李洪强iOS开发之FMDB线程安全的用法

//

//  ViewController.m

//  04 - FMDB线程安全的用法

//

//  Created by 李洪强 on 2017/6/6.

//  Copyright © 2017年 李洪强. All rights reserved.

//

#import "ViewController.h"

//导入头文件

#import "FMDB.h"

@interface ViewController ()

@property(nonatomic,strong)FMDatabaseQueue *dataBaseQ;

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject]stringByAppendingPathComponent:@"student"];

FMDatabaseQueue *dataBaseQ = [FMDatabaseQueue databaseQueueWithPath:path];

_dataBaseQ = dataBaseQ;

[_dataBaseQ inDatabase:^(FMDatabase * _Nonnull db) {

BOOL success = [db open];

if(success){

NSLog(@"创建数据库成功");

//创建表

NSString *str = @"CREATE TABLE IF NOT EXISTS t_student (id INTEGER PRIMARY KEY AUTOINCREMENT ,name TEXT NOT NULL,score REAL NOT NULL)";

if([db executeUpdate:str]){

NSLog(@"创建表成功!");

}else{

NSLog(@"创建表失败!");

}

}else{

NSLog(@"创建数据库失败");

}

}];

}

//增加数据

- (IBAction)insertData:(UIButton *)sender {

[_dataBaseQ inDatabase:^(FMDatabase * _Nonnull db) {

for(int i = 0; i < 100 ; i++){

NSString *strName = [NSString stringWithFormat:@"ming-yuexing-%d",i];

NSString *sqlStr = [NSString stringWithFormat:@"INSERT INTO t_student (name , score) VALUES ('%@',%.2f)",strName,arc4random_uniform(1000)/10.0];

BOOL success = [db executeUpdate:sqlStr];

if(success){

NSLog(@"添加成功");

}else{

NSLog(@"添加失败");

}

}

}];

}

- (IBAction)selectData:(UIButton *)sender {

[_dataBaseQ inDatabase:^(FMDatabase * _Nonnull db) {

NSString *sqlStr = @"SELECT * FROM t_student WHERE score > 60.0 ORDER BY score DESC";

//执行查询语句

FMResultSet *set = [db executeQuery:sqlStr];

while ([set next]) {

NSString *name = [set stringForColumn:@"name"];

CGFloat score = [set doubleForColumn:@"score"];

NSLog(@"name = %@ score = %f",name,score);

}

}];

}

/*

使用FMDB比sql的好处:

线程安全

公共资源在A使用的时候,B不能修改

*/

@end