I have a SQLite table that contains only the _id:
"create table rule (_id integer primary key);";
When running this set of commands:
ContentValues initialValues = new ContentValues();
mDb.insert(TABLE, null, initialValues)
I obtain the following exception:
android.database.sqlite.SQLiteException: near "null": syntax error (code 1): , while compiling: INSERT INTO rule(null) VALUES (NULL)
The initial error occurs because ContentValues cannot be empty. Android provides a convenience parameter called nullColumnHack that allows you to pass a single column with the value null, to bypass this problem.
However this doesn't apply in my case because the row id (_id) cannot be null! Based on the syntax found in the SQLite language docs, I would like to be able to run the SQLite code:
INSERT INTO rule DEFAULT VALUES;
How can i achieve something like this using the android insert method? Or is there something I need to add to my create statement?
UPDATE: In the situation where a table contains ONLY a rowid, the proper syntax is to use INSERT INTO __ DEFAULT VALUES.
The sqlite insert method listed in android does not support DEFAULT VALUES as an option.
A bug has been filed with google and to get support for default values the following commands would need to be executed:
mDb.execSQL("INSERT INTO rule DEFAULT VALUES;");
Cursor c = mDb.rawQuery("SELECT last_insert_rowid()",null);
c.moveToFirst();
int rowid = c.getInt(0);
As stated in the accepted answer, we can get around this (and DEFAULT VALUES) by using nullHackColumn and assigning the row id (_id) to null and letting SQLite make the conversion from null to the auto-incremented value.
As jeet mentioned you can provide nullColumnHack as a second parameter. And as you yourself mentioned autoincrement isn't necessary to increment a value of primary key.
So the syntax:
insert into rule (_id) values(null)
where _id is primary key and autoincremented value is correct for sql. I think most SQL databases will replace null with new incremented value, at least MySQL, SQLite and Oracle can do this
Thus:
ContentValues cv = new ContentValues();
db.insert("rule", "_id", cv);
should give you desired results.
You need to add autoincrement to your create table query like:
"create table rule (_id integer primary key autoincrement);";
In your case you need to manually set the ID of the row with each insert. this way it will increment it automatically when you insert an empty row as you did in your case.
Try this way :
ContentValues initialValues= new ContentValues();
if(check here --id is null----)
{
initialValues.put("_id", "0");
}
else
{
initialValues.put("_id", id);
}
mDb.insert(TABLE, null, initialValues)
Check following:
http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#insert(java.lang.String, java.lang.String, android.content.ContentValues)
SQL doesn't allow inserting a completely empty row without naming at least one column name. If your provided values is empty, no column names are known and an empty row can't be inserted. If not set to null, the nullColumnHack parameter provides the name of nullable column name to explicitly insert a NULL into in the case where your values is empty.
the insert needs a null value you just have to put
db.insert ("people", null, c);
Related
I need to retrieve the id of the row inserted just now. ie, i have a table for words and a table for meaning. i need the wordId of the word i insert in the table for words and that wordId is used for inserting the meaning in meaning table. Can anyone help me out??
I thought i could use trigger and tried the trigger:
"CREATE TRIGGER IF NOT EXISTS word_insert_trigger AFTER INSERT ON tb_words BEGIN select NEW.word_id from tb_words; END;"
like this. i tried this in sqlite dbbrowser. but it didn't work out.
i need the row id when i insert a row like this :"insert into tb_words(word_name) values('test');"
How can i do that without using "SELECT last_insert_rowid()"? like in the following link:
How to retrieve the last autoincremented ID from a SQLite table?
No need for a trigger. Use the SQliteDatabase insert method. It returns the id (as a long) (more correctly it returns the rowid and assuming that the word_id column has been defined as an alias of the rowid column, then the returned value will be the value assigned to the word_id column).
An alias of the rowid column is defined if word_id INTEGER PRIMARY KEY is coded (the AUTOINCREMENT key may be used BUT in generally should not be used).
You may wish to read SQLite AUTOINCREMENT and/or Rowid Tables
Instead of something like :-
db.execsql("insert into tb_words(word_name) values('test');");
You would use something like :-
ContentValues cv = new ContentValues();
cv.put("word_name","test");
long word_id = db.insert("tb_words",null,cv);
1.which data type should be used to store data like group=AB+ ?
E/SQLiteLog: (1) near "group": syntax error SQLiteDatabase:
Error inserting
district=jhapa phone=9843284985 name=Tom group=AB+
My table is in this format
CREATE TABLE IF NOT EXISTS `Doners` (\n" +
"\t`name`\tTEXT,\n" +
"\t`phone`\tNUMERIC,\n" +
"\t`group`\tBLOB,\n" +
"\t`district`\tTEXT\n" +
");";
For Android you can either use
- native SQL via the SQLiteDatabase execSQL method
- the SQLiteDatabase convenience insert family of methods :-
insert (effectively INSERT OR IGNORE)
insertOrThrow (standard INSERT)
insertWithOnConflict
SQLiteDatabase - insert
So assuming that you want to insert :-
Tom into the name column,
9843284985 into the phone column,
AB+ into the group column,
NOTE that group is an SQLite keyword and therefore cannot be used and will result in a syntax error, unless it is enclosed SQL As Understood By SQLite - SQLite Keywords
jhapa
And that the variable db is an instantiated instance of the SQliteDatabase class then :-
you could use :-
db.execSQl("INSERT INTO `Doners` VALUES('Tom',9843284985,'AB+','jhapa')");
noting that a value must be provided for all the defined columns and that the values should be in the order that the columns were defined in.
or you could use :-
db.execSQL("INSERT INTO Doners (district,phone,name,`group`) VALUES ('jhapa','9843284985','Tom','AB+')");
Here you specify the columns into which the values will be placed, you can specify them in what order you like (values will be inserted according to the order), you can also omit columns (dependant upon the column definition)
Defining a column as NOT NULL would require a column and value. However, if a DEFAULT value has been defined as well as NOT NULL then the column can be omitted.
you could use the insert convenience method like :-
ContentValues cv = new ContentValues();
cv.put("phone","9843284985");
cv.put("name","Tom);
cv.put("`group`","AB+");
cv.put("district","jhapa");
long rowid = db.insert("Doners",null,cv);
rowid will be the rowid of the inserted row (a unique identifier of the row) or if no row was inserted then -1.
the convenience method :-
it builds the SQL on your behalf
protects against SQL injection
encloses values accordingly
suitable encodes byte[]'s into the the x'ff00fe.......' used by SQL.
returns the rowid (executes a query using last_insert_rowid()).
in regards to :-
which data type should be used to store data like group=AB+ ?
Due to SQLite's flexibility it probably does not matter what type is assigned to the column. That is with the exception of the rowid or an alias of the rowid (the_column INTEGER PRIMARY KEY makes the_column an alias of the rowid column) any type of data can be stored in any type of column and to further expand on the flexibility type can be virtually anything (keywords and other syntactically confusing values excepted).
As such CREATE TABLE mytable (mycolumn RUMPLESTILTSKIN) is valid (column has numeric affinity). see - Datatypes In SQLite Version 3
I am creating a table using the following query:
private static final String SQL_CREATE_ENTRIES = "CREATE TABLE person_info ( uniqueId INTEGER,first_name TEXT,last_name TEXT,
address TEXT)";
sqLiteDatabase.execSQL(SQL_CREATE_ENTRIES);
I am inserting the values as follows:
// Create a new map of values, where column names are the keys
ContentValues values = new ContentValues();
values.put("first_name", "Anshul");
values.put("last_name", "Jain");
values.put("address", "Bangalore");
return db.insert(TABLE_NAME, null, values);
Note that I am not giving any value for uniqueId column. Thus, uniqueId column values are null.
When I query the database and try to the type of each column using cursor.getType(i), it returns Cursor.FIELD_TYPE_NULL for uniqueId column. According to the documentation, if all the column values are null, then it will return this value. But ideally it should return Cursor.FIELD_TYPE_INTEGER because that's what I declared while creating the database.
Is there any other way of retrieving the correct column type when all the values of a column are null.
Most SQL database engines (every SQL database engine other than
SQLite, as far as we know) uses static, rigid typing. With static
typing, the datatype of a value is determined by its container - the
particular column in which the value is stored.
SQLite uses a more general dynamic type system. In SQLite, the
datatype of a value is associated with the value itself, not with its
container.
SQLite Docs
This behavior of returning Cursor.FIELD_TYPE_NULL(which according to you is not ideal) is absolutely ideal because SQLite is designed in that way only.
Querying the database to get the type of a Container using cursor.getType(i) will only work if the Container is not NULL otherwise it returns Cursor.FIELD_TYPE_NULL (as in your case).
You can use PRAGMA table_info(table_name) for retrieving the datatype.
Check this SO answer -- Getting the type of a column in SQLite
I have the below method which inserts values in my sqlite db. I'm trying to update the code to handle situations where "carid" and "sellerno" already exist in the table and if they do to replace with the new values being inserted. Any help is appreciated.
public void addListItem(String carid,String sellerno,String condition,String dat) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(carid, carid);
values.put(sellerno, sellerno);
values.put(cond, condition);
values.put(updatetime, dat);
db.insert(TABLE_CARS, null, values);
db.close();
}
There are two requirements:
SQLite needs to know that the combination of carid and sellerno must be unique for all rows in the table.
SQLite needs to know what to do when an insert or update results in a conflict (more than one row with the same combination of values for those columns).
You can do both of these at once by modifying your CREATE TABLE command as follows:
CREATE TABLE tableName (
column1 ...,
column2 ...,
...,
UNIQUE(column1, column2) ON CONFLICT REPLACE)
Now any insert/update will automatically replace the values in existing rows when the insert/update would create a conflict.
However, there may be situations where you do NOT want to replace the values in the row when there is a conflict. In those cases, you should specify the conflict algorithm in the insert/update itself (using this or this), which will override the replace algorithm specified above. Alternatively, you can leave off the ON CONFLICT REPLACE above and just use regular inserts/updates, but then you must insert/update with conflict when you want to replace.
You can read more about conflict algorithms here.
The update code is very similar to what you have now.
You have to add the new values but the same ids that you want, and then instead of the method insert(...) you use replace(...) or update(...).
db.update(TABLE_CARS, values, "_id "+"="+1, null);
// The third argument above is the where clause.
The other way would be:
db.replace(TABLE_CARS, null, values);
The rest of your code is the same. Just change the insert line.
this is the code where I am trying to insert into my table and getting an exception that column ShopName(COL_SN) is not unique though I am giving a name that is not already existing in the database.That particular column is the primary key of the table
public void insert(String sn,String skn,String sa,String un,String pwd) throws SQLiteConstraintException
{
sdb=this.getWritableDatabase();
System.out.println("in insert method");
//sdb.execSQL("insert into " + TABLE_ShopDetails + " values(" +sn+ "," +skn+ "," +sa+ "," +un+ "," +pwd+ ")");
ContentValues cv=new ContentValues();
cv.put(COL_SN,sn);
cv.put(COL_SKN,skn);
cv.put(COL_SA,sa);
cv.put(COL_UN,un);
cv.put(COL_PWD,pwd);
sdb.insert(TABLE_ShopDetails,COL_SN,cv);
sdb.insert(TABLE_ShopDetails,COL_SKN,cv);
sdb.insert(TABLE_ShopDetails,COL_SA,cv);
sdb.insert(TABLE_ShopDetails,COL_UN,cv);
sdb.insert(TABLE_ShopDetails,COL_PWD,cv);
}
just call insert only once
sdb.insert(TABLE_ShopDetails,null,cv);
You should call insert() only once.
The ContentValues object already contains the values for all columns. By inserting multiple times, you're trying to create duplicate records, which results in a primary key violation.
The second parameter can be null, it's only for special cases (when values is empty).
You definitely only need to call insert once as others have said. The second optional parameter should most likely be null, it is for the following ...
optional; may be null. SQL doesn't allow inserting a completely empty row without naming at least one column name. If your provided values is empty, no column names are known and an empty row can't be inserted. If not set to null, the nullColumnHack parameter provides the name of nullable column name to explicitly insert a NULL into in the case where your values is empty.
Also you might want to look into setting up a content provider. The link below would serve as a great tutorial.
Android SQLite database and content provider - Tutorial