基于错误进行排序的SQLite查询

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英文:

SQLite query for ordering a list based on mistakes made

问题

以下是翻译好的内容:

我想知道如何根据服务员所犯错误的数量查询数据库。

我有两个表格:

员工表

    String employeeTable = "CREATE TABLE " + EMP_TABLE + " ("
            + ID_EMP + " INTEGER PRIMARY KEY, "
            + FIRST_NAME + " TEXT,"
            + LAST_NAME + " TEXT,"
            + PROFIT + " INTEGER);";

错误员工表

    String mistakeTable = "CREATE TABLE " + MISTAKE_TABLE + " ("
            + ID_MISTAKE + " INTEGER PRIMARY KEY AUTOINCREMENT,"
            + ID_WAITER_MISTAKE + " INTEGER,"
            + ID_ORDER_MISTAKE + " INTEGER,"
            + MISTAKE_TOTAL + " INTEGER,"
            + " FOREIGN KEY (" + ID_WAITER_MISTAKE + ") REFERENCES " + EMP_TABLE + "(" + ID_EMP + "), "
            + " FOREIGN KEY (" + ID_ORDER_MISTAKE + ") REFERENCES " + ORDER_TABLE + "(" + ID_ORDER + "));";

我正试图根据在错误表中使用ID_WAITER_MISTAKE统计的员工错误数量对列表进行排序。

String query = SELECT * , COUNT(Mistake_TABLE.ID_Waiter) as Count
FROM EMP_TABLE
ORDER BY Count DESC
英文:

I would like to know how to query a database based on the amount of mistakes made by a waiter.

The two tables I have are

Employee

    String employeeTable = "CREATE TABLE " + EMP_TABLE + " ("
            + ID_EMP + " INTEGER PRIMARY KEY, "
            + FIRST_NAME + " TEXT,"
            + LAST_NAME + " TEXT,"
            + PROFIT + " INTEGER);";

MistakeEmployee

    String mistakeTable = "CREATE TABLE " + MISTAKE_TABLE + " ("
            + ID_MISTAKE + " INTEGER PRIMARY KEY AUTOINCREMENT,"
            + ID_WAITER_MISTAKE + " INTEGER,"
            + ID_ORDER_MISTAKE + " INTEGER,"
            + MISTAKE_TOTAL + " INITGER,"
            + " FOREIGN KEY (" + ID_WAITER_MISTAKE + ") REFERENCES " + EMP_TABLE + "(" + ID_EMP + "), "
            + " FOREIGN KEY (" + ID_ORDER_MISTAKE + ") REFERENCES " + ORDER_TABLE + "(" + ID_ORDER + "));";

I am trying to order the list based on the Employee with the most Mistakes which would be counted in the mistakes table using the ID_WAITER_MISTAKE.

String query = SELECT * , COUNT(Mistake_TABLE.ID_Waiter) as Count
FROM EMP_TABLE
ORDER BY Count DESC

答案1

得分: 1

String query =
    "SELECT e." + ID_EMP + ", e." + FIRST_NAME + ", e." + LAST_NAME + ", " +
    "COUNT(m." + ID_MISTAKE + ") AS Mistake_Count " +
    "FROM " + EMP_TABLE + " AS e LEFT JOIN " + MISTAKE_TABLE + " AS m " +
    "ON m." + ID_WAITER_MISTAKE + " = e." + ID_EMP + " " +
    "GROUP BY e." + ID_EMP + ", e." + FIRST_NAME + ", e." + LAST_NAME + " " +
    "ORDER BY Mistake_Count DESC, e." + ID_EMP ;
英文:

You must join the tables, group by employee and aggregate:

SELECT e.ID_EMP, e.FIRST_NAME, e.LAST_NAME,
       COUNT(m.ID_MISTAKE) AS Mistake_Count
FROM employeeTable e LEFT JOIN mistakeTable m
ON m.ID_WAITER_MISTAKE = e.ID_EMP
GROUP BY e.ID_EMP, e.FIRST_NAME, e.LAST_NAME
ORDER BY Mistake_Count DESC, e.ID_EMP

and in Java code you should construct the sql string like this:

String query = 
    "SELECT e." + ID_EMP + ", e." + FIRST_NAME + ", e." + LAST_NAME + ", " + 
    "COUNT(m." + ID_MISTAKE + ") AS Mistake_Count " +
    "FROM " + EMP_TABLE + "AS e LEFT JOIN " + MISTAKE_TABLE + " AS m " +
    "ON m." + m.ID_WAITER_MISTAKE + " = e." + ID_EMP + " " +
    "GROUP BY e." + ID_EMP + ", e." + FIRST_NAME + ", e." + LAST_NAME + " " +
    "ORDER BY Mistake_Count DESC, e." + ID_EMP ;

I hope there are no typos.

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  • 本文由 发表于 2020年10月5日 00:05:59
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