SQlite_3

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简单易懂的demo// 1. UserDB.h#import <Foundation/Foundation.h>@interface UserDB : NSObject- (void)createTable;- (void)insertTable;- (void)selectTable;- (void)deleteTable;@end// UserDB.m#import "UserDB.h"#import <sqlite3.h>@implementation UserDB- (void)createTable {        sqlite3 *sqlite = nil;    NSString *filePath = [self localPath];    // 1- 打开数据库    int result =  sqlite3_open([filePath UTF8String], &sqlite);    if (result != SQLITE_OK) {        NSLog(@"打开数据库失败");        return;    }        // 2- 创建表的SQL语句    NSString *sql = @"CREATE TABLE IF NOT EXISTS User (username TEXT primary key,password TEXT,email TEXT)";        // 3- 执行SQL语句    char *error = nil;    result = sqlite3_exec(sqlite, [sql UTF8String], NULL, NULL, &error);    if (result != SQLITE_OK) {        NSLog(@"创建表失败");        return;    }        // 4- 关闭数据库    sqlite3_close(sqlite);    NSLog(@"创建表成功");            }- (void)insertTable {        sqlite3 *sqlite = nil;    NSString *filePath = [self localPath];    // 1- 打开数据库    int result = sqlite3_open([filePath UTF8String], &sqlite);    if (result != SQLITE_OK) {        NSLog(@"打开数据库失败");        return;    }    // 2- 创建数据库语句 (占位)    NSString *sql = @"INSERT INTO User(username,password,email) VALUES (?,?,?)";    // 编译    sqlite3_stmt *stmt = nil;    result = sqlite3_prepare_v2(sqlite, [sql UTF8String], -1, &stmt, NULL);    if (result != SQLITE_OK) {        NSLog(@"准备失败");        return;    }    // 3- 填充和填充数据    NSString *username = @"Charles";    NSString *password = @"123";    NSString *email = @"75517668@qq.com";    sqlite3_bind_text(stmt, 1, [username UTF8String], -1, NULL);    sqlite3_bind_text(stmt, 2, [password UTF8String], -1, NULL);    sqlite3_bind_text(stmt, 3, [email UTF8String], -1, NULL);        // 4- 执行SQL语句    result = sqlite3_step(stmt);    if (result == SQLITE_ERROR || result == SQLITE_MISUSE) {        NSLog(@"执行SQL语句失败");        return;    }    // 5- 关闭数据库句柄 和 关闭数据库    sqlite3_finalize(stmt);    sqlite3_close(sqlite);    NSLog(@"数据插入成功");    }- (void)selectTable {    sqlite3 *sqlite = nil;    NSString *filePath = [self localPath];        // 1- 打开数据库    int result = sqlite3_open([filePath UTF8String], &sqlite);    if (result != SQLITE_OK) {        NSLog(@"数据库打开失败");        return;    }    // 2- 创建SQL语句    NSString *sql = @"select username,password,email from user where username=?";        // 3- 编译 和 绑定    sqlite3_stmt *stmt = nil;    sqlite3_prepare_v2(sqlite, [sql UTF8String], -1, &stmt, NULL);    NSString *username = @"Charles";    sqlite3_bind_text(stmt, 1, [username UTF8String], -1, NULL);        result = sqlite3_step(stmt);        if (result == SQLITE_ERROR || result == SQLITE_MISUSE) {        NSLog(@"执行SQL语句失败");        return ;    }    // 4- 返回遍历的每一行    while (result == SQLITE_ROW) {        char *username = (char *)sqlite3_column_text(stmt, 0);        char *password = (char *)sqlite3_column_text(stmt, 1);        char *email = (char *)sqlite3_column_text(stmt, 2);                NSString *uname = [self encoding:username];        NSString *pword = [self encoding:password];        NSString *mail = [self encoding:email];                NSLog(@"用户名:%@ 密码:%@ 邮箱:%@",uname,pword,mail);        result = sqlite3_step(stmt);    }        // 5- 关闭句柄 和 关闭数据库    sqlite3_finalize(stmt);    sqlite3_close(sqlite);                }- (void)deleteTable {    sqlite3 *sqlite = nil;    // 1- 打开数据库    NSString *filePath = [self localPath];    int result = sqlite3_open([filePath UTF8String], &sqlite);    if (result != SQLITE_OK) {        NSLog(@"打开数据库失败");        return ;    }    // 2-SQL语句    NSString *sql = @"delete from user where username=?";    sqlite3_stmt *stmt = nil;        // 3- 准备和绑定    sqlite3_prepare_v2(sqlite, [sql UTF8String], -1, &stmt, NULL);    NSString *username = @"Charles";    sqlite3_bind_text(stmt, 1, [username UTF8String], -1, NULL);        // 4-执行句柄    result = sqlite3_step(stmt);    if (result == SQLITE_ERROR || result == SQLITE_MISUSE) {        NSLog(@"删除失败");        return ;    }        // 5-关闭句柄 和  关闭数据库    sqlite3_finalize(stmt);    sqlite3_close(sqlite);        }- (NSString *)encoding:(char *)cString {    return [NSString stringWithCString:cString encoding:NSUTF8StringEncoding];}- (NSString *)localPath {            // 创建路径    NSString *filePath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];    filePath = [filePath stringByAppendingPathComponent:@"data.sqlite"];    return filePath;}@end
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