sqlite3数据库的基本操作

3.一般把对数据库的操作单独作为一个类，并且该类是一个单例类
.h文件中的代码:
#import <Foundation/Foundation.h>

#import "Student.h"

@interface DBManager : NSObject

//创建一个单例对象

+(instancetype)shareDBManager;

#pragma mark-------------数据库的基本方法

//打开数据库

-(void)openDB;

//关闭数据库

-(void)closeDB;

//创建表

-(void)createTable;

//增

-(void)insertStudent:(Student *)student;

//删：一般不要根据主键删除，应为rowid要根据主键改变

-(void)deleteStudentWithName:(NSString *)name;

//删除17岁以下的学生

-(void)deleteStudentWithAge;

//改：根据姓名修改年龄

-(void)updateStudentAge:(NSInteger)age withName:(NSString *)name;

//查询全部

-(NSArray *)seleteAllStudent;

//根据条件查询

-(NSArray *)selectWithName:(NSString *)name;

.m中的主要代码:
#import "DBManager.h"

#pragma mark-----------导入包

#import <sqlite3.h>

@interface DBManager ()

@property(nonatomic,strong) NSMutableArray *array;

@end

@implementation DBManager

#pragma mark-------------伪单例的静态方法

+(instancetype)shareDBManager

{

static DBManager *dbManager = nil;

#warning 判断条件一般放在前面

if (nil == dbManager) {

dbManager = [[DBManager alloc] init];

}

return dbManager;

}

#pragma mark-------------数据库的基本方法

//创建一个静态指针，表示唯一的

static sqlite3 *db = nil;

//打开数据库

-(void)openDB

{

if (nil != db ) {

return;

}

//创建路径

NSString *path = NSHomeDirectory();

path = [path stringByAppendingPathComponent:@"student.sqlite"];

//打开数据库

-(void)openDB

{

if (nil != db ) {

return;

}

//创建路径

NSString *path = NSHomeDirectory();

path = [path stringByAppendingPathComponent:@"student.sqlite"];

//打开数据库

int result = sqlite3_open([path UTF8String], &db);

// SQLITE_OK:表示的是代码是否执行

if (result == SQLITE_OK) {

NSLog(@"哈哈,打开成功了");

}

else

{

NSLog(@"打开失败了,错误的操作数为%d",result);

}

}

//关闭数据库

-(void)closeDB

{

//调用关闭方法

int result = sqlite3_close(db);

if (result == SQLITE_OK) {

//将数据库置空

db = nil;

NSLog(@"关闭成功");

}

else

{

NSLog(@"关闭失败,错误的操作数为%d",result);

}

}

//创建表

-(void)createTable

{

//准备sql语句

NSString *createString = @"CREATE TABLE if not exists 'student' ('number' INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL UNIQUE, 'name' TEXT NOT NULL, 'age' INTEGER NOT NULL, 'gender' TEXT DEFAULT male)";

//创建表

int result = sqlite3_exec(db,createString.UTF8String,NULL,NULL,NULL);

if (result == SQLITE_OK) {

NSLog(@"创建表成功了");

}

else

{

NSLog(@"创建表失败了，错误操作数为%d",result);

}

}

//增

-(void)insertStudent:(Student *)student

{

//准备

NSString *insertString = [NSString stringWithFormat:@"insert into 'student'(name,age,gender)values('%@','%ld','%@')",student.name,student.age,student.gender];

//执行

int result = sqlite3_exec(db, insertString.UTF8String, NULL, NULL, NULL);

if (result == SQLITE_OK) {

NSLog(@"插入数据成功");

}

else

{

NSLog(@"插入数据失败,错误操作数为%d",result);

}

}

//删

-(void)deleteStudentWithName:(NSString *)name

{

//准备

NSString *deleteString = [NSString stringWithFormat:@"delete from 'student' where name = '%@' ",name ];

int result = sqlite3_exec(db, deleteString.UTF8String, NULL, NULL, NULL);

if (result == SQLITE_OK) {

NSLog(@"删除成功");

}

else

{

NSLog(@"删除失败");

}

}

//删除17岁以下的学生

-(void)deleteStudentWithAge

{

//准备

NSString *deleteStr = [NSString stringWithFormat:@"delete from 'student' where age < 17"];

int result = sqlite3_exec(db, [deleteStr UTF8String], NULL, NULL, NULL);

if (result == SQLITE_OK) {

NSLog(@"小于17岁的删除成功");

}

else

{

NSLog(@"小于17岁的删除失败");

}

}

//改：根据姓名修改年龄

-(void)updateStudentAge:(NSInteger)age withName:(NSString *)name

{

//准备

NSString *updateString = [NSString stringWithFormat:@"update 'student' set age = %ld where name = '%@'",age,name];

//执行

int result = sqlite3_exec(db, [updateString UTF8String], NULL, NULL, NULL);

if (result == SQLITE_OK) {

NSLog(@"修改成功");

}

else

{

NSLog(@"修改失败,错误为%d",result);

}

}

//查

//查找全部的信息

/*-(NSArray *)seleteAllStudent

{

//准备数组

NSMutableArray *array = nil;

//准备伴随指针

sqlite3_stmt *stmt = nil;

//准备sql语句

NSString *selectString = @"select * from student";

//准备执行：-1:读取的长度为最大值

int result = sqlite3_prepare_v2(db, selectString.UTF8String, -1, &stmt, NULL);

if (result == SQLITE_OK) {

//给数组开辟空间

array = [NSMutableArray arrayWithCapacity:20];

while (sqlite3_step(stmt) == SQLITE_ROW) {

//字段位置:number、name、age、gender

Student *student = [[Student alloc] init];

student.number = sqlite3_column_int(stmt, 0);

//根据字段查询的字符串需要强转为const char *类型后，再转化成OC字符串

student.name = [NSString stringWithUTF8String:(const char*)sqlite3_column_text(stmt, 1)];

student.age = sqlite3_column_int(stmt, 2);

student.gender = [NSString stringWithUTF8String:(const char*)sqlite3_column_text(stmt, 3)];

//添加到数组中

[array addObject:student];

}

}

else

{

NSLog(@"查询失败,失败操作是%d",result);

}

//释放伴随指针

sqlite3_finalize(stmt);

return array;

}

*/

-(NSArray *)seleteAllStudent

{

//准备存放数据的数组

NSMutableArray *array = nil;

//准备查询语句

NSString *selectString = @"select * from student";

//准备伴随指针

sqlite3_stmt *stmt = nil;

//执行

//判断sql语句是否正确

int result = sqlite3_prepare_v2(db,selectString.UTF8String , -1, &stmt, NULL);

if (result == SQLITE_OK) {

//为数组开辟空间

array = [NSMutableArray arrayWithCapacity:4];

//循环每一行

while (sqlite3_step(stmt) == SQLITE_ROW) {

//创建一个学生对象

Student *student = [[Student alloc] init];

//根据每个字段给对象赋值

student.number = sqlite3_column_int(stmt, 0);

student.name = [NSString stringWithUTF8String:(const char*)sqlite3_column_text(stmt, 1)];

student.age = sqlite3_column_int(stmt, 2);

student.gender = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 3)];

//将学生对象加入数组中

[array addObject:student];

}

}

else

{

NSLog(@"查找失败，失败的原因是%d",result);

}

//释放伴随指针

sqlite3_finalize(stmt);

return array;

}

//根据条件查询

-(NSArray *)selectWithName:(NSString *)name

{

// 方法一：

// NSString *selectString = [NSString stringWithFormat:@"select * from 'student' where name = '%@'",name];

//方法二:绑定

//查询字符串

NSString *sqlWord = @"select * from student where name = ?";

NSMutableArray *array = nil;

//伴随指针

sqlite3_stmt *stmt = nil;

int result = sqlite3_prepare(db, [sqlWord UTF8String], -1, &stmt, NULL);

if(result == SQLITE_OK)

{

array = [NSMutableArray arrayWithCapacity:4];

//1：是绑定的第几个问号，从1开始

//绑定指针

sqlite3_bind_text(stmt, 1, [name UTF8String], -1, NULL);

while (sqlite3_step(stmt) == SQLITE_ROW) {

Student *student = [Student new];

student.number = sqlite3_column_int64(stmt, 0);

student.name = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 1)];

student.gender = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 2)];

student.age = sqlite3_column_int(stmt, 3);

[array addObject:student];

NSLog(@"查询成功");

}

}

else

{

NSLog(@"查询失败");

}

sqlite3_finalize(stmt);

return array;

}

//懒方法

-(NSMutableArray *)array

{

if (_array == nil) {

_array = [NSMutableArray array];

}

return _array;

}

@end

将图片存储到数库中，要转换成NSData数据类型存储在数据库中，数据库中用blob类型的数据

Model类的属性

@property (nonatomic, strong)NSString *name;

@property (nonatomic, assign)NSInteger age;

@property (nonatomic, strong)NSString *gender;

@property (nonatomic, strong)NSString *phone;

@property (nonatomic, strong)NSString *address;

@property (nonatomic, strong)NSData *photo;

转换为NSData类型

Person *per = [[Person alloc] init];

per.name = @"Joke";

per.age = 20;

per.gender = @"f";

per.phone = @"110";

per.address = @"fff";

per.photo = UIImageJPEGRepresentation([UIImage imageNamed:@"nvshen.png"], 1);

//插入数据

- (void)myInsertPerson:(Person *)person

{

static sqlite3_stmt *stmt=nil;

NSString *insertString = [NSString stringWithFormat:@"insert into 'person' ('name','age','gender','phone','address','photo') values (?,?,?,?,?,?)"];

int result = sqlite3_prepare(db, insertString.UTF8String, -1, &stmt, nil);

if (SQLITE_OK == result) {

sqlite3_bind_text(stmt, 1, person.name.UTF8String, -1, nil);

sqlite3_bind_int64(stmt, 2, person.age);

sqlite3_bind_text(stmt, 3, person.gender.UTF8String, -1, nil);

sqlite3_bind_text(stmt, 4, person.phone.UTF8String, -1, nil);

sqlite3_bind_text(stmt, 5, person.address.UTF8String, -1, nil);

sqlite3_bind_blob(stmt, 6, [person.photo bytes], (int)[person.photo length], nil);

if (SQLITE_DONE == sqlite3_step(stmt)) {

NSLog(@"ok");

}

}

sqlite3_finalize(stmt);

}

查找
读取数据

- (NSArray *)selectData{

NSMutableArray *array = [NSMutableArray array];

NSString *selectString = @"SELECT * FROM 'STUDENT'";

sqlite3_stmt *stmt = nil;

//

int result = sqlite3_prepare(db, selectString.UTF8String, -1, &stmt, NULL);

if (result == SQLITE_OK) {

while (sqlite3_step(stmt) == SQLITE_ROW) {

NSMutableDictionary *dict = [NSMutableDictionary dictionary];

dict[@"name"] = [NSString stringWithUTF8String:(const char *)sqlite3_column_text(stmt, 0)];

//读取blob数据

(Byte) *data = (Byte *)sqlite3_column_blob(stmt, 1);

int size = sqlite3_column_bytes(stmt, 1);

//转换为NSData

NSData *imageData = [NSData dataWithBytes:data length:size];

dict[@"image"] = imageData;

[array addObject:dict];

}

}

sqlite3_finalize(stmt);

return array;

}