> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/database-devops/3.0/use-db-devops/governance-and-compliance/using-approval-gates-with-harness-ui.md).
# Preview SQL with Manual Approval
Harness DB DevOps allows you to integrate a **Preview SQL** step in your pipeline to review generated SQL before applying schema changes to the database.\
This workflow ensures **governance, visibility, and control**, as you can add a **Manual Approval** step between previewing and executing the changes.
The typical workflow looks like this:
1. Run the **Preview SQL** step to generate SQL for the changes.
2. Pause the pipeline at a **Manual Approval** gate for human verification.
3. After approval, proceed with the **DB Schema Apply** step to deploy the changes.
{% tabs %}
{% tab title="Pipeline Setup" %}
{% endtab %}
{% tab title="YAML Setup" %}
```yaml
pipeline:
name: approval
identifier: muxsql
projectIdentifier: default_project
orgIdentifier: default
tags: {}
stages:
- stage:
name: deploy
identifier: deploy
description: "Pipeline to deploy DB schema changes with approval gates"
type: Custom
spec:
execution:
steps:
- stepGroup:
name: preview
identifier: preview
steps:
- step:
type: DBSchemaUpdateSQL
name: DBSchemaUpdateSQL_1
identifier: DBSchemaUpdateSQL_1
spec:
connectorRef: account.harnessImage
dbSchema: cockroachDB
dbInstance: cab
timeout: 10m
stepGroupInfra:
type: KubernetesDirect
spec:
connectorRef: db
- step:
type: HarnessApproval
name: Approval
identifier: Approval
spec:
approvalMessage: Please review the following information and approve the pipeline progression <+execution.steps.Preview.steps.DBSchemaUpdateSQL_1.output.sqlCommands>
includePipelineExecutionHistory: true
isAutoRejectEnabled: false
approvers:
userGroups:
- account._account_all_users
minimumCount: 1
disallowPipelineExecutor: false
approverInputs: []
timeout: 1d
- stepGroup:
name: deploy
identifier: deploy
steps:
- step:
type: DBSchemaApply
name: DB Schema Apply
identifier: DB_Schema_Apply
spec:
connectorRef: account.harnessImage
dbSchema: cockroachDB
dbInstance: cab
markNextChangeSetRun: true
delegateSelectors:
- harness-gke-delegate
timeout: 10m
stepGroupInfra:
type: KubernetesDirect
spec:
connectorRef: db
rollbackSteps: []
serviceDependencies: []
tags: {}
```
{% endtab %}
{% endtabs %}
### Set up the workflow
In your pipeline’s **Execution** tab, add the following steps:
| Step | Description |
| ------------------- | ---------------------------------------------------------------------------- |
| **Preview SQL** | Generates SQL statements from your changelog or schema definition. |
| **Approval** | Adds a manual approval gate where users must review and confirm SQL changes. |
| **DB Schema Apply** | Applies the approved SQL changes to the target database instance. |
### SQL preview
The **Preview SQL** step shows a generated SQL script based on the detected changes.\
This allows DBAs and developers to:
* Validate the correctness of the SQL.
* Identify potential issues such as destructive changes.
* Ensure compliance with internal policies.
Example output:
```sql
CREATE TABLE products
(
id SERIAL,
name TEXT NOT NULL,
price NUMERIC(10,2) NOT NULL DEFAULT 0.00,
CONSTRAINT products_pkey PRIMARY KEY (id)
);
```
### Reference SQL output in approval messages
To display the generated SQL in your approval message, use the Preview SQL step's output variable:
```sh
<+execution.steps.[StepGroup_ID].steps.[PreviewSQL_Step_ID].output.sqlCommands>
```
For example, if your step group identifier is `Preview_SQL` and the Preview SQL step identifier is `Test_Policies`, use:
```sh
<+execution.steps.Preview_SQL.steps.Test_Policies.output.sqlCommands>
```
### Manual approval step
The Approval step acts as a gate in the pipeline. When the pipeline reaches this stage:
* A notification is sent to the designated approvers.
* Approvers can review the Preview SQL output before continuing.
* The pipeline proceeds to the DB Schema Apply step only after approval. This ensures that no schema changes are deployed without human validation.
### Apply schema changes
After approval, the pipeline executes the `Apply Schema` step. This deploys the reviewed SQL script to the configured database instance. For example:
* **Preview SQL:** shows the generated ALTER TABLE statement.
* **Approval:** DBA confirms the change is safe.
* **DB Schema Apply:** Executes the approved change on the target database.
### Next steps
* Go to [Apply a DB schema step](/database-devops/3.0/use-db-devops/deployment-pipeline-configuration/step-types/apply-dbschema-step.md) to deploy schema changes in your pipeline.
* Go to [Rollback for database schemas](/database-devops/3.0/use-db-devops/deployment-pipeline-configuration/rollback-and-failure-strategies/rollback-for-database-schemas.md) to configure automated rollback for failed deployments.