How to Handle \'Database does not exist\' Errors with pq.Error in Postgres?

Error Codes in Postgres After db.Exec()

When executing a query using db.Exec(), the returned error can provide valuable information about the status of the operation. While the actual error message may vary, the Postgres driver provides a way to inspect error codes for specific conditions.

Accessing Error Codes

To access the error code from the error returned by db.Exec(), you can type assert it to the *pq.Error type and then use its Code field. Here's an example:

<code class="go">if err, ok := err.(*pq.Error); ok {
    fmt.Println("Error code:", err.Code)
}</code>

Error Code for "Database does not exist"

Unfortunately, Postgres does not provide a specific error code for "database does not exist" errors. The Code field of the error will likely be set to "42P01" (for "syntax error"), but this is not guaranteed.

Checking for Specific Error Codes

Since there is no specific error code for "database does not exist" errors, you will need to manually parse the error message string yourself. You can use the strings package to do this effectively:

<code class="go">if strings.Contains(err.Error(), "existence") && strings.Contains(err.Error(), "database") {
    // Database does not exist
}</code>

Additional Error Fields

In addition to the error code, the pq.Error type provides other fields that can provide valuable context, such as:

• Message: The error message string
• Detail: Detailed information about the error
• Hint: A hint on how to resolve the error
• Position: The position in the input query where the error occurred
• Where: The source of the error within the query

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