# CREATE VIEW

> StackQL 中的 CREATE VIEW：将查询（包括跨云 UNION）保存为命名视图，或保存为存储结果以供复用的物化视图。

Source: https://stackql.io/zh-hans/language-spec/createview

在会话中创建 `view` 或 `materialized view`，可用于表示较长或复杂的 `stackql` 查询。  

另请参阅：  
[[ `SELECT` ]](/language-spec/select) [[ `REFRESH` ]](/language-spec/refreshview) [[ `DROP` ]](/language-spec/dropview)

* * * 

## 语法

*createViewStatement::=*

   
   

```sql
CREATE [ OR REPLACE ] [ MATERIALIZED ] VIEW <viewName> AS 
<selectStatement> [ UNION | JOIN <selectStatement> ];
```

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## 示例

### `aws` 与 `google` 之间的跨云 `UNION`
```sql
CREATE VIEW dual_cloud_block_storage AS
SELECT 
 'google' AS vendor, 
 name, 
 split_part(split_part(type, '/', 11), '-', 2) AS type, 
 status, 
 sizeGb AS size 
FROM google.compute.disks 
 WHERE project = '<YOUR_GCP_PROJECT>' 
 AND zone = 'australia-southeast1-a'
UNION
SELECT 
 'aws' AS vendor, 
 volumeId AS name, 
 volumeType AS type, 
 status, 
 size 
FROM aws.ec2.volumes 
 WHERE region = 'ap-southeast-2';
```

### 创建并使用物化视图
```sql
/* -------------------------- */
/* create a materialized view */
/* -------------------------- */
CREATE MATERIALIZED VIEW vw_ec2_instance_types AS 
SELECT 
 memoryInfo, 
 hypervisor, 
 autoRecoverySupported, 
 instanceType, 
 SPLIT_PART(processorInfo, '\n', 3) as processorArch, 
 currentGeneration, 
 freeTierEligible, 
 hibernationSupported,
 SPLIT_PART(vCpuInfo, '\n', 2) as vCPUs, 
 bareMetal, 
 burstablePerformanceSupported, 
 dedicatedHostsSupported 
FROM aws.ec2.instance_types 
WHERE region = 'us-east-1';
/* ------------------------- */
/* use the materialized view */
/* ------------------------- */
SELECT 
 i.instanceId, 
 i.instanceType, 
 it.vCPUs, 
 it.memoryInfo 
FROM aws.ec2.instances i 
 INNER JOIN vw_ec2_instance_types it 
 ON i.instanceType = it.instanceType 
WHERE i.region = 'us-east-1';
```