Third-party Fmdb of data storage

On Thursday, Friday in the busy company's things and stocks, did not have time to update the blog, this week to fill, learning summary under Fmdb.

Fmdb is a package for sqlite, especially in the case of multithreading, using SQLite is very cumbersome, while using Fmdb is relatively simple, the following is a code example using Fmdatabase and Fmdatabasequeue

viewcontroller.m//fmdbdemo////Created by Cyw on 15-4-26.//Copyright (c) 2015 Cyw. All rights reserved.//#import "ViewController.h" #import "FMDB.h" @interface Viewcontroller () @end @implementation    viewcontroller-(void) viewdidload{[super viewdidload];//Fmdb commonly used three classes://1.FMDatabase: Single SQLite database for executing SQL statements// 2.FMDatabaseQueue: Result set of SQL statements//3.FMRESULTSET:SQL statements executed under multithreading//1. Database file path NSString *path=[nssearchpathfordirectorie    Sindomains (NSDocumentDirectory, Nsuserdomainmask, YES) lastobject];    NSString *filepath=[path stringbyappendingpathcomponent:@ "Cyw.sqlite"];    NSLog (@ "%@", FilePath); Create Fmdb object//parameter has 3 in the case://1. File path file does not exist automatically created//2.nil creates a temporary database in memory and automatically destroys when fmdatabase shuts down//[email protected] "" will create an empty database in the temp directory, destroy when closed//fmdatabase *db=[[fmdatabase alloc]initwithpath:filepath];//fmdatabase *bd=[fmdatabase datab        Asewithpath:filepath]; Open Database//if ([db Open]) {////New database//[self createtable:db];///////Pluginto data//[self insertdata:db];////query data//[self selectdata:db];//[db close];//}//database There are locks and things In Fmdb can be implemented with Fmdatabasequeue//lock mainly solves the problem of multi-threaded transactions is added an implicit lock//CREATE DATABASE queue Fmdatabasequeue *queue=[fmdatabasequeue databas    equeuewithpath:filepath];//[Self queueselect:queue];//[self queuetransaction:queue];        [Self queueintranscation:queue]; }-(BOOL) CreateTable: (fmdatabase*) db{//This two SQL performs an error together//create table if not exists p_class (CId integer primary key, C    Name varchar (20)); NSString *[email protected] "CREATE table if not exists person (ID integer primary key autoincrement, age integer Not n Ull,name text not Null,photo blob,registertime datetime DEFAULT (DateTime (Current_timestamp, ' localtime ')), sex char (1) Default ' 0 ', Money Numeric (10,2), classId integer,constraint fk_person_class foreign Key (classId) references P_class (CId ));";/    /fmdatabase update operations are all using the Executeupdate method query using the ExecuteQuery method BOOL result= [db executeupdate:strsql]; if (reSult) {NSLog (@ "Database creation succeeded");    } else {NSLog (@ "Database creation failed"); } return result;    -(void) InsertData: (fmdatabase*) db{[db executeupdate:@ "delete from person"]; Different parameters of the Executeupdate method//[DB executeupdate:@ "INSERT into P_class (cid,cname) values (?,?);" withargumentsinarray:@[@    1001,@ "Software Engineering"];    Note Add @ [db executeupdate:@ insert INTO person (NAME,AGE,MONEY,CLASSID) values (?,?,?,?); ", @" Cuiyw ", @24,@200.3,@1001]; [DB executeupdatewithformat:@ INSERT INTO person (NAME,AGE,MONEY,CLASSID) VALUES (%@,%d,%f,%d), @ "Cyw", 23,210.9,1001 ];}   -(void) Selectdata: (fmdatabase*) db{//query data nsstring *[email protected] "Select Id,name,age,money from Person";//    Fmresultset return result set Fmresultset *set=[db Executequery:strsql];        while ([Set next]) {int pid=[set intforcolumn:@ "id"];        NSString *name=[set Stringforcolumnindex:1];        int Age=[set intforcolumn:@ "age"];        float Money=[set Doubleforcolumnindex:3]; NSLog (@ "%d%@%d%f", Pid,name,age,moNey);    } nsstring *[email protected] "Select Cid,cname from P_class";    Fmresultset return result set Fmresultset *set1=[db EXECUTEQUERY:STRSQL1];        while ([Set1 next]) {nsstring *name=[set1 stringforcolumnindex:1];        int Age=[set1 intforcolumn:@ "CId"];//float money=[set doubleforcolumnindex:2];    NSLog (@ "%@%d", name,age); }}-(void) Queueselect: (fmdatabasequeue*) queue{//Open Database [queue indatabase:^ (Fmdatabase *db) {[Self selectdata:    DB]; }];} Two ways of writing a transaction-(void) Queuetransaction: (fmdatabasequeue*) queue{[Queue indatabase:^ (Fmdatabase *db) {[Self selectdata        :d b];        [DB BeginTransaction];        [DB executeupdate:@ "update person set money=money+20.0 where id=4"];        [DB executeupdate:@ "update person set money=money-20.0 where id=3"];        [DB commit];    [Self selectdata:db]; }];} -(void) Queueintranscation: (fmdatabasequeue*) queue{[Queue intransaction:^ (Fmdatabase *db, BOOL *rollback) {[sel F SELECTDATA:DB];        [DB executeupdate:@ "update person set money=money+20.0 where id=4"];        [DB executeupdate:@ "update person set money=money-20.0 where id=3"];    [Self selectdata:db]; }];}    -(void) didreceivememorywarning{[Super didreceivememorywarning]; Dispose of any resources the can be recreated.} @end

Third-party Fmdb of data storage