Question

我有一个MySQL列，其中有一组用空格分隔的数字。大约有330个空间.....并且它们并非都在同一个地方（每一组）有没有办法可以自动执行此操作，例如通过查询？或者这可能在Microsoft SQL中吗？

编辑1：我担心我没有真正尝试过任何事情， - 不确定该怎么做。以下是其中一组数字的示例

3 10 13 18 0 0 175 215 177 173 213 203 592 272 0 175 215 177 173 215 177 172 208 203 592

这是非常重复的。

Answer 1

您可以生成一个数字列表，然后使用SUBSTRING_INDEX对数据进行交叉连接以获取各个字段。

这样的事情： -

SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(SomeField, ' ', aNum + 1), ' ', -1)
FROM SomeTable
CROSS JOIN
(
    SELECT Units.aCnt + Tens.aCnt * 10 + Hundreds.aCnt * 100 AS aNum
    FROM
    (SELECT 0 AS aCnt UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) Units,
    (SELECT 0 AS aCnt UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) Tens,
    (SELECT 0 AS aCnt UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) Hundreds
) Sub1
WHERE LENGTH(SomeField) - LENGTH(REPLACE(SomeField, ' ', '')) >= aNum

SQL小提琴： -

http://www.sqlfiddle.com/#!2/7c43a/4

然后找到设计数据库表的人并向他们解释数据库设计/规范化/索引。

编辑 - 一种可以（几乎）做这个选择的方法，应对cols的数量。对于该行不存在的任何col，它应该返回NULL。可能最适合在MySQL存储过程中使用。它计算最大cols数，然后生成一些动态SQL来获取cols。

SET @sql = NULL;

SET SESSION group_concat_max_len = 1000000;

SELECT GROUP_CONCAT(aField ORDER BY aNum)
INTO @sql
FROM
(
    SELECT (Units.aCnt + Tens.aCnt * 10 + Hundreds.aCnt * 100) AS aNum, CONCAT("IF(LENGTH(SomeField) - LENGTH(REPLACE(SomeField, ' ', '')) >= ", (Units.aCnt + Tens.aCnt * 10 + Hundreds.aCnt * 100), ", SUBSTRING_INDEX(SUBSTRING_INDEX(SomeField, ' ', ", (Units.aCnt + Tens.aCnt * 10 + Hundreds.aCnt * 100 + 1),"), ' ', -1), NULL) AS col",(Units.aCnt + Tens.aCnt * 10 + Hundreds.aCnt * 100)) AS aField
    FROM (SELECT MAX(LENGTH(SomeField) - LENGTH(REPLACE(SomeField, ' ', ''))) AS MaxDelim FROM SomeTable) Sub1,
    (SELECT 0 AS aCnt UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) Units,
    (SELECT 0 AS aCnt UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) Tens,
    (SELECT 0 AS aCnt UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) Hundreds
    WHERE Units.aCnt + Tens.aCnt * 10 + Hundreds.aCnt * 100 <= Sub1.MaxDelim
) Sub2;

SET @sql = CONCAT('SELECT ', @sql,
                  '  FROM SomeTable
                    ');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

SQL小提琴： -

http://www.sqlfiddle.com/#!2/a28ab2/2

将mySQL列拆分为多个

1 个答案: