mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-15 10:52:30 +00:00
98 lines
2.7 KiB
Markdown
98 lines
2.7 KiB
Markdown
---
|
||
slug: /zh/engines/table-engines/integrations/jdbc
|
||
sidebar_position: 34
|
||
sidebar_label: JDBC表引擎
|
||
---
|
||
|
||
# JDBC {#table-engine-jdbc}
|
||
|
||
允许CH通过 [JDBC](https://en.wikipedia.org/wiki/Java_Database_Connectivity) 连接到外部数据库。
|
||
|
||
|
||
要实现JDBC连接，CH需要使用以后台进程运行的程序 [clickhouse-jdbc-bridge](https://github.com/ClickHouse/clickhouse-jdbc-bridge)。
|
||
|
||
该引擎支持 [Nullable](../../../sql-reference/data-types/nullable.md) 数据类型。
|
||
|
||
|
||
## 建表 {#creating-a-table}
|
||
|
||
``` sql
|
||
CREATE TABLE [IF NOT EXISTS] [db.]table_name
|
||
(
|
||
columns list...
|
||
)
|
||
ENGINE = JDBC(datasource_uri, external_database, external_table)
|
||
```
|
||
|
||
**引擎参数**
|
||
|
||
- `datasource_uri` — 外部DBMS的URI或名字.
|
||
|
||
URI格式: `jdbc:<driver_name>://<host_name>:<port>/?user=<username>&password=<password>`.
|
||
MySQL示例: `jdbc:mysql://localhost:3306/?user=root&password=root`.
|
||
|
||
- `external_database` — 外部DBMS的数据库名.
|
||
|
||
- `external_table` — `external_database`中的外部表名或类似`select * from table1 where column1=1`的查询语句.
|
||
|
||
## 用法示例 {#usage-example}
|
||
|
||
通过mysql控制台客户端来创建表
|
||
|
||
Creating a table in MySQL server by connecting directly with it’s console client:
|
||
|
||
``` text
|
||
mysql> CREATE TABLE `test`.`test` (
|
||
-> `int_id` INT NOT NULL AUTO_INCREMENT,
|
||
-> `int_nullable` INT NULL DEFAULT NULL,
|
||
-> `float` FLOAT NOT NULL,
|
||
-> `float_nullable` FLOAT NULL DEFAULT NULL,
|
||
-> PRIMARY KEY (`int_id`));
|
||
Query OK, 0 rows affected (0,09 sec)
|
||
|
||
mysql> insert into test (`int_id`, `float`) VALUES (1,2);
|
||
Query OK, 1 row affected (0,00 sec)
|
||
|
||
mysql> select * from test;
|
||
+------+----------+-----+----------+
|
||
| int_id | int_nullable | float | float_nullable |
|
||
+------+----------+-----+----------+
|
||
| 1 | NULL | 2 | NULL |
|
||
+------+----------+-----+----------+
|
||
1 row in set (0,00 sec)
|
||
```
|
||
|
||
在CH服务端创建表，并从中查询数据：
|
||
|
||
``` sql
|
||
CREATE TABLE jdbc_table
|
||
(
|
||
`int_id` Int32,
|
||
`int_nullable` Nullable(Int32),
|
||
`float` Float32,
|
||
`float_nullable` Nullable(Float32)
|
||
)
|
||
ENGINE JDBC('jdbc:mysql://localhost:3306/?user=root&password=root', 'test', 'test')
|
||
```
|
||
|
||
``` sql
|
||
SELECT *
|
||
FROM jdbc_table
|
||
```
|
||
|
||
``` text
|
||
┌─int_id─┬─int_nullable─┬─float─┬─float_nullable─┐
|
||
│ 1 │ ᴺᵁᴸᴸ │ 2 │ ᴺᵁᴸᴸ │
|
||
└────────┴──────────────┴───────┴────────────────┘
|
||
```
|
||
|
||
``` sql
|
||
INSERT INTO jdbc_table(`int_id`, `float`)
|
||
SELECT toInt32(number), toFloat32(number * 1.0)
|
||
FROM system.numbers
|
||
```
|
||
|
||
## 参见 {#see-also}
|
||
|
||
- [JDBC表函数](../../../sql-reference/table-functions/jdbc.md).
|