MySQL（如果存在）（选择），更新，否则，使用日期比较以python插入

Question

我正在尝试执行db更新，条件是在满足其各自条件的情况下，对于多列具有DATE值的数据库记录存在，但我似乎遇到了麻烦。 任何帮助深表感谢。 谢谢！

以下代码

    select_cmd = "SELECT * FROM " + self.designator + " WHERE player_fkid=" + str(fixed['player_fkid']) + \
                    " AND team_fkid=" + str(fixed['team_fkid']) + " AND season_fkid=" + str(fixed['season_fkid'])

    update_start_cmd = "UPDATE " + self.designator + " SET date_start='" + str(update['date_start']) + \
                    "' WHERE date_start>'" + str(update['date_start']) + "'"

    update_end_cmd = "UPDATE " + self.designator + " SET date_end='" + str(update['date_end']) + "' WHERE date_end<'" + \
                    str(update['date_end']) + "'"

    insert_cmd = "INSERT INTO " + self.designator + " (player_fkid, team_fkid, season_fkid, date_start, date_end) VALUES (" + \
                    str(fixed['player_fkid']) + ", " + str(fixed['team_fkid']) + ", " + str(fixed['season_fkid']) + ", '" + \
                    str(update['date_start']) + "', '" + str(update['date_end']) + "')"

    cmd = "IF EXISTS (" + select_cmd + ")" + "\n" + update_start_cmd + "\n" + update_end_cmd + "\nELSE " + insert_cmd

    try:
        cursor.execute(cmd)
        cnx.commit()
    except mysql.connector.errors.ProgrammingError:
        print "Error: invalid command '" + cmd + "'"

返回以下错误：

错误：无效命令'IF EXISTS（SELECT * FROM成员WHERE player_fkid = 1 AND team_fkid = 1 AND season_fkid = 1）
UPDATE名册SET date_start ='2010-04-13'WHERE date_start>'2010-04-13'
UPDATE名册SET date_end ='2010-04-13'WHERE date_end <'2010-04-13'
ELSE INSERT INTO名册（player_fkid，team_fkid，season_fkid，date_start，date_end）值（1、1、1，'2010-04-13'，'2010-04-13'）'

Answer 1

我认为您想在重复键更新语法上使用Insert...。
（特别是有条件的重复密钥更新 ）

就像是：

INSERT INTO roster (player_fkid, team_fkid, season_fkid, date_start, date_end) 
VALUES (1, 1, 1, '2010-04-13', '2010-04-13')
ON DUPLICATE KEY UPDATE
date_start= IF(date_start > '2010-04-13', '2010-04-13', values(date_start)),
date_end= IF(date_end > '2010-04-13', '2010-04-13', values(date_end));

Answer 2

我发现以下作品：

    cmd = "SELECT COUNT(1) FROM roster WHERE player_fkid=" + str(fixed['player_fkid']) + " AND team_fkid=" + str(fixed['team_fkid']) + " AND season_fkid=" + str(fixed['season_fkid'])
    cursor.execute(cmd)
    if cursor.fetchone()[0]:
        udpate_sub_cmd = "UPDATE roster"
        date_start_sub_cmd = "SET date_start= IF(date_start > '" + str(update['date_start']) + "', '" + str(update['date_start']) + "', values(date_start)),"
        date_end_sub_cmd = "date_end= IF(date_end > '" + str(update['date_end']) + "', '" + str(update['date_end']) + "', values(date_end));"
        where_sub_cmd = "WHERE player_fkid=" + str(fixed['player_fkid']) + " AND team_fkid=" + str(fixed['team_fkid']) + " AND season_fkid=" + str(fixed['season_fkid'])
        cmd = udpate_sub_cmd + " " + date_start_sub_cmd + " " + date_end_sub_cmd + " " + where_sub_cmd
        cursor.execute(cmd, multi=True)
    else:
        insert_sub_cmd = "INSERT INTO roster (player_fkid, team_fkid, season_fkid, date_start, date_end)" 
        values_sub_cmd = "VALUES (" + str(fixed['player_fkid']) + ", " + str(fixed['team_fkid']) + ", " + str(fixed['season_fkid']) + ", '" + str(update['date_start']) + "', '" + str(update['date_end']) + "')"
        cmd = insert_sub_cmd + " " + values_sub_cmd
        cursor.execute(cmd)

使用前面提到的链接中的部分解决方案。