I have an application with some searching, where I have a number of search terms.
I would like to do something like.
for( each_search_term ) {
INSERT INTO tmpTable SELECT dataId FROM SearchTable WHERE _id = ?;
}
I wasn't sure if the supported way is like the code below, or if there is some other better supported method.
void doInsert( SqliteDatabase db, long dataId ) {
db.execSQL( "INSERT INTO tmpTable SELECT dataId FROM SearchTable WHERE _id = ?;", new String [] { String.valueOf( dataId ) } );
}
The developer documents seem to imply that execSQL is not for INSERT operations.
Execute a single SQL statement that is NOT a SELECT/INSERT/UPDATE/DELETE.
You can try something like:
INSERT INTO table2 (column1, column2, column3, ...)
SELECT column1, column2, column3, ...
FROM table1;........................
Use this with
db.exeSQL(command);
Related
Say I have ProductVersion Table:
CREATE TABLE ProductVersion
(
Id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
PrvVersionName NOT NULL
);
And I have this code to do INSERT on this table:
SQLiteDatabase database = this.getWritableDatabase();
String sql = "INSERT INTO ProductVersion (PrvVersionName) VALUES (?);";
SQLiteStatement s = database.compileStatement(sql);
s.bindString(1, data.getVersionName());
long id = s.executeInsert();
s.close();
My question, is the value returned from s.executeInsert() same as if I query using "SELECT last_insert_rowid();" after doing this INSERT?
executeInsert() will return the ID of the row inserted
FROM DOCS
SQLiteStatement.executeInsert ()
Execute this SQL statement and return the ID of the row inserted due to this call. The SQL statement should be an INSERT for this to be a useful call.
The documentation for SQLiteStatement#executeInsert seems to confirm this:
Execute this SQL statement and return the ID of the row inserted due to this call. The SQL statement should be an INSERT for this to be a useful call.
I need to make a column equal to another column in the table. I can't figure it out using the update method of my SQLiteDatabase.
I know the SQL statement is:
UPDATE coolTable SET columnA = columnB;
Do I put it in the ContentValues I pass the function? or the selection string?
You can use update() only to set literal values (as bind params), not any other kind of expression supported by sqlite SQL syntax.
Use execSQL() to execute your raw UPDATE query with column name expression.
execSQL() with error checking:
SQLiteDatabase db = getReadableDatabase();
try {
long count = DatabaseUtils.queryNumEntries(db, "pweb");
db.execSQL("update pweb set h_id = _id;");
long rows = DatabaseUtils.longForQuery(db, "SELECT changes()", null);
if(count != rows ) Log.e("wrong count","update failed");
}
catch(SQLException e){
Log.e("SQLException","update failed");
}
db.close();
but I was wondering if it is possible to use the database's update()
function instead of execSQL()
You can use sqlite3 to view and manipulate you data, and test out sql commands.
Create a table:
CREATE TABLE pweb (_id INTEGER PRIMARY KEY,h_id INTEGER ,sent INTEGER);
See the original rows:
sqlite> select * from pweb;
1|10|1
2|20|1
3|30|0
4|40|0
execute a column update:
sqlite> update pweb set h_id = _id;
See the changes to all rows:
sqlite> select * from pweb;
1|1|1
2|2|1
3|3|0
4|4|0
Something more complex ?
sqlite> update pweb set h_id = _id + 1;
result:
sqlite> select * from pweb;
1|2|1
2|3|1
3|4|0
4|5|0
See also Understanding SQLITE DataBase in Android:
I have a query that joins 2 tables get the required data on my android, what picture here is the user clicks on an item and the item's ID is used to query the right data in the Database, I know I can simply use database.query() but it according to my research it is used for simply database querying only, in my case I should use rawQuery() which provides more power of the database. below is my query which links table 1 to table 2 to get the users name from table one and user last name from table 2 if the foreign key is the same as user key
Assume this is my query:
String sQuery = SELECT table1.ID, table2.userlastname FROM table1, table2 WHERE "+table1.ID = table2.foreign;
If i try to specify the user id like below it gets all data in the database table which means i should replace id with "=?" but how do I do this when I am dealing which such a query, one that uses db.rawQuery() instead of db.query()
`private Object userInfo(int id)
{
String sQuery = SELECT table1.ID, table2.userlastname
FROM table1, table2 WHERE "+table1.ID = id;
}`
Basically you replace the parameter by question marks '?' and pass them through a String array in the order they appear in the query.
String queryStr = "SELECT table1.ID, table2.userlastname
FROM table1
INNER JOIN table2 ON table1.ID = table2.foreign;
WHERE table1.ID = ?";
String[] args = new String[1];
args[0] = String.valueOf(id);
Cursor cur = db.rawQuery(queryStr, args);
it did not work until I joined table 2 like:
`String queryStr = "SELECT table1.ID, table2.userlastname
FROM table1
INNER JOIN table2 ON table1.ID = table2.foreign
WHERE table1.ID = ?";
String[] args = new String[1];
args[0] = String.valueOf(id);
Cursor cur = db.rawQuery(queryStr, args);`
Pretend I have a table with 2 columns. _id and name. _id is the primary key and I do not want to set this value manually. I want to perform an insert of name="john," and let the program create my own _id. I am unclear what "index" to use when inserting and how many question marks to use. Does this code do the job? Should the index for john be 1 or 2?
String TABLENAME = "table";
SQLiteStatement statement = db.compileStatement("INSERT INTO "+TABLENAME+" VALUES(?);");
statement.bindString(1,"john");
statement.executeInsert();
Next, say I want to manually set my own _id value. Would I change the code to:
String TABLENAME = "table";
SQLiteStatement statement = db.compileStatement("INSERT INTO "+TABLENAME+" VALUES(?,?);");
statement.bindLong(1,666); //Manual _id.
statement.bindString(2,"john");
statement.executeInsert();
Your first example where you provide only the name will not work:
sqlite> create table test (i integer primary key autoincrement, j text);
sqlite> insert into test values ('asd');
Error: table test has 2 columns but 1 values were supplied
sqlite> insert into test values (null, 'asd');
sqlite> select * from test;
1|asd
sqlite> insert into test (j) values ('asd');
sqlite> select * from test;
1|asd
2|asd
so you need to identify the name column as the destination of the sole value this way, (or as you mentioned in your comment pass null):
SQLiteStatement statement = db.compileStatement("INSERT INTO "+TABLENAME+" (name) VALUES(?);");
Your second example should work fine.
This would apply to some table created this way:
create table SomeTable (_id integer primary key autoincrement, name text)
Then
SQLiteStatement statement = db.compileStatement("INSERT INTO "+TABLENAME+" VALUES(null,?);");
statement.bindString(1,"john");
Should also work.
How do I use prepared statements in SQlite in Android?
For prepared SQLite statements in Android there is SQLiteStatement. Prepared statements help you speed up performance (especially for statements that need to be executed multiple times) and also help avoid against injection attacks. See this article for a general discussion on prepared statements.
SQLiteStatement is meant to be used with SQL statements that do not return multiple values. (That means you wouldn't use them for most queries.) Below are some examples:
Create a table
String sql = "CREATE TABLE table_name (column_1 INTEGER PRIMARY KEY, column_2 TEXT)";
SQLiteStatement stmt = db.compileStatement(sql);
stmt.execute();
The execute() method does not return a value so it is appropriate to use with CREATE and DROP but not intended to be used with SELECT, INSERT, DELETE, and UPDATE because these return values. (But see this question.)
Insert values
String sql = "INSERT INTO table_name (column_1, column_2) VALUES (57, 'hello')";
SQLiteStatement statement = db.compileStatement(sql);
long rowId = statement.executeInsert();
Note that the executeInsert() method is used rather than execute(). Of course, you wouldn't want to always enter the same things in every row. For that you can use bindings.
String sql = "INSERT INTO table_name (column_1, column_2) VALUES (?, ?)";
SQLiteStatement statement = db.compileStatement(sql);
int intValue = 57;
String stringValue = "hello";
statement.bindLong(1, intValue); // 1-based: matches first '?' in sql string
statement.bindString(2, stringValue); // matches second '?' in sql string
long rowId = statement.executeInsert();
Usually you use prepared statements when you want to quickly repeat something (like an INSERT) many times. The prepared statement makes it so that the SQL statement doesn't have to be parsed and compiled every time. You can speed things up even more by using transactions. This allows all the changes to be applied at once. Here is an example:
String stringValue = "hello";
try {
db.beginTransaction();
String sql = "INSERT INTO table_name (column_1, column_2) VALUES (?, ?)";
SQLiteStatement statement = db.compileStatement(sql);
for (int i = 0; i < 1000; i++) {
statement.clearBindings();
statement.bindLong(1, i);
statement.bindString(2, stringValue + i);
statement.executeInsert();
}
db.setTransactionSuccessful(); // This commits the transaction if there were no exceptions
} catch (Exception e) {
Log.w("Exception:", e);
} finally {
db.endTransaction();
}
Check out these links for some more good info on transactions and speeding up database inserts.
Atomic Commit In SQLite (Great in depth explanation, go to Part 3)
Database transactions
Android SQLite bulk insert and update example
Android SQLite Transaction Example with INSERT Prepared Statement
Turbocharge your SQLite inserts on Android
https://stackoverflow.com/a/8163179/3681880
Update rows
This is a basic example. You can also apply the concepts from the section above.
String sql = "UPDATE table_name SET column_2=? WHERE column_1=?";
SQLiteStatement statement = db.compileStatement(sql);
int id = 7;
String stringValue = "hi there";
statement.bindString(1, stringValue);
statement.bindLong(2, id);
int numberOfRowsAffected = statement.executeUpdateDelete();
Delete rows
The executeUpdateDelete() method can also be used for DELETE statements and was introduced in API 11. See this Q&A.
Here is an example.
try {
db.beginTransaction();
String sql = "DELETE FROM " + table_name +
" WHERE " + column_1 + " = ?";
SQLiteStatement statement = db.compileStatement(sql);
for (Long id : words) {
statement.clearBindings();
statement.bindLong(1, id);
statement.executeUpdateDelete();
}
db.setTransactionSuccessful();
} catch (SQLException e) {
Log.w("Exception:", e);
} finally {
db.endTransaction();
}
Query
Normally when you run a query, you want to get a cursor back with lots of rows. That's not what SQLiteStatement is for, though. You don't run a query with it unless you only need a simple result, like the number of rows in the database, which you can do with simpleQueryForLong()
String sql = "SELECT COUNT(*) FROM table_name";
SQLiteStatement statement = db.compileStatement(sql);
long result = statement.simpleQueryForLong();
Usually you will run the query() method of SQLiteDatabase to get a cursor.
SQLiteDatabase db = dbHelper.getReadableDatabase();
String table = "table_name";
String[] columnsToReturn = { "column_1", "column_2" };
String selection = "column_1 =?";
String[] selectionArgs = { someValue }; // matched to "?" in selection
Cursor dbCursor = db.query(table, columnsToReturn, selection, selectionArgs, null, null, null);
See this answer for better details about queries.
I use prepared statements in Android all the time, it's quite simple:
SQLiteDatabase db = dbHelper.getWritableDatabase();
SQLiteStatement stmt = db.compileStatement("INSERT INTO Country (code) VALUES (?)");
stmt.bindString(1, "US");
stmt.executeInsert();
If you want a cursor on return, then you might consider something like this:
SQLiteDatabase db = dbHelper.getWritableDatabase();
public Cursor fetchByCountryCode(String strCountryCode)
{
/**
* SELECT * FROM Country
* WHERE code = US
*/
return cursor = db.query(true,
"Country", /**< Table name. */
null, /**< All the fields that you want the
cursor to contain; null means all.*/
"code=?", /**< WHERE statement without the WHERE clause. */
new String[] { strCountryCode }, /**< Selection arguments. */
null, null, null, null);
}
/** Fill a cursor with the results. */
Cursor c = fetchByCountryCode("US");
/** Retrieve data from the fields. */
String strCountryCode = c.getString(cursor.getColumnIndex("code"));
/** Assuming that you have a field/column with the name "country_name" */
String strCountryName = c.getString(cursor.getColumnIndex("country_name"));
See this snippet Genscripts in case you want a more complete one. Note that this is a parameterized SQL query, so in essence, it's a prepared statement.
jasonhudgins example won't work. You can't execute a query with stmt.execute() and get a value (or a Cursor) back.
You can only precompile statements that either returns no rows at all (such as an insert, or create table statement) or a single row and column, (and use simpleQueryForLong() or simpleQueryForString()).
To get a cursor, you can't use a compiledStatement. However, if you want to use a full prepared SQL statement, I recommend an adaptation of jbaez's method... Using db.rawQuery() instead of db.query().