SqlLite 基本操作
1.数据类型
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● SQLite将数据划分为以下⼏几种存储类型:
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● integer : 整型值
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● real : 浮点值
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● text : ⽂文本字符串
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● blob : ⼆二进制数据(⽐比如⽂文件)
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● 实际上SQLite是⽆无类型的
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● 就算声明为integer类型,还是能存储字符串⽂文本(主键除外)
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● 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