iOS Development learning Note-Data Persistence database (Sqlite.swift)

Data Persistence SQLite database (Sqlite.swift use )

First, introduction

SQLite is a lightweight embedded database, it occupies a very low resource, in the embedded device, may only need hundreds of K of memory is sufficient. Its processing speed is faster than the two famous databases of MySQL and PostgreSQL. SQLite provides some C function interfaces that you can use to manipulate the database. By using these interfaces to pass some standard SQL statements (in char * types) to the SQLite function, SQLite will manipulate the database for you

A table in a database is a file that is typically placed in a sandbox document directory with a file suffix of db (database)

Sqlite.swift: He's the third-party library for Swift's professional-built, SQLite-based Swift package, GitHub address: Https://github.com/stephencelis/SQLite.swift

Second, the use of Sqlite.swift

The first thing is to import the Sqlite.swift library (import method self-Baidu), import the response of the binary file, but also import the database sqlite[focus], the settings after the completion of the interface should be like the Red line part

Using Sqlite.swift basic Features

: Playground-noun:a place where people can play//use SQLite before you remember to add the project properties build phases option, add SQLite iOS to target Dependencies In//used to introduce the basic use of Sqlite.swift address https://github.com/stephencelis/SQLite.swift//detailed use address: https://github.com/stephencelis /sqlite.swift/blob/master/documentation/index.md#sqliteswift-documentationimport sqlite//** link Database Let db = Try Connection ("Path/to/db.sqlite3")//Connect with database (emphasis)//** define table properties let users = Table ("Users")//Create data table name Let ID = expres Sion<int64> ("id")//define table properties Let name = Expression<string?> ("name") Let email = expression<string> ("email")//** Build Table Try Db.run (users.create {T in//CREATE table only needs to be generated once, multiple runs will error T.column (ID, primarykey:true) t.col Umn (name) t.column (email, unique:true)})//CREATE TABLE "Users" (//"id" INTEGER PRIMARY KEY not null,//" Name "text,//" email "TEXT not NULL unique//)//* insert Let Insert = Users.insert (name <-" Alice ", email <-" [EMAIL&N Bsp;protected]//insert information let rowID = Try Db.run (insert)//return the inserted ID//execute Insert//INSERT INTO "users" ("name", "email") VALUES (' Alice ', ' [EMAIL&NBSP;PR Otected] ') for the user in try Db.prepare (users) {//is used for cyclic use (. Prepare: Indicates that an action is being prepared to perform a table)//Returns the table row print ("ID: \ ( User[id]), name: \ (User[name]), email: \ (User[email]) ")//Id:1, name:optional (" Alice "), email: [email protected ]}//* Choose//select * from "users" let Alice = users.filter (id = = ROWID)//[filter: Filter]//query (return a table is not a row, cannot output directly) can manipulate it like a data table ( and sync to the initial table) if it fails, the number of tables is 0 (db.scalar (alice.count)//0)//* update try Db.run (alice.update (email <-email.replace ("mac.com  ", with:" me.com "))//Perform update//update" users "SET" email "= replace (" email ", ' mac.com ', ' me.com ')//This is still part of the update//WHERE (" id "= 1)//* Delete try Db.run (Alice.delete ())//delete/delete from "Users" WHERE ("id" = 1) Db.scalar (users.count)//0//"Scalar: Quantity"//Statistics rows//SELECT COUNT (*) from "Users"////recommendations, actually used, will be part of the generation Code (such as a built-in table) to another place, to quantify some other data//SQlite.swift also works as a lightweight, swift-friendly wrapper over the C api.//can execute statements directly???? Let stmt = Try Db.prepare ("INSERT into Users" VALUES (?) ") For mail in ["[Email protected]", "[email protected]"] {try Stmt.run (email)}db.totalchanges//3db.chang ES//1db.lastinsertrowid//3for row in Try Db.prepare ("Select ID, e-mail from users") {print ("ID: \ (row[0]), Email: \ (row[1])//use subscript instead of column//id:optional (2), email:optional ("[email protected]")//Id:optional (3), email: Optional ("[email protected]")}db.scalar ("SELECT count (*) from users")//2

Tips: SQLite database can be opened using visualizer Mesasqlite software

Sqlite.swift's use of GitHub introduction (detail): https://github.com/stephencelis/sqlite.swift/blob/master/documentation/index.md- Sqliteswift-documentation

Extended Links: SQLite common statements

iOS Development learning Note-Data Persistence database (Sqlite.swift)