Flat Files val sharedPreferences =

context.getSharedPreferences(

"user123" , MODE_PRIVATE )

sharedPreferences.edit () .putString( "title" , "Shrek" ) .putInt( "year" , 2001 ) .putFloat( "rating" , 10.0f ) .apply()

sharedPreferences.edit () .putInt( "volume" , 8 ) .apply() < map

< string name= "title"

Shrek</ string

< int name= "year" value= "2001" /> < float name= "rating" value= "10.0" />

< int name= "volume" value= "8" /> </ map

Flat Files val sharedPreferences =

context.getSharedPreferences(

"user123" , MODE_PRIVATE )

sharedPreferences.edit () .putString( "title" , "Shrek" ) .putInt( "year" , 2001 ) .putFloat( "rating" , 10.0f ) .apply()

sharedPreferences.edit () .putInt( "volume" , 8 ) .apply() < map

< string name= "title"

Shrek</ string

< int name= "year" value= "2001" /> < float name= "rating" value= "10.0" />

< int name= "volume" value= "8" /> </ map

Flat Files val sharedPreferences =

context.getSharedPreferences(

"user123" , MODE_PRIVATE )

sharedPreferences.edit () .putString( "title" , "Shrek" ) .putInt( "year" , 2001 ) .putFloat( "rating" , 10.0f ) .apply()

sharedPreferences.edit () .putInt( "volume" , 8 ) .apply() < map

< string name= "title"

Shrek</ string

< int name= "year" value= "2001" /> < float name= "rating" value= "10.0" />

< int name= "volume" value= "8" /> </ map

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} Data Manipulation

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} Data Manipulation

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation

friendship

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation

friendship FROM

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation FROM friendship

friend1

MY_ID

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation FROM friendship

friend1

= MY_ID WHERE

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation FROM friendship

friend1

= :my_id WHERE

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation FROM friendship

WHERE friend1

= :my_id

friend2

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation

friend2 FROM friendship

WHERE friend1

= :my_id SELECT

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation SELECT friend2 FROM friendship

WHERE friend1

= :my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation SELECT friend2 FROM friendship

WHERE friend1

= :my_id

friendship

friend2

MY_ID

            friend1

:my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation SELECT friend2 FROM friendship

WHERE friend1

= :my_id

friendship FROM

friend2

MY_ID

            friend1

:my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation SELECT friend2 FROM friendship

WHERE friend1

= :my_id FROM friendship

  friend2

= :my_id WHERE friend1

MY_ID

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation SELECT friend2 FROM friendship

WHERE friend1

= :my_id friend1 FROM friendship

WHERE friend2

= :my_id SELECT

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation SELECT friend2 FROM friendship

WHERE friend1

= :my_id SELECT

friend1 FROM friendship

WHERE friend2

= :my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation SELECT friend2 FROM friendship

WHERE friend1

= :my_id +

SELECT

friend1 FROM friendship

WHERE friend2

= :my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

  .size()

} X Data Manipulation SELECT friend2 FROM friendship

WHERE friend1

= :my_id UNION

SELECT

friend1 FROM friendship

WHERE friend2

= :my_id

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

var friends = friendships . filter { it . friend1

MY_ID }

. map { it . friend2 }

friends += friendships . filter { it . friend2

MY_ID }

. map { it . friend1 }

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X SELECT friend2

FROM friendship WHERE friend1 = :my_id UNION SELECT friend1

FROM friendship WHERE friend2 = :my_id Data Manipulation

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X SELECT friend2

FROM friendship WHERE friend1 = :my_id UNION SELECT friend1

FROM friendship WHERE friend2 = :my_id Data Manipulation

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friendships: Collection<Friendship>

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X SELECT friend2

FROM friendship WHERE friend1 = :my_id UNION SELECT friend1

FROM friendship WHERE friend2 = :my_id Data Manipulation

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X SELECT friend2

FROM friendship WHERE friend1 = :my_id UNION SELECT friend1

FROM friendship WHERE friend2 = :my_id Data Manipulation

Friendship

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X SELECT friend2

FROM friendship WHERE friend1 = :my_id UNION SELECT friend1

FROM friendship WHERE friend2 = :my_id Data Manipulation

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X SELECT friend2

FROM friendship WHERE friend1 = :my_id UNION SELECT friend1

FROM friendship WHERE friend2 = :my_id Data Manipulation

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X Data Manipulation

user_ checkin SELECT friend2

FROM friendship WHERE friend1 = :my_id UNION SELECT friend1

FROM friendship WHERE friend2 = :my_id

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X Data Manipulation FROM user_checkin SELECT friend2

FROM friendship WHERE friend1 = :my_id UNION SELECT friend1

FROM friendship WHERE friend2 = :my_id

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X Data Manipulation FROM user_checkin SELECT friend2

FROM friendship WHERE friend1 = :my_id UNION SELECT friend1

FROM friendship WHERE friend2 = :my_id

IN

user_id in friends

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X Data Manipulation FROM user_checkin WHERE user_id IN (

SELECT friend2

FROM friendship

WHERE friend1 = :my_id

UNION

SELECT friend1

FROM friendship

WHERE friend2 = :my_id

) Y in f

r

i

e

n

d

s

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X Data Manipulation FROM user_checkin WHERE user_id IN (

SELECT friend2

FROM friendship

WHERE friend1 = :my_id

UNION

SELECT friend1

FROM friendship

WHERE friend2 = :my_id

) Y in

checkin_id

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X Data Manipulation checkin_id

FROM user_checkin WHERE user_id IN (

SELECT friend2

FROM friendship

WHERE friend1 = :my_id

UNION

SELECT friend1

FROM friendship

WHERE friend2 = :my_id

) Y in SELECT

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X Data Manipulation SELECT checkin_id

FROM user_checkin WHERE user_id IN (

SELECT friend2

FROM friendship

WHERE friend1 = :my_id

UNION

SELECT friend1

FROM friendship

WHERE friend2 = :my_id

) Y in

distinct

DISTINCTP

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X Data Manipulation SELECT DISTINCT P checkin_id

FROM user_checkin WHERE user_id IN (

SELECT friend2

FROM friendship

WHERE friend1 = :my_id

UNION

SELECT friend1

FROM friendship

WHERE friend2 = :my_id

) Y in

distinct

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X Data Manipulation SELECT DISTINCT P checkin_id

FROM user_checkin WHERE user_id IN (

SELECT friend2

FROM friendship

WHERE friend1 = :my_id

UNION

SELECT friend1

FROM friendship

WHERE friend2 = :my_id

) Y in size

count

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X Data Manipulation SELECT

count( DISTINCT P checkin_id ) FROM user_checkin WHERE user_id IN (

SELECT friend2

FROM friendship

WHERE friend1 = :my_id

UNION

SELECT friend1

FROM friendship

WHERE friend2 = :my_id

) Y in size

my_id

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

return checkins . filter { it . user_id in friends }

. map { it . checkin_id }

. distinct ()

.size()

} X Data Manipulation SELECT

count( DISTINCT P checkin_id ) FROM user_checkin WHERE user_id IN (

SELECT friend2

FROM friendship

WHERE friend1 = :my_id

UNION

SELECT friend1

FROM friendship

WHERE friend2 = :my_id

) Y in size

fun friendsCheckins(

checkins: Collection<UserCheckin>, 
friends: Collection<Long

): Long {

} X Data Manipulation SELECT

count( DISTINCT P checkin_id ) FROM user_checkin WHERE user_id IN (

SELECT friend2

FROM friendship

WHERE friend1 = :my_id

UNION

SELECT friend1

FROM friendship

WHERE friend2 = :my_id

) Y in size

SQLite and Android class MyDatabase(context: Context, name: String?)

: SQLiteOpenHelper(context, name,

null , VERSION ) {

companion object {

private const val VERSION

1

} Y

} Z

SQLite and Android class MyDatabase(context: Context, name: String?)

: SQLiteOpenHelper(context, name,

null , VERSION ) {

override fun onUpgrade(db: SQLiteDatabase, old: Int, new : Int) { } X

companion object {

private const val VERSION

1

} Y

} Z

SQLite and Android class MyDatabase(context: Context, name: String?)

: SQLiteOpenHelper(context, name,

null , VERSION ) {

override fun onCreate(db: SQLiteDatabase) { } W

override fun onUpgrade(db: SQLiteDatabase, old: Int, new : Int) { } X

companion object {

private const val VERSION

1

} Y

} Z

SQLite and Android class MyDatabase(context: Context, name: String?)

: SQLiteOpenHelper(context, name,

null , VERSION ) {

override fun onCreate(db: SQLiteDatabase) {

db.execSQL(

""" CREATE TABLE user ( _id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL ); """ . trimIndent ())

} W

override fun onUpgrade(db: SQLiteDatabase, old: Int, new : Int) { } X

companion object {

private const val VERSION

1

} Y

} Z

SQLite and Android class MyDatabase(context: Context, name: String?)

: SQLiteOpenHelper(context, name,

null , VERSION ) {

override fun onCreate(db: SQLiteDatabase) {

db.execSQL(

""" CREATE TABLE user ( Z

_id

INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL ); """ . trimIndent ())

} W

override fun onUpgrade(db: SQLiteDatabase, old: Int, new : Int) { } X

companion object {

private const val VERSION

1

} Y

} Z object UserColumns {

const val TABLE_NAME

"user"

const val ID

"_id"

const val NAME

"name" } A

SQLite and Android class MyDatabase(context: Context, name: String?)

: SQLiteOpenHelper(context, name,

null , VERSION ) {

override fun onCreate(db: SQLiteDatabase) {

db.execSQL(

""" CREATE TABLE ${ UserColumns. TABLE_NAME } ( Z

${ UserColumns. ID } INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,

${ UserColumns. NAME } TEXT NOT NULL ); """ . trimIndent ())

} W

override fun onUpgrade(db: SQLiteDatabase, old: Int, new : Int) { } X

companion object {

private const val VERSION

1

} Y

} Z object UserColumns {

const val TABLE_NAME

"user"

const val ID

"_id"

const val NAME

"name" } A user

_id

name

SQLite and Android class MyDatabase(context: Context, name: String?)

: SQLiteOpenHelper(context, name,

null , VERSION ) {

override fun onCreate(db: SQLiteDatabase) {

db.execSQL(

""" CREATE TABLE ${ UserColumns. TABLE_NAME } ( Z

${ UserColumns. ID } INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,

${ UserColumns. NAME } TEXT NOT NULL ); """ . trimIndent ())

} W

override fun onUpgrade(db: SQLiteDatabase, old: Int, new : Int) { } X

companion object {

private const val VERSION

1

} Y

} Z object UserColumns {

const val TABLE_NAME

"user"

const val ID

"_id"

const val NAME

"name" } A object FriendshipColumns {

const val TABLE_NAME

"friendship"

const val FRIEND_1

"friend1"

const val FRIEND_2

"friend2"

const val BECAME_FRIENDS

"became_friends" } B

SQLite and Android class MyDatabase(context: Context, name: String?)

: SQLiteOpenHelper(context, name,

null , VERSION ) {

override fun onCreate(db: SQLiteDatabase) {

db.execSQL(

""" CREATE TABLE ${ UserColumns. TABLE_NAME } ( Z

${ UserColumns. ID } INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,

${ UserColumns. NAME } TEXT NOT NULL ); """ . trimIndent ())

db.execSQL(

""" CREATE TABLE ${ FriendshipColumns. TABLE_NAME } (

${ FriendshipColumns. FRIEND_1 } INTEGER NOT NULL REFERENCES ${ UserColumns. TABLE_NAME } ,

${ FriendshipColumns. FRIEND_2 } INTEGER NOT NULL REFERENCES ${ UserColumns. TABLE_NAME } ,

${ FriendshipColumns. BECAME_FRIENDS } INTEGER NOT NULL DEFAULT CURRENT_TIME, PRIMARY KEY ( ${ FriendshipColumns. FRIEND_1 } , ${ FriendshipColumns. FRIEND_2 } ) ); """ . trimIndent ())

} W

override fun onUpgrade(db: SQLiteDatabase, old: Int, new : Int) { } X

companion object {

private const val VERSION

1

} Y

} Z object UserColumns {

const val TABLE_NAME

"user"

const val ID

"_id"

const val NAME

"name" } A object FriendshipColumns {

const val TABLE_NAME

"friendship"

const val FRIEND_1

"friend1"

const val FRIEND_2

"friend2"

const val BECAME_FRIENDS

"became_friends" } B

SQLite and Android class MyDatabase(context: Context, name: String?)

: SQLiteOpenHelper(context, name,

null , VERSION ) {

override fun onCreate(db: SQLiteDatabase) {

db.execSQL(

""" CREATE TABLE ${ UserColumns. TABLE_NAME } ( Z

${ UserColumns. ID } INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,

${ UserColumns. NAME } TEXT NOT NULL ); """ . trimIndent ())

db.execSQL(

""" CREATE TABLE ${ FriendshipColumns. TABLE_NAME } (

${ FriendshipColumns. FRIEND_1 } INTEGER NOT NULL REFERENCES ${ UserColumns. TABLE_NAME } ,

${ FriendshipColumns. FRIEND_2 } INTEGER NOT NULL REFERENCES ${ UserColumns. TABLE_NAME } ,

${ FriendshipColumns. BECAME_FRIENDS } INTEGER NOT NULL DEFAULT CURRENT_TIME, PRIMARY KEY ( ${ FriendshipColumns. FRIEND_1 } , ${ FriendshipColumns. FRIEND_2 } ) ); """ . trimIndent ())

} W

override fun onUpgrade(db: SQLiteDatabase, old: Int, new : Int) { } X

companion object {

private const val VERSION

1

} Y

} Z object UserColumns {

const val TABLE_NAME

"user"

const val ID

"_id"

const val NAME

"name" } A object FriendshipColumns {

const val TABLE_NAME

"friendship"

const val FRIEND_1

"friend1"

const val FRIEND_2

"friend2"

const val BECAME_FRIENDS

"became_friends" } B   object CheckinColumns {

const val TABLE_NAME

"checkin"

const val ID

"_id"

const val NAME

"name"

const val TIME

"time" } C

SQLite and Android class MyDatabase(context: Context, name: String?)

: SQLiteOpenHelper(context, name,

null , VERSION ) {

override fun onCreate(db: SQLiteDatabase) {

db.execSQL(

""" CREATE TABLE ${ UserColumns. TABLE_NAME } ( Z

${ UserColumns. ID } INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,

${ UserColumns. NAME } TEXT NOT NULL ); """ . trimIndent ())

db.execSQL(

""" CREATE TABLE ${ FriendshipColumns. TABLE_NAME } (

${ FriendshipColumns. FRIEND_1 } INTEGER NOT NULL REFERENCES ${ UserColumns. TABLE_NAME } ,

${ FriendshipColumns. FRIEND_2 } INTEGER NOT NULL REFERENCES ${ UserColumns. TABLE_NAME } ,

${ FriendshipColumns. BECAME_FRIENDS } INTEGER NOT NULL DEFAULT CURRENT_TIME, PRIMARY KEY ( ${ FriendshipColumns. FRIEND_1 } , ${ FriendshipColumns. FRIEND_2 } ) ); """ . trimIndent ())

db.execSQL(

""" CREATE TABLE ${ CheckinColumns. TABLE_NAME } (

${ CheckinColumns. ID } INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,

${ CheckinColumns. NAME } TEXT NOT NULL,

${ CheckinColumns. TIME } INTEGER NOT NULL ); """ . trimIndent ())

} W

override fun onUpgrade(db: SQLiteDatabase, old: Int, new : Int) { } X

companion object {

private const val VERSION

1

} Y

} Z object UserColumns {

const val TABLE_NAME

"user"

const val ID

"_id"

const val NAME

"name" } A object FriendshipColumns {

const val TABLE_NAME

"friendship"

const val FRIEND_1

"friend1"

const val FRIEND_2

"friend2"

const val BECAME_FRIENDS

"became_friends" } B   object CheckinColumns {

const val TABLE_NAME

"checkin"

const val ID

"_id"

const val NAME

"name"

const val TIME

"time" } C

SQLite and Android class MyDatabase(context: Context, name: String?)

: SQLiteOpenHelper(context, name,

null , VERSION ) {

override fun onCreate(db: SQLiteDatabase) {

db.execSQL(

""" CREATE TABLE ${ UserColumns. TABLE_NAME } ( Z

${ UserColumns. ID } INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,

${ UserColumns. NAME } TEXT NOT NULL ); """ . trimIndent ())

db.execSQL(

""" CREATE TABLE ${ FriendshipColumns. TABLE_NAME } (

${ FriendshipColumns. FRIEND_1 } INTEGER NOT NULL REFERENCES ${ UserColumns. TABLE_NAME } ,

${ FriendshipColumns. FRIEND_2 } INTEGER NOT NULL REFERENCES ${ UserColumns. TABLE_NAME } ,

${ FriendshipColumns. BECAME_FRIENDS } INTEGER NOT NULL DEFAULT CURRENT_TIME, PRIMARY KEY ( ${ FriendshipColumns. FRIEND_1 } , ${ FriendshipColumns. FRIEND_2 } ) ); """ . trimIndent ())

db.execSQL(

""" CREATE TABLE ${ CheckinColumns. TABLE_NAME } (

${ CheckinColumns. ID } INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,

${ CheckinColumns. NAME } TEXT NOT NULL,

${ CheckinColumns. TIME } INTEGER NOT NULL ); """ . trimIndent ())

} W

override fun onUpgrade(db: SQLiteDatabase, old: Int, new : Int) { } X

companion object {

private const val VERSION

1

} Y

} Z object UserColumns {

const val TABLE_NAME

"user"

const val ID

"_id"

const val NAME

"name" } A object FriendshipColumns {

const val TABLE_NAME

"friendship"

const val FRIEND_1

"friend1"

const val FRIEND_2

"friend2"

const val BECAME_FRIENDS

"became_friends" } B   object CheckinColumns {

const val TABLE_NAME

"checkin"

const val ID

"_id"

const val NAME

"name"

const val TIME

"time" } C object UserCheckinColumns {

const val TABLE_NAME

"user_checkin"

const val CHECKIN_ID

"checkin_id"

const val USER_ID

"user_id" } D

SQLite and Android class MyDatabase(context: Context, name: String?) : SQLiteOpenHelper(context, name, null , VERSION ) {

override fun onCreate(db: SQLiteDatabase) { db.execSQL( """ CREATE TABLE ${ UserColumns. TABLE_NAME } (

${ UserColumns. ID } INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,

${ UserColumns. NAME } TEXT NOT NULL ); """ . trimIndent ()) db.execSQL( """ CREATE TABLE ${ FriendshipColumns. TABLE_NAME } (

${ FriendshipColumns. FRIEND_1 } INTEGER NOT NULL REFERENCES ${ UserColumns. TABLE_NAME } ,

${ FriendshipColumns. FRIEND_2 } INTEGER NOT NULL REFERENCES ${ UserColumns. TABLE_NAME } ,

${ FriendshipColumns. BECAME_FRIENDS } INTEGER NOT NULL DEFAULT CURRENT_TIME, PRIMARY KEY ( ${ FriendshipColumns. FRIEND_1 } , ${ FriendshipColumns. FRIEND_2 } ) ); """ . trimIndent ()) db.execSQL( """ CREATE TABLE ${ CheckinColumns. TABLE_NAME } (

${ CheckinColumns. ID } INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,

${ CheckinColumns. NAME } TEXT NOT NULL,

${ CheckinColumns. TIME } INTEGER NOT NULL ); """ . trimIndent ()) db.execSQL( """ CREATE TABLE ${ UserCheckinColumns. TABLE_NAME } (

${ UserCheckinColumns. CHECKIN_ID } INTEGER NOT NULL REFERENCES ${ CheckinColumns. TABLE_NAME } ,

${ UserCheckinColumns. USER_ID } INTEGER NOT NULL REFERENCES ${ UserColumns. TABLE_NAME } , PRIMARY KEY( ${ UserCheckinColumns. CHECKIN_ID } , ${ UserCheckinColumns. USER_ID } ) ); """ . trimIndent ()) } W

override fun onUpgrade(db: SQLiteDatabase, old: Int, new : Int) { } X

companion object {

private const val VERSION

1

} Y

} Z object UserColumns {

const val TABLE_NAME

"user"

const val ID

"_id"

const val NAME

"name" } A object FriendshipColumns {

const val TABLE_NAME

"friendship"

const val FRIEND_1

"friend1"

const val FRIEND_2

"friend2"

const val BECAME_FRIENDS

"became_friends" } B   object CheckinColumns {

const val TABLE_NAME

"checkin"

const val ID

"_id"

const val NAME

"name"

const val TIME

"time" } C object UserCheckinColumns {

const val TABLE_NAME

"user_checkin"

const val CHECKIN_ID

"checkin_id"

const val USER_ID

"user_id" } D

SQLite and Android fun friendsCheckins(db: SQLiteDatabase, myId: Int): Int { A

val cursor = db.rawQuery( """ SELECT count(DISTINCT ${ UserCheckinColumns. CHECKIN_ID } ) FROM ${ UserCheckinColumns. TABLE_NAME } WHERE ${ UserCheckinColumns. USER_ID } IN ( SELECT ${ FriendshipColumns. FRIEND_2 } FROM ${ FriendshipColumns. TABLE_NAME } WHERE ${ FriendshipColumns. FRIEND_1 } = ?1 UNION SELECT ${ FriendshipColumns. FRIEND_1 } FROM ${ FriendshipColumns. TABLE_NAME } WHERE ${ FriendshipColumns. FRIEND_2 } = ?1 ) B

""" . trimIndent (), arrayOf (myId.toString()))

cursor. use {

if ( it .moveToNext()) {

return it .getInt( 0 ) G

J

throw IllegalStateException( "Query returned zero rows" )

} K

} Z

SQLite and Android fun friendsCheckins(db: SQLiteDatabase, myId: Int): Int { A

val

count = "checkin_count"

val cursor = db.rawQuery( """ SELECT count(DISTINCT ${ UserCheckinColumns. CHECKIN_ID } ) AS $ count

FROM

${ UserCheckinColumns. TABLE_NAME } WHERE ${ UserCheckinColumns. USER_ID } IN ( SELECT ${ FriendshipColumns. FRIEND_2 } FROM ${ FriendshipColumns. TABLE_NAME } WHERE ${ FriendshipColumns. FRIEND_1 } = ?1 UNION SELECT ${ FriendshipColumns. FRIEND_1 } FROM ${ FriendshipColumns. TABLE_NAME } WHERE ${ FriendshipColumns. FRIEND_2 } = ?1 ) B

""" . trimIndent (), arrayOf (myId.toString()))

cursor. use {

if ( it .moveToNext()) {

return it .getInt( it .getColumnIndex(count)) G

J

throw IllegalStateException( "Query returned zero rows" )

} K

} Z

SQLite and Android fun friendsCheckins(db: SQLiteDatabase, myId: Int): Int { A

val

count = "checkin_count"

val cursor = db.rawQuery( """ SELECT count(DISTINCT ${ UserCheckinColumns. CHECKIN_ID } ) AS $ count

FROM

${ UserCheckinColumns. TABLE_NAME } WHERE ${ UserCheckinColumns. USER_ID } IN ( SELECT ${ FriendshipColumns. FRIEND_2 } FROM ${ FriendshipColumns. TABLE_NAME } WHERE ${ FriendshipColumns. FRIEND_1 } = ?1 UNION SELECT ${ FriendshipColumns. FRIEND_1 } FROM ${ FriendshipColumns. TABLE_NAME } WHERE ${ FriendshipColumns. FRIEND_2 } = ?1 ) B

""" . trimIndent (), arrayOf (myId.toString()))

cursor. use {

if ( it .moveToNext()) {

return it .getInt( it .getColumnIndex(count)) G

J

throw IllegalStateException( "Query returned zero rows" )

} K

} Z

SQLDelight db . createQuery (TodoItem. FACTORY .titleAndCount( listId )) .mapToOne(TitleAndCount. MAPPER ::map) .observeOn(AndroidSchedulers.mainThread()) .subscribe {

TODO ()

} X

public static final RowMapper<TodoItem> MAPPER

TodoItem.

FACTORY .titleAndCountMapper( CREATOR );

Not type safe db . createQuery (TodoItem. FACTORY .titleAndCount( listId ))

// Wreak havoc 
.mapToOne(TitleAndCount.

MAPPER ::map) .observeOn(AndroidSchedulers.mainThread()) .subscribe {

TODO ()

} X

SQLDelight

db . createQuery (TodoItem. FACTORY .titleAndCount( listId )) .mapToOne(TitleAndCount. MAPPER ::map) .observeOn(AndroidSchedulers.mainThread()) .subscribe {

TODO ()

} X

public static final RowMapper<TodoItem> MAPPER

TodoItem.

FACTORY .titleAndCountMapper( CREATOR ); SQLDelight pre-1.0 .observe()

SQLDelight 1.0 db .titleAndCount( listId ).observe()   .mapToOne()

.observeOn(AndroidSchedulers.mainThread()) 
.subscribe

{

TODO ()

} X

public static final RowMapper<TodoItem> MAPPER = TodoItem. FACTORY .titleAndCountMapper( CREATOR );

SQLDelight 1.0 db .titleAndCount(::CustomType, listId ).observe()   .mapToOne()

.observeOn(AndroidSchedulers.mainThread()) 
.subscribe

{

TODO ()

} X

fun <T> titleAndCount( mapper: (title: String, count: Int) -> T, listId: Long ): Query<T>