Mysql 将结果集的多行合并为一行_Mysql_Sql_Resultset

Mysql 将结果集的多行合并为一行

mysql sql

Mysql 将结果集的多行合并为一行,mysql,sql,resultset,Mysql,Sql,Resultset,我有这样一个问题： SELECT DISTINCT obl_books.book_id, obl_books.long_title, obl_books.short_title, obl_authors.first_name FROM obl_books, obl_authors, books_authors WHERE obl_books.book_id = b

我有这样一个问题：

SELECT DISTINCT 
        obl_books.book_id,
        obl_books.long_title,
        obl_books.short_title,
        obl_authors.first_name
FROM 
        obl_books,
        obl_authors,
        books_authors
WHERE 
        obl_books.book_id = books_authors.book_id
    AND 
        obl_authors.author_id = books_authors.author_id
    AND 
        obl_books.short_title = 'SQL'

Book1| SQL REFERENCE | author1 | author2 | author3

它为每个作者提供了两个单独的行。我希望它像这样排成一行：

SELECT DISTINCT 
        obl_books.book_id,
        obl_books.long_title,
        obl_books.short_title,
        obl_authors.first_name
FROM 
        obl_books,
        obl_authors,
        books_authors
WHERE 
        obl_books.book_id = books_authors.book_id
    AND 
        obl_authors.author_id = books_authors.author_id
    AND 
        obl_books.short_title = 'SQL'

Book1| SQL REFERENCE | author1 | author2 | author3

如何直接在SQL查询中或通过对ResultSet result执行某些操作来实现它？好心的导游。请告诉我没有任何PLSQL机制。

取决于哪个rdbms，但您可以尝试

SELECT DISTINCT obl_books.book_id||obl_books.long_title|| etc...

或者在帮助中查找“Concat（）”

取决于哪个rdbms，但您可以尝试

SELECT DISTINCT obl_books.book_id||obl_books.long_title|| etc...

或者在帮助中查找“Concat（）”如果您使用的是MySQL，请尝试以下操作：

SELECT DISTINCT 
        obl_books.book_id,
        obl_books.long_title,
        obl_books.short_title,
        GROUP_CONCAT(obl_authors.first_name, ',')
ETC...

如果您使用的是MySQL，请将分隔符（逗号）更改为您想要的任何分隔符

SELECT DISTINCT 
        obl_books.book_id,
        obl_books.long_title,
        obl_books.short_title,
        GROUP_CONCAT(obl_authors.first_name, ',')
ETC...

根据需要更改分隔符（逗号）

使用
```
JOIN
```
代替旧的SQL-89隐式JOIN
```
WHERE
```
语法
删除
```
DISTINCT
```
添加
```
分组依据
```

用于连接一列中的所有名称：

SELECT 
        b.book_id,
        b.long_title,
        b.short_title,
        GROUP_CONCAT(a.first_name
                     ORDER BY a.first_name
                     SEPARATOR ', '
                    ) AS first_names
FROM 
        obl_books AS b
    JOIN
        books_authors AS ba
            ON  b.book_id = ba.book_id
    JOIN
        obl_authors AS a
            ON  a.author_id = ba.author_id
WHERE 
        b.short_title = 'SQL' 
GROUP BY
        b.book_id,
        b.long_title,
        b.short_title ;

使用
```
JOIN
```
代替旧的SQL-89隐式JOIN
```
WHERE
```
语法
删除
```
DISTINCT
```
添加
```
分组依据
```

用于连接一列中的所有名称：

SELECT 
        b.book_id,
        b.long_title,
        b.short_title,
        GROUP_CONCAT(a.first_name
                     ORDER BY a.first_name
                     SEPARATOR ', '
                    ) AS first_names
FROM 
        obl_books AS b
    JOIN
        books_authors AS ba
            ON  b.book_id = ba.book_id
    JOIN
        obl_authors AS a
            ON  a.author_id = ba.author_id
WHERE 
        b.short_title = 'SQL' 
GROUP BY
        b.book_id,
        b.long_title,
        b.short_title ;