Question

我是高级mysql查询的新手，所以请在这里很好......

假设我有以下表格......

Table Name: users

username   other_non_relevant_field
========   ========================
Bob        blah blah blah
Steve      blah blah blah
Adam       blah blah blah



Table Name: table_1

username    field_abc    field_def    other_non_relevant_field
========    =========    =========    ========================
Steve       quick        brown        blah blah blah
Adam        fox          quick        blah blah blah



Table Name: table_2

username    field_ghi    field_jkl    other_non_relevant_field
========    =========    =========    ========================
Bob         fox          fox          blah blah blah
Bob         brown        quick        blah blah blah
Steve       fox          lazy         blah blah blah
Adam        jump         dog          blah blah blah

因此，假设我想要返回包含单词“quick”或“brown”的所有用户的列表，无论它们在哪个表或字段中，并根据相关性显示结果。为此，我使用此查询：

SELECT users.username, table_1.field_abc, table_1.field_def,
    table_2.field_ghi, table_2.field_jkl
FROM users
JOIN table_1 ON ( table_1.username=users.username )
JOIN table_2 ON ( table_2.username=users.username )
WHERE
    table_1.field_abc LIKE "%quick%" OR table_1.field_abc LIKE "%brown%"
    OR
    table_1.field_def LIKE "%quick%" OR table_1.field_def LIKE "%brown%"
    OR
    table_2.field_ghi LIKE "%quick%" OR table_2.field_ghi LIKE "%brown%"
    OR
    table_2.field_jkl LIKE "%quick%" OR table_2.field_jkl LIKE "%brown%"
ORDER BY (
    (
        CASE WHEN table_1.field_abc LIKE "%quick%"
        THEN 1
        ELSE 0
        END
    ) + (
        CASE WHEN table_1.field_abc LIKE "%brown%"
        THEN 1
        ELSE 0
        END
    ) + (
        CASE WHEN table_1.field_def LIKE "%quick%"
        THEN 1
        ELSE 0
        END
    ) + (
        CASE WHEN table_1.field_def LIKE "%brown%"
        THEN 1
        ELSE 0
        END
    ) + (
        CASE WHEN table_2.field_ghi LIKE "%quick%"
        THEN 1
        ELSE 0
        END
    ) + (
        CASE WHEN table_2.field_ghi LIKE "%brown%"
        THEN 1
        ELSE 0
        END
    ) + (
        CASE WHEN table_2.field_jkl LIKE "%quick%"
        THEN 1
        ELSE 0
        END
    ) + (
        CASE WHEN table_2.field_jkl LIKE "%brown%"
        THEN 1
        ELSE 0
        END
    )
) DESC;

我现在有几个问题......

1）查询似乎很长。有没有更简单的方法呢？

2）如何使LIKE不区分大小写，以便％qUiCk％仍会返回结果？

3）目前每个相关记录都被退回;但是，我实际上只希望每个用户只有一个结果，但首先列出最高相关用户。我该怎么做？

Answer 1

要回答问题1），您可以替换

LIKE '%a%' OR LIKE '%b%'

与

REGEXP '(a|b)'

其次，a REGEXP b如果为true则返回1，如果为false则返回0，因此您可以删除CASE中的ORDER BY。试试这个：

SELECT users.username, table_1.field_abc, table_1.field_def,
    table_2.field_ghi, table_2.field_jkl
FROM users
JOIN table_1 ON table_1.username = users.username
JOIN table_2 ON table_2.username = users.username
WHERE
    table_1.field_abc REGEXP "(quick|brown)" OR
    table_1.field_def REGEXP "(quick|brown)" OR
    table_2.field_ghi REGEXP "(quick|brown)" OR
    table_2.field_jkl REGEXP "(quick|brown)"
ORDER BY (
    (table_1.field_abc REGEXP "(quick|brown)") +
    (table_1.field_def REGEXP "(quick|brown)") +
    (table_2.field_ghi REGEXP "(quick|brown)") +
    (table_2.field_jkl REGEXP "(quick|brown)")
) DESC;

回答问题2）。对于LIKE，REGEXP和=字段，默认情况下，CHAR和VARCHAR甚至TEXT在MySQL中不区分大小写。要执行区分大小写的搜索，您需要：

添加BINARY关键字。例如：REGEXP BINARY '(a|b)'
将字段类型更改为BINARY或VARBINARY或BLOB
将您要搜索的字段的字符排序更改为区分大小写。

要回答问题3），您需要添加GROUP BY子句，例如：

SELECT users.username, SUM(
    (table_1.field_abc REGEXP "(quick|brown)") +
    (table_1.field_def REGEXP "(quick|brown)") +
    (table_2.field_ghi REGEXP "(quick|brown)") +
    (table_2.field_jkl REGEXP "(quick|brown)")
) hits,
    table_1.field_abc, table_1.field_def,
    table_2.field_ghi, table_2.field_jkl
FROM users
JOIN table_1 ON table_1.username = users.username
JOIN table_2 ON table_2.username = users.username
WHERE
    table_1.field_abc REGEXP "(quick|brown)" OR
    table_1.field_def REGEXP "(quick|brown)" OR
    table_2.field_ghi REGEXP "(quick|brown)" OR
    table_2.field_jkl REGEXP "(quick|brown)"
GROUP BY
    users.username
ORDER BY (
    (table_1.field_abc REGEXP "(quick|brown)") +
    (table_1.field_def REGEXP "(quick|brown)") +
    (table_2.field_ghi REGEXP "(quick|brown)") +
    (table_2.field_jkl REGEXP "(quick|brown)")
) DESC;

mySQL查询 - 多个表 - 按相关性排序 - 删除重复项

1 个答案: