MariaDB 10.0.X中，动态列（Dynamic Columns），可以支持 JSON 格式来获取数据。
为了兼容传统SQL语法，MariaDB 10和MySQL5.7支持原生JSON格式，即关系型数据库和文档型NoSQL数据库集于一身。
使用说明：
###表结构
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create table assets (
item_name varchar(32) primary key, -- A common attribute
for
all items
dynamic_cols blob -- Dynamic columns will be stored here
);
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###插入JSON格式数据
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mysql> INSERT INTO assets VALUES
-> (
'MariaDB T-shirt'
, COLUMN_CREATE(
'color'
,
'blue'
,
'size'
,
'XL'
));
Query OK, 1 row affected (0.02 sec)
mysql> INSERT INTO assets VALUES
-> (
'Thinkpad Laptop'
, COLUMN_CREATE(
'color'
,
'black'
,
'price'
, 500));
Query OK, 1 row affected (0.01 sec)
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###获取Key（键）color的Value（值）：
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mysql> SELECT item_name, COLUMN_GET(dynamic_cols,
'color'
as char) AS color FROM assets;
+-----------------+-------+
| item_name | color |
+-----------------+-------+
| MariaDB T-shirt | blue |
| Thinkpad Laptop | black |
+-----------------+-------+
2 rows
in
set
(0.00 sec)
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###获取全部Key（键）
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mysql> SELECT item_name, column_list(dynamic_cols) FROM assets;
+-----------------+---------------------------+
| item_name | column_list(dynamic_cols) |
+-----------------+---------------------------+
| MariaDB T-shirt | `size`,`color` |
| Thinkpad Laptop | `color`,`price` |
+-----------------+---------------------------+
2 rows
in
set
(0.00 sec)
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###获取全部Key-Value
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mysql> SELECT item_name, COLUMN_JSON(dynamic_cols) FROM assets;
+-----------------+-------------------------------+
| item_name | COLUMN_JSON(dynamic_cols) |
+-----------------+-------------------------------+
| MariaDB T-shirt | {
"size"
:
"XL"
,
"color"
:
"blue"
} |
| Thinkpad Laptop | {
"color"
:
"black"
,
"price"
:500} |
+-----------------+-------------------------------+
2 rows
in
set
(0.01 sec)
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###删除一个Key-Value：
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mysql> UPDATE assets SET dynamic_cols=COLUMN_DELETE(dynamic_cols,
"price"
)
-> WHERE COLUMN_GET(dynamic_cols,
'color'
as char)=
'black'
;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT item_name, COLUMN_JSON(dynamic_cols) FROM assets;
+-----------------+------------------------------+
| item_name | COLUMN_JSON(dynamic_cols) |
+-----------------+------------------------------+
| MariaDB T-shirt | {
"size"
:
"XL"
,
"color"
:
"blue"
} |
| Thinkpad Laptop | {
"color"
:
"black"
} |
+-----------------+------------------------------+
2 rows
in
set
(0.00 sec)
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###增加一个Key-Value：
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mysql> UPDATE assets SET dynamic_cols=COLUMN_ADD(dynamic_cols,
'warranty'
,
'3 years'
)
-> WHERE item_name=
'Thinkpad Laptop'
;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT item_name, COLUMN_JSON(dynamic_cols) FROM assets;
+-----------------+----------------------------------------+
| item_name | COLUMN_JSON(dynamic_cols) |
+-----------------+----------------------------------------+
| MariaDB T-shirt | {
"size"
:
"XL"
,
"color"
:
"blue"
} |
| Thinkpad Laptop | {
"color"
:
"black"
,
"warranty"
:
"3 years"
} |
+-----------------+----------------------------------------+
2 rows
in
set
(0.00 sec)
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###更改一个Key-Value：
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mysql> UPDATE assets SET
dynamic_cols=COLUMN_ADD(dynamic_cols,
'color'
,
'white'
) WHERE
COLUMN_GET(dynamic_cols,
'color'
as char)=
'black'
;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> SELECT item_name, COLUMN_JSON(dynamic_cols) FROM assets;
+-----------------+----------------------------------------+
| item_name | COLUMN_JSON(dynamic_cols) |
+-----------------+----------------------------------------+
| MariaDB T-shirt | {
"size"
:
"XL"
,
"color"
:
"blue"
} |
| Thinkpad Laptop | {
"color"
:
"white"
,
"warranty"
:
"3 years"
} |
+-----------------+----------------------------------------+
2 rows
in
set
(0.00 sec)
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