Extract a value from a string in a table?

I am trying to extract a value from a string in a table like this below,

我试图从表中的字符串中提取一个值,如下所示,

query table,

query_id    value
1           type={"page":"page"}&parent_id=10&image=on&content=on
2           type={"page":"page"}&parent_id=self
3           type={"category":"contact"}

as you can see the parent_id is in the query and sometimes is not.

正如您所看到的,parent_id在查询中,有时则不是。

I want to extract parent_id so I get this result,

我想提取parent_id所以我得到了这个结果,

query_id    page_id     value
1           10          type={"page":"page"}&parent_id=10&image=on&content=on
2           self        type={"page":"page"}&parent_id=self
3           null        type={"category":"contact"}

I try with this query,

我尝试这个查询,

SELECT 
    *,
    CAST(
        SUBSTRING(
            value,PATINDEX('%parent_id=%', value) + 8,(PATINDEX('%&%', substring(value,PATINDEX('%parent_id=%', value),50)) - 9)
            ) AS INT
        ) AS page_id
FROM query

however I get this error,

但我得到这个错误,

1064 - You have an error in your SQL syntax; check the manual that corresponds
to your MySQL server version for the right syntax to use
near 'INT ) AS page_id FROM query LIMIT 0, 30' at line 6

EDIT:

Maybe I should not be using PATINDEX as I tested it with the query below,

也许我不应该使用PATINDEX,因为我使用下面的查询测试它,

SELECT 
    *,
    SUBSTRING(
            value,PATINDEX('%parent_id=%', value) + 8,(PATINDEX('%&%', substring(value,PATINDEX('%parent_id=%', value),50)) - 9)
            ) AS test
FROM query

I get this error,

我收到这个错误,

#1305 - FUNCTION mydb.PATINDEX does not exist

EDIT:

Got my answer,

得到了我的答案,

SELECT 
    *,
    IF(LOCATE('parent_id=', value)>0,SUBSTRING_INDEX(SUBSTRING(value,LOCATE('parent_id=', value) + 10),'&',1),null)AS page_id
FROM query

1 个解决方案

#1

INT is already used in MYSQL. Use the right syntax

INT已经在MYSQL中使用。使用正确的语法

SELECT 
    *,
    CAST(
        SUBSTRING(
            `value`,PATINDEX('%parent_id=%', `value`) + 8,(PATINDEX('%&%', substring(`value`,PATINDEX('%parent_id=%', `value`),50)) - 9)
            ) AS `INT`
        ) AS `page_id`
FROM `query`