IOS 开发学习33 使用sqlite3

Posted 2020-09-30 clnchanpin

sqlite3 命令行简单使用

sqlite3 路径 //打开数据库路径连接
select * from sqlite_master where type=”table”; //显示全部表结构
select * from testable; //显示某张表数据
.tables //查看表
.help //查看帮助
.quit //退出

xcode使用sqlite3步骤

1.加入libsqlite3.dylib

2.头文件

//
//  DbUtils.h
//  smart
//
//  Created by 谢厂节 on 15/5/12.
//  Copyright (c) 2015年 WHR. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "sqlite3.h"

@interface DbUtils : NSObject
{
    sqlite3 *db; //声明一个sqlite3数据库
}
- (NSString *)filePath;//数据库文件的路径。一般在沙箱的Documents里边操作
-(void)openDB;
-(void)closeDB;
-(NSMutableArray *)getAllTypes;
@end

.m文件

//
//  DbUtils.m
//  smart
//
//  Created by 谢厂节 on 15/5/12.
//  Copyright (c) 2015年 WHR. All rights reserved.
//

#import "DbUtils.h"
#import "KMTypes.h"
#import "KMContents.h"

@implementation DbUtils

//打开数据库的方法

- (void)openDB{
       ///文件是否存在
    NSFileManager* fileManager = [NSFileManager defaultManager];
    NSString *dbpath=[self filePath];
    NSLog(@"database path:%@",dbpath);
    BOOL success = [fileManager fileExistsAtPath:dbpath];
    if (!success) {
        NSString *resourcePath=[[NSBundle mainBundle]resourcePath];
        //自己主动复制
        NSString *sourceDBPath=[resourcePath stringByAppendingPathComponent:@"app.bundle/datas.sqlite"];

        NSError *error;
        success = [fileManager copyItemAtPath:sourceDBPath toPath:dbpath error:&error];
        if(!success)
            NSAssert1(0,@"数据库附加失败。‘%@‘.", [error localizedDescription]);
        else
            NSLog(@"数据库附加成功:%@",dbpath);
    }
    if (sqlite3_open([[self filePath] UTF8String], &db) != SQLITE_OK) {
        sqlite3_close(db);
        NSAssert(0, @"数据库打开失败。");
    }
}
- (void)closeDB{
    sqlite3_close(db);
}
//该方法用于返回数据库在Documents目录中的全路径信息
- (NSString *)filePath{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDir = [paths objectAtIndex:0];
    return [documentsDir stringByAppendingPathComponent:@"datas.sqlite"];
}
////查询数据全部类别
- (NSMutableArray *)getAllTypes{
    [self openDB];
    NSMutableArray *array=[NSMutableArray arrayWithCapacity:6 ];

    NSString *sql = @"SELECT * FROM km_types";
    sqlite3_stmt *statement;

    if (sqlite3_prepare_v2(db, [sql UTF8String], -1, &statement, nil) == SQLITE_OK) {
        while (sqlite3_step(statement) == SQLITE_ROW) {
            KMTypes* k= [[KMTypes alloc]init];
            int type_id = (int)sqlite3_column_int(statement,0);
            int parent_id = (int)sqlite3_column_int(statement,1);
            char *type_title = (char *)sqlite3_column_text(statement, 2);
            int type_order = (int)sqlite3_column_int(statement,3);
            int topic_count=(int)sqlite3_column_int(statement,4);

            NSString *type_titleStr = [[NSString alloc] initWithUTF8String:type_title];
            k.type_title = type_titleStr;
            k.type_id=type_id;
            k.parent_id = parent_id;
            k.type_order = type_order;
            k.topic_count=topic_count;

            [array addObject:k];

        }
        sqlite3_finalize(statement);
    }
    [self closeDB];
    return array;
}

@end

这里仅仅实现一个简单的查询功能。