Cara menggunakan json functions in mysql

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SELECT LastName FROM Employees

The query above selects all the data in the "LastName" column from the "Employees" table.

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MySQL 5.7.8+ supports native JSON type. While you have different ways to create json objects, you can access and read members in different ways, too.

Table of Contents

• # Read JSON Array value
• How extract JSON data from column in MySQL?
• What is JSON extract () function in MySQL?
• Can MySQL parse JSON?
• How do I iterate through a JSON array in MySQL?

Main function is JSON_EXTRACT, hence -> and ->> operators are more friendly.

# Read JSON Array value

Create @myjson variable as JSON type (read more (opens new window)):

SELECT some members!

Extract path by -> or ->> Operators, while ->> is UNQUOTED value:

So col->>path is equal to JSON_UNQUOTE(JSON_EXTRACT(col,path)) :

As with ->, the ->> operator is always expanded in the output of EXPLAIN, as the following example demonstrates:

Read about inline path extract(+) (opens new window)

# Syntax

• JSON_EXTRACT(json_doc,path[,...])
• JSON_EXTRACT(json_doc,path)
• JSON_EXTRACT(json_doc,path2,path2)

# Parameters

Mentioned in MySQL 5.7 Reference Manual (opens new window)

• Multiple matched values by path argument(s)

If it is possible that those arguments could return multiple values, the matched values are autowrapped as an array, in the order corresponding to the paths that produced them. Otherwise, the return value is the single matched value.

My json is of the format ["a","b","c"]. I want to write a sql query such that

select *
from mytable
where a_column in json_extract["a","b","c"]

This logic does not work, because json_extract needs a path.

Is there any work around for this in mysql 8.0

asked May 17 at 5:34

SELECT *
FROM mytable
WHERE JSON_CONTAINS('["a","b","c"]', JSON_QUOTE(a_column));

I assume that the column a_column is a string-type column which contains a value like 'a'.

answered May 17 at 12:50

AkinaAkina

17.5k2 gold badges11 silver badges19 bronze badges

I have a problem extracting data in the JSON column. I'm new to this JSON method, unlike relation tables.

Sample Table: every minute/second all websites activity will be saved in 1 column alongside timestamp.

Expected Table: I wanted to produce is to extract the object details of a specific id, so I can have a full table of that objects.

SELECT dtime, activity.id, activity.ssl, activity.online, activity.cert
FROM logs
WHERE activity.id = 3 

dbfiddle:

https://dbfiddle.uk/?rdbms=mariadb_10.4&fiddle=7982cd1738b4fc594fb033403a492a6c

asked Feb 2 at 19:01

スペースタイムスペースタイム

411 silver badge6 bronze badges

1

Finally, I found the problem.

1. Make sure you check the version if JSON functions are supported.

• MySQL8+
• MariaDB 10.6.0+

In my case, this was easily fixed by JSON_TABLE just like this post "read json array on mysql query"

SELECT 
  dtime, 
  get_activity.* 
FROM 
  logs, 
  JSON_TABLE(
    activity, 
    '$[*]' COLUMNS (
      `id` int(11) PATH '$.ID', 
      `ssl` int(1) PATH '$.SSL', 
      `online` int(1) PATH '$.Online', 
      `cert` text PATH '$.Cert'
    )
  ) get_activity 
WHERE 
  get_activity.id = 3;

All Result:

Result using WHERE filter:

dbfiddle

answered Feb 3 at 18:10

スペースタイムスペースタイム

411 silver badge6 bronze badges

How extract JSON data from column in MySQL?

Key takeaway for extracting data from a JSON field in MySQL:.

Use $. ... .

Use $[index] to extract the value of an element from a JSON array..

Use -> as a shortcut for JSON_EXTRACT if the value is not a string..

What is JSON extract () function in MySQL?

In MySQL, the JSON_EXTRACT() function returns data from a JSON document. The actual data returned is determined by the path you provide as an argument. You provide the JSON document as the first argument, followed by the path of the data to return.

Can MySQL parse JSON?

In MySQL, JSON values are written as strings. MySQL parses any string used in a context that requires a JSON value, and produces an error if it is not valid as JSON.

How do I iterate through a JSON array in MySQL?

SET products = (SELECT JSON_EXTRACT(dataObject, "$. products")); SET productId = (SELECT JSON_EXTRACT(products, "$[0]. productId")); I get the inner products json and the id of the 0th product.