Question

我正在创建一个脚本来从API获取数据并将其保存在Postgresql数据库中。当我尝试使用id选择一个SELECT id FROM (...)并保存到查询中时，它将返回整个SELECT而不是id的值。

count = ("""
        SELECT COUNT(name) 
        FROM cinema 
        WHERE name = %s;
        """,
        (cinema_name)
    )

    if count == 0:
        query = ("""
            INSERT INTO cinema
            VALUES (%s, %s, %s, %s, %s); 
            """
        )
        data = (cinema_id, cinema_name, cinema_is_active, cinema_created_at, cinema_updated_at)
        cur.execute(query, data)
        conn.commit()
        theater_cinema_id = cinema_id
        cinema_id += 1
    else:
        query = ("""
            SELECT id
            FROM cinema
            WHERE name = %s;
            """,
            (cinema_name)
        )
        cinema_id = query
        theater_cinema_id = cinema_id
    #

我希望输出为id，这是我从数据库中选择的整数。但这会返回整个查询。

PostgreSQL日志

2018-12-19 19:26:14.401 UTC [75] ERROR:  column "cinema_id" is of type integer but expression is of type record at character 39
2018-12-19 19:26:14.401 UTC [75] HINT:  You will need to rewrite or cast the expression.
2018-12-19 19:26:14.401 UTC [75] STATEMENT:  
            INSERT INTO theater
            VALUES (5, ('
                SELECT id
                FROM cinema
                WHERE name = %s;
                ', 'Cinemark'), 'Ingresso','4');

Answer 1

在实际填充theater_cinema_id之前，您应该先搜索电影院。

# Query the cinema ID
cur.execute("""
    SELECT id 
    FROM table 
    WHERE name = %s;
    """,
    (cinema_name)
)

cinema = cur.fetchone()

# Checks if a cinema was found
if cinema:
     # Cinema exists
     theater_cinema_id = cinema[0]
else:
   # Otherwise create the cinema
   cur.execute("""
        INSERT INTO cinema
        VALUES (%s, %s, %s, %s, %s)
        """,
        (cinema_id, cinema_name, cinema_is_active, cinema_created_at, cinema_updated_at)
   )
   theater_cinema_id = cinema_id
   cinema_id += 1

# Add any additional inserts / updates then commit towards the end  
conn.commit()

查询= SELECT ID（...）返回整个查询

1 个答案: