对于iOS工程师有一道常考的面试题，即iOS数据存储的方式
标答如下：
Plist（NSArray\NSDictionary）
Preference (偏好设置\NSUserDefaults)
NSCoding(NSKeyed Archiver\NSkeyedUnarchiver)
SQLite3
Core Data
今天就跟大家分享一下，SQLite3的基础知识
什么是SQLite
SQLite 是一款轻型的嵌入式关系型数据库，
它速度要强于Mysql，PostgreSQL，而且占用资源少，在嵌入式设备中可能只需要几百K的内存。
下面是创建该数据库的demo（备注我们需要导入libsqlite3.0.tbd的库）
#import "ViewController.h"
#import <sqlite3.h>
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
NSString *filename=[[NSSearchPathForDirectoriesInDomains(13, 1, 1)lastObject]stringByAppendingPathComponent:@"newsqlite.sqlite"];
// Do any additional setup after loading the view, typically from a nib.
sqlite3 *database=nil;
//打开数据库,如果数据库不存在就创建
if( sqlite3_open(filename.UTF8String,&database)==SQLITE_OK)
{
NSLog(@"打开成功");
/**
* 如果存在就无需创建
*/
char *errmsg;
NSString *sql=@"create table if not exists t_student(id integer primary key autoincrement,name text,age integer);";
sqlite3_exec(database, sql.UTF8String, NULL, NULL, &errmsg);
if(errmsg)
{
NSLog(@"创建表失败");
}else{NSLog(@"创建表成功");
}
/**
* 关闭数据库
*/
sqlite3_close(database);
}
else{
NSLog(@"打开数据库失败");
}
}
@end
为了简便，我们把获取沙盒路径封装的类别里代码如下
NSString+Tool.h
#import <Foundation/Foundation.h>
@interface NSString (Tool)
+(NSString * )cachaPathName:(NSString *)fileName;
@end
NSString+Tool.m
#import "NSString+Tool.h"
@implementation NSString (Tool)
+(NSString * )cachaPathName:(NSString *)fileName{
return [[NSSearchPathForDirectoriesInDomains(13, 1, 1) lastObject] stringByAppendingPathComponent:fileName];
}
@end
然后我们来实现一下，数据库中的增删改查四种操作
用故事板拖四个按钮分别是增删改查，在按钮的方法实现中实现对表的增删改查
#import "ViewController.h"
#import <sqlite3.h>
#import "NSString+Tool.h"
static sqlite3 * dataBase = nil;
@interface ViewController ()
@property (nonatomic ,copy) NSString * filename;
@end
@implementation ViewController
- (IBAction)selectAction:(id)sender {
//1.打开数据库
if (sqlite3_open(self.filename.UTF8String,&dataBase) == SQLITE_OK) {
//2.执行查询语句
//准备查询
NSString * sql = @"select * from t_sss;";
//查询句柄
sqlite3_stmt * stmt;
if (sqlite3_prepare(dataBase, sql.UTF8String, -1, &stmt, NULL) == SQLITE_OK) {
//查询数据
while (sqlite3_step(stmt) == SQLITE_ROW) {
//获取表数据的内容
NSString * name = [NSString stringWithCString:(const char *)sqlite3_column_text(stmt, 1) encoding:NSUTF8StringEncoding];
NSLog(@"name = %@",name);
NSUInteger age = sqlite3_column_int(stmt, 2);
NSLog(@"age = %zd",age);
}
}
//3.关闭数据库
sqlite3_close(dataBase);
}
}
- (IBAction)insertAction:(id)sender {
//1.打开数据库
if (sqlite3_open(self.filename.UTF8String,&dataBase) == SQLITE_OK) {
//2.执行插入语句
for (int i = 0; i < 100; i ++) {
NSString * sql =[NSString stringWithFormat: @"insert into t_sss (name,age) values (‘%@‘,%zd);",@"别昱枢",arc4random_uniform(100)];
char * errmsg;
sqlite3_exec(dataBase, sql.UTF8String, NULL, NULL, &errmsg);
if (errmsg) {
NSLog(@"插入失败");
}else{
NSLog(@"插入成功");
}
//3.关闭数据库
sqlite3_close(dataBase);
}
}
}
- (IBAction)deleteAction:(id)sender {
//1.打开数据库
if (sqlite3_open(self.filename.UTF8String,&dataBase) == SQLITE_OK) {
//2.执行插入语句
for (int i = 0; i < 100; i ++) {
NSString * sql =@"delete from t_sss where name = ‘gaga‘;";
char * errmsg;
sqlite3_exec(dataBase, sql.UTF8String, NULL, NULL, &errmsg);
if (errmsg) {
NSLog(@"删除失败");
}else{
NSLog(@"删除成功");
}
//3.关闭数据库
sqlite3_close(dataBase);
}
}
}
- (IBAction)updateAction:(id)sender {
//1.打开数据库
if (sqlite3_open(self.filename.UTF8String,&dataBase) == SQLITE_OK) {
//2.执行更新语句
for (int i = 0; i < 100; i ++) {
NSString * sql =@"update t_sss set name = ‘gaga‘ where age > 50;";
char * errmsg;
sqlite3_exec(dataBase, sql.UTF8String, NULL, NULL, &errmsg);
if (errmsg) {
NSLog(@"更新失败");
}else{
NSLog(@"更新成功");
}
//3.关闭数据库
sqlite3_close(dataBase);
}
}
}
- (void)viewDidLoad {
[super viewDidLoad];
NSString * filename = [NSString cachaPathName:@"sss.sqlite"];
self.filename = filename;
NSLog(@"%@",filename);
//操作sqlite3
//打开数据库，如果不存在就创建
//arg1:数据库的沙盒存放地址
//arg2:数据库的地址，也可以叫句柄
if (sqlite3_open(filename.UTF8String, &dataBase) == SQLITE_OK)
{
NSLog(@"数据库打开成功");
//建表,如果存在表就不建
NSString * sql = @"create table if not exists t_sss (id integer primary key autoincrement , name text, age integer);";
//执行数据库语句
char * errmsg;
sqlite3_exec(dataBase, sql.UTF8String, NULL, NULL,&errmsg);
if (errmsg) {
NSLog(@"创建表失败");
}else{
NSLog(@"创建表成功");
}
//关闭数据库
sqlite3_close(dataBase);
}else{
NSLog(@"数据库打开失败");
}
}
@end
细心的同学可以看出增删改的操作相似，所以我们封装一下
SqliteManager.h
#import <Foundation/Foundation.h>
@interface SqliteManager : NSObject
+(BOOL) sqlite3WithSql :(NSString *)sql;
@end
SqliteManager.m
#import "SqliteManager.h"
#import "NSString+Tool.h"
#import <sqlite3.h>
static sqlite3 * dataBase = nil;
@interface BYSSqliteManager ()
@property (nonatomic ,copy) NSString * filename;
@end
@implementation BYSSqliteManager
+(BOOL) sqlite3WithSql :(NSString *)sql{
return NO;
}
+(void)initialize{
NSString * filename = [NSString cachaPathName:@"sss.sqlite"];
NSLog(@"%@",filename);
//操作sqlite3
//打开数据库，如果不存在就创建
//arg1:数据库的沙盒存放地址
//arg2:数据库的地址，也可以叫句柄
if (sqlite3_open(filename.UTF8String, &dataBase) == SQLITE_OK)
{
NSLog(@"数据库打开成功");
//建表,如果存在表就不建
NSString * sql = @"create table if not exists t_sss (id integer primary key autoincrement , name text, age integer);";
//执行数据库语句
char * errmsg;
sqlite3_exec(dataBase, sql.UTF8String, NULL, NULL,&errmsg);
if (errmsg) {
NSLog(@"创建表失败");
}else{
NSLog(@"创建表成功");
}
//关闭数据库
sqlite3_close(dataBase);
}else{
NSLog(@"数据库打开失败");
}
}
@end
时间： 2024-10-02 04:42:15