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面试题：Objective-C在iOS数据存储中如何实现SQLite数据库的增删改查

请简述在Objective-C项目中，连接SQLite数据库并执行插入一条新记录、删除指定记录、更新指定记录以及查询所有记录操作的步骤和关键代码。
16.4万 热度难度
编程语言Objective-C

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面试题答案

一键面试

连接SQLite数据库

  1. 引入SQLite库：在项目中引入SQLite库，通常是libsqlite3.dylib。
  2. 导入头文件：在需要操作数据库的文件中导入sqlite3.h头文件。
  3. 打开数据库：
sqlite3 *database;
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
NSString *databasePath = [documentsPath stringByAppendingPathComponent:@"yourDatabaseName.db"];
if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) {
    NSLog(@"成功打开数据库");
} else {
    NSLog(@"无法打开数据库: %s", sqlite3_errmsg(database));
}

插入一条新记录

  1. 构建SQL语句：
NSString *insertSQL = @"INSERT INTO yourTableName (column1, column2) VALUES (?,?)";
sqlite3_stmt *statement;
if (sqlite3_prepare_v2(database, [insertSQL UTF8String], -1, &statement, NULL) == SQLITE_OK) {
    // 绑定参数
    sqlite3_bind_text(statement, 1, [value1 UTF8String], -1, SQLITE_TRANSIENT);
    sqlite3_bind_text(statement, 2, [value2 UTF8String], -1, SQLITE_TRANSIENT);
    
    // 执行插入
    if (sqlite3_step(statement) != SQLITE_DONE) {
        NSLog(@"插入失败: %s", sqlite3_errmsg(database));
    }
    sqlite3_finalize(statement);
} else {
    NSLog(@"准备插入语句失败: %s", sqlite3_errmsg(database));
}

删除指定记录

  1. 构建SQL语句：
NSString *deleteSQL = @"DELETE FROM yourTableName WHERE someColumn =?";
sqlite3_stmt *statement;
if (sqlite3_prepare_v2(database, [deleteSQL UTF8String], -1, &statement, NULL) == SQLITE_OK) {
    // 绑定参数
    sqlite3_bind_text(statement, 1, [specificValue UTF8String], -1, SQLITE_TRANSIENT);
    
    // 执行删除
    if (sqlite3_step(statement) != SQLITE_DONE) {
        NSLog(@"删除失败: %s", sqlite3_errmsg(database));
    }
    sqlite3_finalize(statement);
} else {
    NSLog(@"准备删除语句失败: %s", sqlite3_errmsg(database));
}

更新指定记录

  1. 构建SQL语句：
NSString *updateSQL = @"UPDATE yourTableName SET column1 =? WHERE someColumn =?";
sqlite3_stmt *statement;
if (sqlite3_prepare_v2(database, [updateSQL UTF8String], -1, &statement, NULL) == SQLITE_OK) {
    // 绑定参数
    sqlite3_bind_text(statement, 1, [newValue UTF8String], -1, SQLITE_TRANSIENT);
    sqlite3_bind_text(statement, 2, [specificValue UTF8String], -1, SQLITE_TRANSIENT);
    
    // 执行更新
    if (sqlite3_step(statement) != SQLITE_DONE) {
        NSLog(@"更新失败: %s", sqlite3_errmsg(database));
    }
    sqlite3_finalize(statement);
} else {
    NSLog(@"准备更新语句失败: %s", sqlite3_errmsg(database));
}

查询所有记录

  1. 构建SQL语句：
NSString *selectSQL = @"SELECT * FROM yourTableName";
sqlite3_stmt *statement;
if (sqlite3_prepare_v2(database, [selectSQL UTF8String], -1, &statement, NULL) == SQLITE_OK) {
    while (sqlite3_step(statement) == SQLITE_ROW) {
        const unsigned char *column1 = sqlite3_column_text(statement, 0);
        const unsigned char *column2 = sqlite3_column_text(statement, 1);
        NSString *value1 = [NSString stringWithUTF8String:(const char *)column1];
        NSString *value2 = [NSString stringWithUTF8String:(const char *)column2];
        NSLog(@"column1: %@, column2: %@", value1, value2);
    }
    sqlite3_finalize(statement);
} else {
    NSLog(@"准备查询语句失败: %s", sqlite3_errmsg(database));
}

关闭数据库

sqlite3_close(database);