Creating dynamic SQL queries with Snowflake JavaScript procedures

Question

Pulumi · Accepted Answer

To dynamically create SQL queries in Snowflake using JavaScript stored procedures, you can leverage Pulumi's `snowflake.Procedure` resource. Snowflake's JavaScript stored procedures allow you to write procedural logic to execute SQL statements dynamically.

Here, I will show you how to use Pulumi with TypeScript to define a Snowflake stored procedure that executes a dynamic SQL query. The procedure will be written in JavaScript and it will be created in an existing schema and database within your Snowflake account.

Let's break down the steps:

1. Define a new Procedure resource using `snowflake.Procedure`.
2. Provide the necessary properties such as `name`, `schema`, `database`, `arguments`, and `statement`. The `statement` will contain the JavaScript code for the procedure.

For example, the `statement` property could be a Snowflake JavaScript procedure that accepts a table name and a filter condition as arguments and constructs a dynamic SQL query to select data from the given table based on the filter condition.

Below is a program demonstrating how to define such a stored procedure with Pulumi. Note that you should have the Pulumi CLI installed and be authenticated with your Snowflake account as a prerequisite to running this code.

```typescript
import * as pulumi from "@pulumi/pulumi";
import * as snowflake from "@pulumi/snowflake";

// Create a new Snowflake procedure
const dynamicQueryProcedure = new snowflake.Procedure("dynamicQueryProcedure", {
    // Replace with your desired database and schema
    database: "my_database",
    schema: "my_schema",
    // Procedure name
    name: "fetch_dynamic_data",
    // Procedure arguments
    arguments: [
        { name: "tableName", type: "VARCHAR" },
        { name: "condition", type: "VARCHAR" }
    ],
    // The JavaScript code for the procedure
    statement: `
        CREATE OR REPLACE PROCEDURE fetch_dynamic_data(TABLENAME VARCHAR, CONDITION VARCHAR)
        RETURNS VARIANT
        LANGUAGE JAVASCRIPT
        AS
        $$
        var query = 'SELECT * FROM ' + TABLENAME + ' WHERE ' + CONDITION;
        var statement1 = snowflake.createStatement({sqlText: query});
        var result_set = statement1.execute();
        var resultSet = [];
        while(result_set.next()) {
            resultSet.push(result_set.getColumnValue(1));
        }
        return resultSet;
        $$
        ;
    `,
    // Procedure return type
    returnType: "VARIANT"
});

// Export the name of the procedure
export const procedureName = dynamicQueryProcedure.name;
```

This code snippet defines a stored procedure named `fetch_dynamic_data` that can be used to execute a query constructed from its arguments. The `arguments` array specifies that this procedure takes two arguments: a table name and a condition string.

The `statement` includes JavaScript for the stored procedure. It shows how you can build a dynamic SQL statement using input arguments in JavaScript within a Snowflake procedure. In this case, the procedure constructs a SQL query and executes it, returning the results as an array.

Once this Pulumi program is deployed, the `fetch_dynamic_data` stored procedure will be available in Snowflake, and you can call it to dynamically generate and execute SQL queries. Ensure you handle SQL injection risks when using dynamic SQL queries by implementing appropriate security measures within your procedure logic.

To run the Pulumi program, you would execute `pulumi up` in your terminal within the project directory. This command will create or update cloud resources based on the code you've written.