如何从字段mysql的前20个字符之后选择字符 [英] how to select characters after first 20 characters from field mysql

问题描述

 select address (first 20 character) as Address1 , 
        address (characters after first 20 if less then 20 then NULL) as Address2
 from customer

如何选择20个字符后的字符串?

How do I select string after 20 characters?

推荐答案

要获取前20个字符之后的字符(请注意，如果不存在20个字符，该函数将返回一个空字符串):

To get characters after the first 20 characters (note that if there are not twenty characters, the function will return an empty string):

SELECT SUBSTRING('Some Random Address That is Longer than 20 characters' FROM 20);

现在，如果您需要地址2为NULL，则首先检查字符长度:

Now if you need address 2 to be NULL, you check character length first:

SELECT if(char_length(address) > 20, SUBSTRING(address FROM 20), NULL);

要获取前20个字符，可以使用以下子字符串函数:

To get the first 20 characters, you can use the substring function like this:

SELECT SUBSTRING('Some Random Address', 1, 20);

现在，最终查询可能如下所示:

Now the final query could look like this:

SELECT SUBSTRING(address, 1, 20) as Address1, 
    IF(CHAR_LENGTH(address) > 20, SUBSTRING(address FROM 20), NULL) as Address2
FROM customer

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