![]() ![]() This column, or columns, is called the primary key (PK) of the table and enforces the entity integrity of the table. Primary Key ConstraintsĪ table typically has a column or combination of columns that contain values that uniquely identify each row in the table. Primary keys and foreign keys are two types of constraints that can be used to enforce data integrity in SQL Server tables. Import static .SQL Server 2016 (13.x) and later Azure SQL Database Azure SQL Managed Instance Also if you have a result set of only one row and you need to retrieve values of certain columns, you can do it like this: There are also some useful methods to check the position of a cursor: boolean isAfterLast(), isBeforeFirst, isFirst, isLast and isNull(columnIndex). boolean moveToLast(): moves the cursor to the lase row in the result set, returns false if the result set is empty.boolean moveToPrevious(): moves the cursor to the previous row in the result set, returns false if the cursor is past the first row.boolean moveToPosition(int position): moves the cursor to a certain row index within the boolean result set, returns false if the position is un-reachable.boolean moveToFirst(): moves the cursor to the first row in the result set, returns false if the result set is empty.boolean moveToNext(): moves the cursor by one record in the result set, returns false if moved past the last row in the result set.There are some common methods that you will use with cursors: Result sets of queries are returned in Cursor objects. String Order By by: A string Order By by clause.String Having: A string specifying HAVING clause.String Group by: A string specifying group by clause.String selection args: The parameters of the WHERE clause.String WHERE clause: where clause, if none pass null.String columns: The projection of the query, i.e., the columns to retrieve.String Table Name: The name of the table to run the query against.The db.query has the following parameters: Public void onCreate(SQLiteDatabase db) Ĭursor c=db.query(viewEmps, columns, colDeptName+ " =?", Our class will have the following members: onUpgrade(SQLiteDatabse db, int oldVersion, int newVersion): invoked when we make a modification to the database such as altering, dropping, creating new tables.onCreate(SQLiteDatabase db): invoked when the database is created, this is where we can create tables and columns to them, create views or triggers.This class provides two methods to override to deal with the database: The first step is to create a class that inherits from SQLiteOpenHelper class. First, we will create a class that handles all the operations required to deal with the database such as creating the database, creating tables, inserting and deleting records and so on. ViewEmps: to display employees and their relative departments.īy default, SQLite on Android does not have a management interface or an application to create and manage databases from, so we're going to create the database ourselves by code.In this tutorial, we will create a simple database application to store employees data. SQLite Full Unicode support is optional and not installed by default. ![]()
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