如何使用SQLite批量插入？

Question

如何使用SQLite批量插入？

我查了一下,似乎我做了一个带有select语句的插入.我用Google搜索,看了一下示例,他们看起来都像是将数据从一个表复制到另一个表,或者与SQLite不兼容.我想做点什么

"INSERT INTO user_msg_media (recipientId, mediaId, catagory, current_media_date) " +
"VALUES(@mediaId, @catagory, @current_media_date)";
where the value of recipientId is the watcher from each of
"SELECT watcher FROM userwatch WHERE watched=@watched";

我尝试了下面的代码,我得到错误"SQLite错误没有这样的列:观察者"

        command.CommandText =
            "CREATE TABLE if not exists user_msg_media( " +
            "msgId        INTEGER PRIMARY KEY, " +
            "recipientId  INTEGER, " +
            "mediaId      INTEGER, " +
            "catagory     INTEGER, " +
            "current_date DATE);";
        command.ExecuteNonQuery();

        //user media
        command.CommandText =
            "CREATE TABLE if not exists user_watch( " +
            "indx INTEGER PRIMARY KEY, " +
            "watcher INTEGER, " +
            "watched INTEGER);";
        command.ExecuteNonQuery();
        //...

    command.CommandText = "SELECT watcher FROM user_watch WHERE watched=:watched;";
    command.Parameters.Add(":watched", DbType.Int64).Value = 1;
    command.ExecuteNonQuery(); //is ok

    command.CommandText =
        "INSERT INTO user_msg_media (recipientId, mediaId, catagory, current_media_date) " +
        "SELECT watcher, :mediaId, :category, :current_media_date" +
        "FROM user_watch WHERE watched=:watched;";
    command.Parameters.Add(":mediaId", DbType.Int64).Value = 0;
    command.Parameters.Add(":category", DbType.Int64).Value = 0;
    command.Parameters.Add(":current_media_date", DbType.Int64).Value = 0;
    command.Parameters.Add(":watched", DbType.Int64).Value = 1;
    command.ExecuteNonQuery();

Answer 1

我编写了一个类来帮助在SQLite中实现批量插入.希望它有用:

http://procbits.com/2009/09/08/sqlite-bulk-insert/

-J.P

Answer 2

SQlite 不支持 @variable 表示法，但是（为了清楚起见，使用 sqlite 的 Python 绑定支持的命名占位符样式）这应该可以工作：

INSERT INTO user_msg_media (userId, mediaId, catagory, current_media_date)
SELECT watcher, :mediaId, :category, :current_media_date
FROM userwatch WHERE watched=:watched

编辑：SQLite 似乎误诊了哪些列名是错误的。列名全部固定后，以下 Python 代码对我有用（不确定您使用的是哪种其他语言，Python 对我来说是与 sqlite 交互的最方便的语言）：

import sqlite3 as sq

con = sq.connect(':memory:')
cur = con.cursor()
cur.execute("CREATE TABLE if not exists user_msg_media( " +
            "msgId        INTEGER PRIMARY KEY, " +
            "recipientId  INTEGER, " +
            "mediaId      INTEGER, " +
            "catagory     INTEGER, " +
            "current_date DATE)")
cur.execute("CREATE TABLE if not exists user_watch( " +
            "indx INTEGER PRIMARY KEY, " +
            "watcher INTEGER, " +
            "watched INTEGER)")

cur.execute("INSERT INTO user_watch VALUES (1, 2, 3)")

cur.execute("SELECT watcher FROM user_watch WHERE watched=:watched",
            dict(watched=3))
print cur.fetchall()

print cur.execute("INSERT INTO user_msg_media (recipientId, mediaId, catagory, current_date) " +
        "SELECT watcher, :mediaId, :category, :current_media_date " +
        "FROM user_watch WHERE watched=:watched;",
        dict(mediaId=0, category=0, current_media_date=0, watched=3)
)

cur.execute("SELECT * FROM user_msg_media")
print cur.fetchall()

但是，如果我在 SQL 中重现不匹配的情况，例如 current_date 与 current_media_date，我可能会错误地诊断缺少的列是watcher，即使该列实际上很好。想要尝试将这个更正后的代码放回到您最喜欢的语言中并看看它的行为如何？