SqlLite 基本操作

1.数据类型

• ●  SQLite将数据划分为以下⼏几种存储类型:

• ●  integer : 整型值

• ●  real : 浮点值

• ●  text : ⽂文本字符串

• ●  blob : ⼆二进制数据(⽐比如⽂文件)

• ●  实际上SQLite是⽆无类型的

• ●  就算声明为integer类型,还是能存储字符串⽂文本(主键除外)

• ●  建表时声明啥类型或者不声明类型都可以,也就意味着创表语句可以这么写:

• create table t_student(name, age);

#import "ViewController.h"

#import <sqlite3.h>

@interface ViewController ()

//1.创建数据库 (保存路径)

@property (nonatomic,assign)sqlite3 *db;

@end

@implementation ViewController

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

//3.增加 数据 (100条 数据随机)

for (int i = 0; i <2; i++) {

NSString *strName = [NSString stringWithFormat:@"8mingyeuxin-%d",i];

NSString *sqlStr = [NSString stringWithFormat:@"INSERT INTO t_student (name ,score)VALUES('%@',%.02f)",strName,arc4random_uniform(1000)/10.0];

//执行

int success =   sqlite3_exec(_db, sqlStr.UTF8String, NULL, NULL, NULL);

if (success == SQLITE_OK) {

NSLog(@"添加成功!");

}else{

NSLog(@"添加失败!");

}

}

}

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

//4.删除 数据 (70 - 80 分数)

NSString *sqlStr = @"DELETE FROM t_student WHERE score > 80.0";

//执行

int success =   sqlite3_exec(_db, sqlStr.UTF8String, NULL, NULL, NULL);

if (success == SQLITE_OK) {

NSLog(@"删除成功!");

}else{

NSLog(@"删除失败!");

}

}

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

//5.修改 数据 (修改分数小于60.0为60.0)

NSString *sqlStr = @"UPDATE t_student SET score = 60.0 WHERE score < 60.0";

//执行

int success = sqlite3_exec(_db, sqlStr.UTF8String, NULL, NULL, NULL);

if (success == SQLITE_OK) {

NSLog(@"修改成功!");

}else{

NSLog(@"修改失败!");

}

}

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

//6.查询数据 ( score >= 60)

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

//查询数据 ( name  中带 8 数字)

NSString *sqlStr = @"SELECT * FROM t_student WHERE name LIKE '%ming%'";

//查询之后  把结果放在 stmt对象

// 保存所有的结果集

sqlite3_stmt *stmt = nil;

sqlite3_prepare_v2(_db, sqlStr.UTF8String, -1, &stmt, NULL);

//获取到所有结果  每一步  查询到一条记录

while (sqlite3_step(stmt) == SQLITE_ROW) {

//取出一条记录

// name TEXT    column

const unsigned char * name =  sqlite3_column_text(stmt, 1);

NSString *strName = [NSString stringWithCString:(const char *)name encoding:NSUTF8StringEncoding];

//score  REAL

double score =  sqlite3_column_double(stmt, 2);

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

}

}

- (void)viewDidLoad {

[super viewDidLoad];

//打开数据库 如果没有就创建

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

NSLog(@"%@",path);

int success =  sqlite3_open(path.UTF8String, &_db);

if (success == SQLITE_OK) {

NSLog(@"创建数据库成功!");

//2.创建表 (指定字段  -> 需求: 保存 学生信息 id  name score)

//用sql语句 来创建

//编写sql语句

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

//执行sql语句

int success_t =  sqlite3_exec(_db, str.UTF8String, NULL, NULL, NULL);

if (success_t == SQLITE_OK) {

NSLog(@"创建表成功!");

}else{

NSLog(@"创建表失败!");

}

}else{

NSLog(@"创建数据库失败!");

}

//关闭数据库

sqlite3_close(_db);

}

@end