找到文本位置，提取文本并在MySQL的新列中插入 [英] Locate text position, extract text and insert in new column in MySQL

问题描述

我在MySQl表中有以下行示例

I have the following example of rows in a MySQl table

              Column A    

Row1    Lauguage=English&Country=USA&Gender=Male
Row2    Gender=Female&Language=French&Country=
Row3    Country=Canada&Gender=&Language=English

如何实现以下目标:例如，我需要查找国家/地区

How can I achieve the following: For example, I need to look for Country

1. 我需要在此文本列中找到国家/地区"的位置.这逐行变化.
2. 然后我需要忽略参数"Country ="，而仅提取值.在某些情况下，这将为NULL(如Row2中的示例)，而在某些行中，我需要后面跟有'='的值(如Row1& Row3中的示例).但是，我需要确保仅获得价值.不是下一个由'&'
分隔的参数
3. 一旦提取了Country参数的值，我需要创建一个新列，现在将在其中提取和存储这些值.

最终结果:新列

              Column B                                                

Row1            USA                            
Row2                              
Row3           Canada                                  

这里的任何帮助将不胜感激！谢谢！

Any help here would be appreciated! Thanks!

推荐答案

您可以选择"Country ="之后的文本，然后在拥有该子字符串之后，选择第一个&"之前的文本

You can pick the text following the 'Country=', and then once you have that substring, pick the text before the first '&'

SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(ColumnA, 'Country=', -1), '&', 1) AS ColumnB
FROM `atable`

请参见 http://dev.mysql.com/doc/refman/5.6/en/string-functions.html#function_substring-index

这是测试以证明:

mysql> SELECT * FROM atable;
+------+------------------------------------------+
| row  | columna                                  |
+------+------------------------------------------+
| Row1 | Lauguage=English&Country=USA&Gender=Male |
| Row2 | Gender=Female&Language=French&Country=   |
| Row3 | Country=Canada&Gender=&Language=English  |
+------+------------------------------------------+

mysql> SELECT SUBSTRING_INDEX(SUBSTRING_INDEX(ColumnA, 'Country=', -1), '&', 1) AS ColumnB FROM atable;
+---------+
| ColumnB |
+---------+
| USA     |
|         |
| Canada  |
+---------+

---

关于您的后续问题:

---

Re your followup question:

INSERT INTO atable VALUES ('Row4', 'Gender=&Language=English');

SELECT `row`, IF(LOCATE('Country=', ColumnA)>0, 
  COALESCE(
    NULLIF(SUBSTRING_INDEX(SUBSTRING_INDEX(ColumnA, 'Country=', -1), '&', 1), ''), 
    'Blank string is not valid!'), 
 'Missing Country!') AS ColumnB     
FROM `atable`

+------+----------------------------+
| row  | ColumnB                    |
+------+----------------------------+
| Row1 | USA                        |
| Row2 | Blank string is not valid! |
| Row3 | Canada                     |
| Row4 | Missing Country!           |
+------+----------------------------+

这篇关于找到文本位置，提取文本并在MySQL的新列中插入的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！