使用SQL语句实现1.创建函数fn_getauthor，实现根据书名返回作者；—数据库名：library00

在 library00 数据库中创建函数 fn_getauthor 的 SQL 语句如下：

CREATE FUNCTION fn_getauthor (@bookname VARCHAR(50))
RETURNS VARCHAR(50)
AS
BEGIN
    DECLARE @author VARCHAR(50)
    SELECT @author = author
    FROM books
    WHERE bookname = @bookname
    RETURN @author
END

该函数的作用是根据输入的书名返回该书的作者。在函数中，首先声明了一个变量 @author，然后使用 SELECT 语句从 books 表中查询该书的作者。

使用方法示例：

SELECT dbo.fn_getauthor('The Great Gatsby')

该语句会返回 The Great Gatsby 这本书的作者名字。

相关问题

-- 1.创建函数fn_getauthor，实现根据书名返回作者；——library00 -- 2.创建函数fn_delsell，实现根据bookid删除交易数据；——bookstore -- 3.创建函数`fn_getmoviename`，实现根据演员姓名查找其出演的第一步电影名称；- cinema_db

好的，你的第一个问题是关于创建函数的。那我来回答一下：

1.函数fn_getauthor的实现如下：

CREATE FUNCTION fn_getauthor(book_name VARCHAR(100))
RETURNS VARCHAR(100)
AS 
BEGIN
    DECLARE author_name VARCHAR(100);
    SELECT author INTO author_name FROM library00 WHERE book = book_name;
    RETURN author_name;
END

2.函数fn_delsell的实现如下：

CREATE FUNCTION fn_delsell(book_id INT)
RETURNS INT
AS 
BEGIN
    DELETE FROM bookstore WHERE bookid = book_id;
    RETURN @@ROWCOUNT;
END

3.函数fn_getmoviename的实现如下：

CREATE FUNCTION fn_getmoviename(actor_name VARCHAR(100))
RETURNS VARCHAR(100)
AS 
BEGIN
    DECLARE movie_name VARCHAR(100);
    SELECT TOP 1 movie INTO movie_name FROM cinema_db WHERE actor = actor_name;
    RETURN movie_name;
END

以上三个函数分别实现了根据书名返回作者、根据bookid删除交易数据以及根据演员姓名查找其出演的第一步电影名称。希望能对你有所帮助！

使用sharepreferences 1、创建名诗词数据表，字段主要包括：id、题名、作者姓名、全文。 2、实现添加、查询、修改、删除诗词信息的功能。

以下是使用SharedPreferences实现诗词数据表的示例代码：

1. 创建名诗词数据表，字段主要包括：id、题名、作者姓名、全文。

public class Poem {
    private int id;
    private String title;
    private String author;
    private String content;

    public Poem(int id, String title, String author, String content) {
        this.id = id;
        this.title = title;
        this.author = author;
        this.content = content;
    }

    public int getId() {
        return id;
    }

    public String getTitle() {
        return title;
    }

    public String getAuthor() {
        return author;
    }

    public String getContent() {
        return content;
    }
}

2. 实现添加、查询、修改、删除诗词信息的功能。

public class PoemManager {
    private static final String POEM_PREFS_NAME = "poem_prefs";
    private static final String POEM_KEY_PREFIX = "poem_";

    private Context mContext;
    private SharedPreferences mPrefs;

    public PoemManager(Context context) {
        mContext = context;
        mPrefs = context.getSharedPreferences(POEM_PREFS_NAME, Context.MODE_PRIVATE);
    }

    public void addPoem(Poem poem) {
        SharedPreferences.Editor editor = mPrefs.edit();
        editor.putString(POEM_KEY_PREFIX + poem.getId(), poemToString(poem));
        editor.apply();
    }

    public Poem getPoem(int id) {
        String poemString = mPrefs.getString(POEM_KEY_PREFIX + id, null);
        if (poemString != null) {
            return stringToPoem(poemString);
        }
        return null;
    }

    public void updatePoem(Poem poem) {
        SharedPreferences.Editor editor = mPrefs.edit();
        editor.putString(POEM_KEY_PREFIX + poem.getId(), poemToString(poem));
        editor.apply();
    }

    public void deletePoem(int id) {
        SharedPreferences.Editor editor = mPrefs.edit();
        editor.remove(POEM_KEY_PREFIX + id);
        editor.apply();
    }

    public List<Poem> getAllPoems() {
        List<Poem> poemList = new ArrayList<>();
        Map<String, ?> allEntries = mPrefs.getAll();
        for (Map.Entry<String, ?> entry : allEntries.entrySet()) {
            if (entry.getKey().startsWith(POEM_KEY_PREFIX)) {
                Poem poem = stringToPoem((String) entry.getValue());
                if (poem != null) {
                    poemList.add(poem);
                }
            }
        }
        return poemList;
    }

    private String poemToString(Poem poem) {
        return poem.getId() + "," + poem.getTitle() + "," + poem.getAuthor() + "," + poem.getContent();
    }

    private Poem stringToPoem(String poemString) {
        String[] parts = poemString.split(",");
        if (parts.length == 4) {
            int id = Integer.parseInt(parts[0]);
            String title = parts[1];
            String author = parts[2];
            String content = parts[3];
            return new Poem(id, title, author, content);
        }
        return null;
    }
}

使用示例：

// 创建诗词管理器
PoemManager poemManager = new PoemManager(context);

// 添加诗词
Poem poem = new Poem(1, "静夜思", "李白", "床前明月光，疑是地上霜。举头望明月，低头思故乡。");
poemManager.addPoem(poem);

// 查询诗词
Poem queriedPoem = poemManager.getPoem(1);

// 修改诗词
if (queriedPoem != null) {
    queriedPoem.setTitle("静夜思（改）");
    poemManager.updatePoem(queriedPoem);
}

// 删除诗词
poemManager.deletePoem(1);

// 获取所有诗词
List<Poem> poemList = poemManager.getAllPoems();