stored.
Here is my code:
private static String datePickerDate = "3/29/2011";
private static String[] FROM = { _ID, NAME, PRICE, DATE, TIME };
private static String ORDER_BY = TIME + " DESC ";
private static String WHERE = DATE + "is like " + datePickerDate;
private Cursor getEvents(){
// Perform a managed Query. The Activity will handle closing
// and re-querying the cursor when needed
SQLiteDatabase db = events.getReadableDatabase();
Cursor cursor = db.query(TABLE_NAME, FROM, null, null, null, null, ORDER_BY);
startManagingCursor(cursor);
return cursor;
}
My questions are thus:
Where does my "WHERE" statement go?
And is my "WHERE" statement correct?
The documentation I found for db.query doesn't specify if a "WHERE" clause can be used, it just specifies that a "HAVING" clause is possible, but I don't quite think that's what I'm wanting.
db.query(table, columns, selection, selectionArgs, groupBy, having, orderBy)

The selection represents your WHERE clause.
From the doc
selection A filter declaring which
rows to return, formatted as an SQL
WHERE clause (excluding the WHERE
itself). Passing null will return all
rows for the given table.
So you can try this (untested):
private static String WHERE = "DATE like ?";
db.query(table, columns, WHERE , new String[] { datePickerDate }, groupBy, having, orderBy)

If you want to use the WHERE clause, I would suggest using the raw query function in the SQLiteDatabase class, shown here.
This way, you can have the raw query typed out (or in segments) as if you were doing it naturally with SQL.
EDIT: On a side note, the "selection" parameter of the query() function corresponds to the WHERE clause, as noted here

About where you're "WHERE" goes - look here
And regarding the second part, I think you miss the qouts before and after the value, it should be .. like '3/29/2011' and not .. is like 3/29/2011